Browse Topic: Water

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Numerical Optimization of a SCR System Based on the Injection of Pure Gaseous Ammonia for the NOx Reduction in Light-Duty Diesel Engines2020-01-03564/14/2020
Selective Catalytic Reduction (SCR) systems are nowadays widely applied for the reduction of NOx emitted from Diesel engines. The typical process is based on the injection of aqueous urea in the exhaust gases before the SCR catalyst, which determines the production of the ammonia needed for the catalytic reduction of NOx. However, this technology is affected by two main limitations: a) the evaporation of the urea water solution (UWS) requires a sufficiently high temperature of the exhaust gases and b) the formation of solid deposits during the UWS evaporation is a frequent phenomenon which compromise the correct operation of the system. In this context, to overcome these issues, a technology based on the injection of gaseous ammonia has been recently proposed: in this case, ammonia is stored at the solid state in a cartridge containing a Strontium Chloride salt and it is desorbed by means of electrical heating. In this work, an after-treatment system based on the injection of gaseous ammonia in the SCR system is considered. Numerical 1D and 3D CFD simulations are applied in order to optimize the NOx reduction process. In particular, CFD methodology is applied to study in details the process of injection of the gaseous ammonia in the main exhaust gas stream and the effectiveness of the mixing process. Different geometrical layouts are compared to evaluate their performances in terms of uniformity of the NH3 distribution across the inlet section of the catalyst and pressure drop introduced in the exhaust line. Moreover, a 1D simulation tool is applied to evaluate the performances of the entire exhaust after-treatment system. The 1D model is calibrated on the basis of the information coming from detailed CFD simulations, in particular for what concerns the modeling of the effects of the different mixer geometries in terms on NH3 distribution. In this case, a simplified 3D catalyst is simulated, to take into account the maldistribution of ammonia at the inlet cross section and to evaluate its impact on the global deNOx performance of the system for different dosing strategies and for different levels of the ammonia maldistribution.
Della Torre, Augusto, Montenegro, Gianluca, Onorati, Angelo, Cerri, Tarcisio, Tronconi, Enrico, Nova, Isabella
Liquid Flow Influenced by a Quantum Effect in WaterTBMG-360282/1/2020
Water is the basis of all life on earth. Its structure is simple — two hydrogen atoms bound to one oxygen atom — yet its behavior is unique among liquids, and scientists still do not fully understand the origins of its distinctive properties.
Ultra-Thin Layers of Rust Generate Electricity from Flowing WaterTBMG-3572212/1/2019
Research shows that thin films of rust (iron oxide) can generate electricity when saltwater flows over them. These films represent an entirely new way of generating electricity and could be used to develop new forms of sustainable power production.
Battery-Free Sensor for Underwater UseTBMG-3544311/1/2019
To investigate oceans, researchers aim to build a submerged network of interconnected sensors that sends data to the surface. Supplying constant power to scores of sensors designed to stay for long durations underwater has been a major problem.
Analysis of a Coupling System of Aircraft Environmental Control and Fuel Tank Inerting Based on Membrane Separation2019-01-18959/16/2019
This paper raises a coupling system of aircraft environmental control and fuel tank inerting based on membrane separation. The system applies a membrane dehumidifier to replace water vapor removal unit of heat regenerator, condenser and water separator, which is widely used in conventional aircraft environmental control system (ECS) nowadays. Water vapor can travel across the membrane wall under its pressure difference without phase change, so the dehumidification process consumes no cooling capacity as traditional ECS and the cooling capacity of the new system increases. This paper first compares the thermodynamic properties of ECS based on membrane dehumidification and the traditional ECS based on condensation. The results show that the membrane dehumidification system has larger cooling capacity and lighter weight. For a given cooling capacity requirement, the membrane dehumidification system can use less bleed air since the enthalpy of the outlet air is lower. Besides, the fuel tank inerting system also uses an air separation module to produce nitrogen enriched air based on membrane separation. After the air is dehumidified in membrane dehumidification ECS, its parameters meet the requirement of membrane air separation module. Thus, it is reasonable to combine the two systems together. This paper conducts a simulation analysis of the coupling system. Comparing with the conventional four wheel high pressure de-water ECS and fuel tank inerting system used onboard nowadays, the coupling system has simpler structure and lighter weight. The simulation results show that the coupling system can decrease the fuel penalty by 139.67kg each pack.
Yuan, Weixing, Zheng, Yan, Hou, Jiaqi
Test Method for Measuring Wet Color Transfer CharacteristicsJ1326_201906 (Historical)6/25/2019
This procedure describes a method of measuring the resistance to wet color transfer of materials such as textiles, leather, and composites.
Textile and Flexible Plastics Committee
Experimental Investigation of the Droplet Field of a Rotating Vehicle Tyre2019-01-50686/18/2019
The consideration of vehicle soiling in the development process becomes ever more important because of the increasing customer demands on current vehicles and the increased use of camera and sensor systems due to autonomous driving. In the process of self-soiling, a soil-water mixture is whirled up by the rotation of the car’s own wheels and deposits on the vehicle surface. The validation of the soiling characteristics in vehicle development usually takes place in an experimental manner, but is increasingly supported by numerical simulations. The droplet field at the tyre has been investigated several times in the past. However, there are no published information regarding the physical background of the droplet formation process and the absolute droplet sizes considering the position at the tyre and the behaviour at different velocities. In the numerical self-soiling simulations, this droplet whirl up process is modelled by a non-rotating wheel, where equally sized droplets are injected tangentially from homogenous emitter lines on the tyre surface into the airfield. The impact of the simplifications of this approach on the final result of a self-soiling simulation has not yet been investigated. To achieve a more realistic droplet field, a new approach for the direct simulation of the droplet whirl up process is proposed by the authors in a previous publication. In order to have a validation basis for the new simulation method and to get a deeper understanding of the droplet formation process, experiments with a detailed analysis of the droplet field have been performed. This study presents the results of experimental investigations of the resulting droplet field for a single rotating tyre in a wind tunnel. The droplet field is exposed by a laser plane and is evaluated with respect to the droplet size and droplet velocity for two different tread designs and tyre speeds.
Strohbücker, Veith, Niesner, Reinhold, Schramm, Domenik, Kuthada, Timo, Joos, Franz
An Experimental Study to Evaluate the Droplet Impinging Erosion Characteristics of an Icephobic, Elastic Soft Surface2019-01-19976/10/2019
Elastic soft material/surface, such as Polydimethylsiloxane (PDMS), is a perspective, useful and low-cost hydrophobic and icephobic coating. While it has been reported to have good mechanical durability, its erosion durability under the high impacting of water droplets pertinent to aircraft inflight icing phenomena has not been explored. In this study, the droplet imping erosion characteristics of an icephobic PDMS surface/material is evaluated systematically upon the dynamic impinging of water droplets at different impact velocities (~ up to 75m/s), in comparison with other state-of-the-art icephobic materials/surfaces, such as superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS). Surprisingly, the contact angle (CA) of the elastic PDMS is shown to have an over 20° increase (from 105° to 128°), which represents better hydrophobicity, after the erosion test which is mainly contributed to the higher roughness of the eroded PDMS surface. As for the icephobicity evaluation, intact PDMS was found to has ultra-low ice adhesion (~8 kPa), in comparison with SHS (i.e., ~100kPa) and SLIPS (i.e., ~35kPa). PDMS also shows outstandingly stable ice adhesion during the erosion test (i.e., fluctuation only within ~4kPa) as a result of the growth of cracks on the PDMS surface and the increased surface energy.
Ma, Liqun, Zhang, Zichen, Liu, Yang, Hu, Hui
Type IV Anti-Icing Fluid Subjected to Light Freezing Rain: Visual and Thermal Analysis2019-01-19716/10/2019
Deicing the aircraft using fluid, prior takeoff is mandatory; since a thin layer of ice or snow can compromise the safety. With the same idea, to use anti-icing fluid during a frozen precipitation to protect the aircraft is also essential. Commercialized anti-icing fluids all pass the process of qualification as described in the SAE documents. One of these documents specifies a set of tests that reproduce freezing precipitation to obtain endurance time and then the holdover timetables. The endurance time is determined by visual inspection: when 30% of the plate is covered with frozen contaminants. With the evolution of technology and the venue of new tools, it may simplify the process, and at least confirm the observations. This paper proposed a thermal and visual analysis of the behavior of a Type IV fluid subjected to light freezing rain. During the precipitation, the plate temperature is measured with thermocouples and recorded using a visual camera and an IR camera. The use the visual camera in conjunction with the IR camera allowed to understand how the water drops interacted with the fluid and also to confirm the presence of frozen contaminants. The use of IR camera can be useful for the industry; however experimentation needs to be done before.
Brassard, Jean-Denis, Laforte, Caroline, Volat, Christophe
Summary of the High Ice Water Content (HIWC) RADAR Flight Campaigns2019-01-20276/10/2019
NASA and the FAA conducted two flight campaigns to quantify onboard weather radar measurements with in-situ measurements of high concentrations of ice crystals found in deep convective storms. The ultimate goal of this research was to improve the understanding of high ice water content (HIWC) and develop onboard weather radar processing techniques to detect regions of HIWC ahead of an aircraft to enable tactical avoidance of the potentially hazardous conditions. Both HIWC RADAR campaigns utilized the NASA DC-8 Airborne Science Laboratory equipped with a Honeywell RDR-4000 weather radar and in-situ microphysical instruments to characterize the ice crystal clouds. The purpose of this paper is to summarize how these campaigns were conducted and highlight key results. The first campaign was conducted in August 2015 with a base of operations in Ft. Lauderdale, Florida. Ten research flights were made into deep convective systems that included Mesoscale Convective Systems (MCS) near the Gulf of Mexico and Atlantic Ocean, and Tropical Storms Danny and Erika near the Caribbean Sea. The radar and in-situ measurements from these ten flights were analyzed and correlations defined. Key results included 1) derived relationships between radar reflectivity factor (RRF), Ice Water Content (IWC), and ice particle size distributions, 2) characterization of HIWC conditions at the -50°C and other flight levels, and 3) verification of pilot observations, such as low radar reflectivity factor and pitot and total air temperature (TAT) anomalies. This data set also enabled new pilot radar HIWC detection algorithms to be developed and tested. A second campaign was conducted in August 2018 to test proposed HIWC radar detection algorithms within a new set of storm systems. Seven research flights were conducted from bases of operations in Ft. Lauderdale, Florida; Palmdale, California; and Kona, Hawaii. Flights were made into convective systems over the Gulf of Mexico and into an eastern-Pacific tropical system that developed into Hurricane Lane. Using a new, NASA-developed radar processing technique called “Swerling”, regions of HIWC were identified, and estimates of IWC were produced, at distances up to 60 Nm ahead of the NASA DC-8. Subsequently, the DC-8 flew through these regions to acquire the in-situ measurements to verify the radar-based IWC estimates.
Ratvasky, Thomas, Harrah, Steven, Strapp, J. Walter, Lilie, Lyle, Proctor, Fred, Strickland, Justin, Hunt, Patricia, Bedka, Kristopher, Diskin, Glenn, Nowak, John B., Bui, T. P., Bansemer, Aaron, Dumont, Christopher
Extension of a 2D Algorithm for Catch Efficiency Calculation to Three Dimensions2019-01-20136/10/2019
Accurate calculation of the catch efficiency β is of paramount importance for any ice accretion calculation since β is the most important factor in determining the mass of ice accretion. A new scheme has been proposed recently in [1] for accurately calculating β on a discretized two-dimensional geometry based on the results of a Lagrangian droplet trajectory integrator (start and impact conditions). This paper proposes an extension to the algorithm in Ref. [1], which is applicable to three-dimensional surfaces with arbitrary surface discretization. The 3D algorithm maintains the positive attributes of the original 2D algorithm, namely mass conservation of the impinging water, capability to deal with overlapping impingement regions and with crossing trajectories, computational efficiency of the algorithm, and low number of trajectories required to reach good accuracy in catch efficiency. At the same time, the new 3D algorithm avoids typical difficulties of other approaches to determine the catch efficiency β, like noisy β (results varying significantly between neighboring surface cells), catch efficiency of zero for surface cells surrounded by other cells with β > 0, jagged impingement limits, catch efficiency β not available on the discretized surface but only on an intermediate plane, or interpolation problems of β between an intermediate plane and the actual discretized surface. The paper first reviews existing approaches in the literature to determine β, then describes in detail the extension of the algorithm in [1] to three dimensions and the steps taken to avoid the possible pitfalls in calculating β described above. The algorithm is then applied to two test problems, one being the wing/belly-fairing intersection of the Common Research Model (CRM) in clean configuration [2] and the other being a generic scoop intake. The paper closes with ideas for further development of the algorithm.
Bartels, Christian, Neubauer, Thomas, Hassler, Wolfgang
An Explorative Study to Use Super-Hydrophilic/Super-Hydrophobic Hybrid Surfaces for Aircraft Icing Mitigation2019-01-19956/10/2019
An explorative study was performed to demonstrate the feasibility of using a novel hybrid anti-/de-icing strategy for aircraft icing mitigation. The hybrid method was developed by combining the electro-thermal heating mechanism and specialized surfaces/coatings with different wettabilities. While an electrical film heater was utilized to provide thermal energy around the leading edge of a NACA0012 airfoil model, two different coating strategies, (i.e., (a). Superhydrophobic coating covering the entire airfoil surface to increase droplets bounce-off and accelerate surface water runback vs. (b). super-hydrophilic coating at the leading edge to increase evaporation area + superhydrophobic coating in downstream to prevent runback refreezing) were proposed and evaluated aiming at maximizing the anti-/de-icing efficiency of the hybrid method. While a series of experiments were conducted to examine the dynamics of droplet impinging onto the different surfaces (i.e., superhydrophobic vs. super-hydrophilic), a comprehensive experimental study was carried out in the Icing Research Tunnel at Iowa State University (i.e., ISU-IRT) to evaluate the anti-/de-icing performance of the hybrid method with the different coating strategies. It was found that, while both of the coating strategies could promote better anti-/de-icing performance of the hybrid method in comparison to the conventional heating-only method at rime ice condition. For glazed ice condition, the use of superhydrophobic coating over the entire airfoil surface would result in a maximized anti-/de-icing efficiency of the hybrid method (i.e., achieve a complete ice prevention with only 3% chord length covered with the electrical film heater), attributing to the significant droplets bounce-off and accelerated surface water runback behaviors.
Hu, Haiyang, Hu, Hui, Liu, Yang
A Three-Layer Thermodynamic Model for Ice Crystal Accretion on Warm Surfaces: EMM-C2019-01-19636/10/2019
Ingestion of high altitude atmospheric ice particles can be hazardous to gas turbine engines in flight. Ice accretion may occur in the core compression system, leading to blockage of the core gas path, blade damage and/or flameout. Numerous engine powerloss events since 1990 have been attributed to this mechanism. An expansion in engine certification requirements to incorporate ice crystal conditions has spurred efforts to develop analytical models for phenomenon, as a method of demonstrating safe operation. A necessary component of a complete analytical icing model is a thermodynamic accretion model. Continuity and energy balances are performed using the local flow conditions and the mass fluxes of ice and water that are incident on a surface to predict the accretion growth rate. In this paper, a new thermodynamic model for ice crystal accretion is developed through adaptation of the Extended Messinger Model (EMM) from supercooled water conditions to mixed phase conditions (ice crystal and supercooled water). A novel three-layer accretion structure is proposed and the underlying equations described. The EMM improves upon the original model for airframe icing, the Messinger Model, by permitting a linear temperature gradient through the ice and water layers. This in turn allows prediction of the time over which water exists in isolation on an initially warm surface, before an ice layer forms. This is of particular interest to engine icing, as surfaces may initially be significantly above freezing temperature, before cooling on exposure to ice particles. The method is solved in a multi-step approach, where the overall exposure time is divided into discrete windows, and the calculation performed over each window. This allows the local flow conditions to be updated between windows, permitting the incorporation of a reducing flow enthalpy due to particle evaporation, as well as transient engine operation. Model results are then compared to experimental results. Comparisons are made to solutions generated using the standard Messinger Model.
Bucknell, Alexander, McGilvray, Matthew, Gillespie, David, Jones, Geoffrey, Collier, Benjamin
An Eulerian Approach with Mesh Adaptation for Highly Accurate 3D Droplet Dynamics Simulations2019-01-20126/10/2019
Two main approaches are available when studying droplet dynamics for in-flight icing simulations: the Lagrangian approach, in which each droplet trajectory is integrated until it impacts the vehicle under study or when it leaves it behind without impact, and the Eulerian approach, where the droplet dynamics is solved as a continuum. In both cases, the same momentum equations are solved. Each approach has its advantages. In 2D, the Lagrangian approach is easy to code and it is very efficient, particularly when used in combination with a panel method flow solver. However, it is a far less practical approach for 3D simulations, particularly on complex geometries, as it is not an easy task to accurately determine the droplet seeding region without a great number of droplet trajectories, dramatically increasing the computing cost. Converting the impact locations into a water collection distribution is also a complex task, since droplet trajectories in 3D can follow convoluted paths. One of the advantages of the Lagrangian approach is the crisp definition of the shadow zone as it is clearly defined by the first trajectory to graze the surface of the vehicle. The Eulerian approach is much simpler to use with complex geometries, solving the entire domain as a whole, using the same grid as for the airflow, and there is no need to seed trajectories. For this reason, it is the preferred approach in most 3D icing solvers. One of its disadvantages, however, is that discontinuities, such as shadow zone limits or impingement limits, are usually not very sharply defined, with smoothing due to numerical dissipation and the grid, optimized heuristically for the airflow calculation, not being sufficiently fine in regions of solution discontinuities in the droplet solution. This paper presents a refined approach in the use of Eulerian algorithms for icing simulations by introducing a mesh adaption process simultaneously based on the airflow solution and the droplet solution. The results show the great potential of this approach in capturing the solution discontinuities very sharply, significantly reducing the uncertainty in determining shadow zone heights and impingement limits.
Pueyo, Alberto, Ozcer, Isik, Baruzzi, Guido
Numerical Modelling of Primary and Secondary Effects of SLD Impingement2019-01-20026/10/2019
A CFD simulation methodology for the inclusion of the post-impact trajectories of splashing/bouncing Supercooled Large Droplets (SLDs) and film detachment is introduced and validated. Several scenarios are tested to demonstrate how different parameters affect the simulations. Including re-injecting droplet flows due to splashing/bouncing and film detachment has a significant effect on the accuracy of the validations shown in the article. Validation results demonstrate very good agreement with the experimental data. This approach is then applied to a full-scale twin-engine turboprop to compute water impingement on the wings and the empennage. Since the performance characteristics of twin-engine commercial turboprops are such that they operate most efficiently at flight levels where SLD encounters may occur, the goal of this article is to establish a 3D computational methodology to eventually enable a complete study of the impact of FAR 25 Appendix O on the IPS requirements for this class of airplanes. The Appendix O icing conditions used for the demonstration of the methodology are set for a turboprop in a typical holding pattern at 6,000 ft, 190 kts, and 5° angle of attack. The air static temperature is 268 K and the LWC is 0.3 g/m3. Freezing drizzle environments are considered for the MVD > 40-micron droplet distributions. The results for these flight conditions show that inclusion of the secondary impingement due to splashing/bouncing in the simulation accounts for an increased water catch by 4.12% on the wing inboard section and 7.61% on the vertical stabilizer.
Fouladi, Habibollah, Baruzzi, Guido S., Nilamdeen, Shezad, Ozcer, Isik
Motivation, Development and Verification of a Rapid 3D Lagrangian Impingement Code - Trajectory and Catch 3D+ (TAC3D+)2019-01-20116/10/2019
This paper details the motivation, development and validation of a rapid 3D Lagrangian impingement code, Trajectory and Catch 3D+ (TAC3D+). AeroTex’s motivation to develop a 3D Lagrangian method was primarily driven by the inherent mesh dependent dissipation effect found in their 3D Eulerian Water Catch code (EWC) [1]. Studies performed by AeroTex have shown that for geometries where there are aft impingement regions that are partly shadowed by a more forward impingement region, the level of water flux dissipation can be significant, particularly if the mesh is coarse and the impingement region is far aft. Examples of issues where this may be a particular issue would be impingement on a centerline aft mounted engine or the calculation of impingement on the wing root/belly fairing. The code has been developed around a modified version of the OpenFOAM Lagrangian solver. The analysis process consists of three main phases; a coarse droplet trajectory calculation to identify the region of interest, a refined trajectory calculation that is sufficiently fine to calculate local water collection and a surface water collection efficiency calculation including mass loss due to splash and bounce associated with large droplets where applicable. The code allows the user to utilize multiple cluster queues to spread the job across multiple compute nodes to deliver the solution rapidly. The TAC3D+ code has been verified against a selection of 2D and 3D cases including some incorporating splash and bounce effects. The code is undergoing further development to incorporate the physics associated with ice crystals and the re-impingement of splashed particles. In addition, AeroTex are exploring methods to make the code even more efficient by maximizing time steps, utilizing different integration schemes and potential for the use of GPUs.
Roberts, Ian
Ice Nucleation in the Presence of Electric Fields: An Experimental Study2019-01-20206/10/2019
In the present study, ice nucleation in sessile water drops during continuous cool down is studied experimentally under the impact of a constant electric field, to determine its influence on heterogeneous nucleation. The experimental setup enables simultaneous observation of multiple drops under well-defined conditions with and without an electric field and at temperatures down to -40 °C. A single experimental run contains 40 drops exposed to the same conditions. Drops with a well-defined size are produced employing a drop-on-demand drop generator. Based on multiple experimental runs using the same drops, the nucleation behavior is analyzed using statistical methods to determine the drop survival curves and nucleation site densities for varying conditions. Besides the influence of the electric field, the influence of different drop ensembles is investigated for a constant cooling rate of 5 K/min. A comparison of the experiments with and without an electric field is used to elaborate its influence on heterogeneous ice nucleation.
Löwe, Jens-Michael, Schremb, Markus, Hinrichsen, Volker, Tropea, Cameron
Predicted Ice Shape Formations on a Boundary Layer Ingesting Engine Inlet2019-01-20256/10/2019
Computational ice shapes were generated on the boundary layer ingesting engine nacelle of the D8 Double Bubble aircraft. The computations were generated using LEWICE3D, a well-known CFD icing post processor. A 50-bin global drop diameter discretization was used to capture the collection efficiency due to the direct impingement of water onto the engine nacelle. These discrete results were superposed in a weighted fashion to generate six drop size distributions that span the Appendix C and O regimes. Due to the presence of upstream geometries, i.e. the fuselage nose, the trajectories of the water drops are highly complex. Since the ice shapes are significantly correlated with the collection efficiency, the upstream fuselage nose has a significant impact on the ice accretion on the engine nacelle. These complex trajectories are caused by the ballistic nature of the particles and are thus exacerbated as particle size increases. Shadowzones are generated on the engine nacelle, and due to the curvature of the nose of the aircraft the shadowzone boundary moves from lower inboard to upper outboard as particle size increases. The largest particle impinging one the engine nacelle from the 50-bin discretization was the 47 μm drop diameter. As a result, the MVD greater than 40 μm Appendix O conditions were characterized by extremely low collection efficiency on the engine nacelle for these direct impingement simulations.
Porter, Christopher
Icing Test and Measurement Capabilities of the NRC’s Gas Turbine Laboratory2019-01-19436/10/2019
The National Research Council’s Gas Turbine Laboratory provides industry leading icing facilities that allow manufacturers to develop, validate and certify new products for flight in adverse conditions. This paper shows how NRC measurement techniques are used across the facilities, and presents a literature-review of recently developed capabilities. The overview includes new details on some facilities, and future capabilities that are in development or planned for the near future. Methods developed at the NRC for characterizing inclement conditions are discussed and include the Isokinetic Probe, Particle Shadow Velocimetry, the Particle Detection Probe, and a size-binned real-time thermodynamic evaporation model. These are used to deliver accurate icing water content in facilities like the sea-level ice crystal generator, the Rotating Icing Rig, the Research Altitude Testing Facility, and liquid water test facilities in Ottawa and in Thompson, Manitoba at the Global Aerospace Centre for Icing and Environmental Research (GLACIER).
Chalmers, Jennifer, Davison, Craig, MacLeod, James, Neuteboom, Martin, Fuleki, Dan
SLD and Ice Crystal Discrimination with the Optical Ice Detector2019-01-19346/10/2019
In response to new safety regulations regarding aircraft icing, Collins Aerospace has developed and tested an Optical Ice Detector (OID) capable of discriminating among icing conditions appropriate to Appendix C and Appendix O of 14 CFR Part 25 and Appendix D of Part 33. The OID is a short-range, polarimetric lidar that samples the airstream up to ten meters beyond the skin of the aircraft. The intensity and extinction of the backscatter light correlate with bulk properties of the cloud, such as water content and phase. Backscatter scintillation (combined with the outside air temperature from another probe) signals the presence of supercooled large droplets (SLD) within the cloud-a capability incorporated into the OID to meet the requirements of Appendix O. Recent laboratory and flight tests of the Optical Ice Detector have confirmed the efficacy of the OID to discriminate among the various icing conditions. Drizzle-sized droplets, mixed with a small droplet cloud in the Collins Cloud Chamber, appear as scintillations in the lidar signal when it is processed pulse-by-pulse. Averaging the signal over multiple pulses, causes large droplets to become obscured by the small droplet background. In addition, the OID has discriminated and quantified mixed phase in a flight test aboard the NASA DC-8 Airborne Science Laboratory. The threshold for ice water quantification is less than 0.5 g/m3 IWC, while that for liquid water cloud detection is less than 0.05 g/m3 LWC.
Anderson, Kaare J., Ray, Mark D.
Microwave Technique for Liquid Water Detection in Icing Applications2019-01-19306/10/2019
The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion in the sub-gram range. The results indicate the potential of the technique, with a number of avenues evident for further research.
Leis, John, Buttsworth, David, Saeed, Ramiz, Saleh, Khalid, McGilvray, Matthew, Gillespie, David
Simulations of Thin Film Dynamics on a Flat Plate and an Airfoil2019-01-19386/10/2019
The goal of the present study is to investigate the dynamics of a thin water film on a flat plate and an airfoil using direct numerical simulation (DNS). The first case for a wetted flat plate is used to model former experiments and investigate the dynamics of a wind-driven water film. The second case for a thin film on a NACA 0012 airfoil of chord length 0.5 m is used to investigate the dynamics of a wind-driven water film on a curved surface. Particular attention is paid to the interaction between the liquid film and the air shear-layer above the film. As the incoming airflow moves over the thin water film, instability is triggered at the gas-liquid interface. Interfacial waves develop and are advected downstream. The interaction between the air flow and the interfacial waves induces shedding vortices near the interface, which in turn perturb the liquid film farther downstream. Simulations are performed using the open source multiphase flow solvers, Gerris and Basilisk. Both solvers employ a finite-volume approach and the interface is captured using a Volume-of-Fluid (VOF) method. While the long-term goal of this research effort is to investigate glaze ice formation in water films on airfoils, the current simulations focus on liquid film dynamics starting with a constant thickness exposed to a relatively low flight airspeed. The resulting simulations demonstrate the unsteady film dynamics and thickness evolution and natural waviness generated by the liquid-film and free-stream flow interactions.
Sakakeeny, Jordan, McClain, Stephen T., Ling, Yue
An Experimental Investigation of a Wind-Driven Water Droplet over the Slippery Liquid Infused Porous Surface2019-01-19516/10/2019
The promising anti-icing performance of the slippery liquid infused porous surface (SLIPS) has been recently demonstrated for various engineering applications. The runback icing for aircraft and wind turbines could be effectively mitigated considering the timely removal of water droplet by the wind shearing force due to the low adhesion on the SLIPS. In this study, the flow field both inside and around the wind-driven droplet over the SLIPS was experimentally investigated by using Particle Image Velocimetry (PIV) technique. Previous studies majorly focus on the internal flow pattern before the droplet incipient motion. In this study, the flow field inside a moving droplet was firstly investigated. As a result of the low surface adhesion of the SLIPS, droplet oscillations were eliminated and the droplet internal flow field could be corrected from the optical distortion. Besides the discussion on the wind speed, the droplet viscosity was also studied by varying the water concentration of the glycerin-water solution. It was found that the internal circulation was highly related with the droplet viscosity. The inner circulations within the water droplet would be reduced, or eliminated, when the droplet viscosity was increased, which would change the droplet motion from sliding into rolling. It was suggested that the internal flow should be considered when theoretically modeling the wind-driven droplet movement over the SLIPS. This study could provide experimental evidence for a broader application of the SLIPS in the icing-related industrial world.
Ma, Liqun, Hu, Hui
Uncertainty of the Ice Particles Median Mass Diameters Retrieved from the HAIC-HIWC Dataset: A Study of the Influence of the Mass Retrieval Method2019-01-19836/10/2019
In response to the ice crystal icing hazard identified twenty years ago, aviation industry, regulation authorities, and research centers joined forces into the HAIC-HIWC international collaboration launched in 2012. Two flight campaigns were conducted in the high ice water content areas of tropical mesoscale convective systems in order to characterize this environment conducive to ice crystal icing. Statistics on cloud microphysical properties, such as Ice Water Content (IWC) or Mass Median Diameter (MMD), derived from the dataset of in situ measurements are now being used to support icing certification rulemaking and anti-icing systems design (engine and air data probe) activities. This technical paper focuses on methodological aspects of the derivation of MMD. MMD are estimated from PSD and IWC using a multistep process in which the mass retrieval method is a critical step. Complementary to previous studies reporting on MMD values calculated from the HAIC-HIWC dataset, this paper deals with the uncertainty in MMD by comparing two different approaches for the retrieval of the mass-size (m-D) relationship. The analysis encompasses the data collected in the high IWC areas (IWC > 1g.m-3) sampled during the two HAIC-HIWC field campaigns. MMD series are computed using three different mass-size relationships and statistical values are compared. Overall, MMD values are in good agreement, at least for two methods although they imply quite different assumptions. On the variability in MMD values at a given temperature level, results show that MMD may vary significantly from one flight to the other, even though MMD series produced with the different mass retrieval methods follow a similar pattern. A strong temperature dependence is observed regardless the assumption on the m-D relationship, making MMD to increase by more than a factor of 2 as temperature increases from -50°C to -10°C. Finally, the influence on calculated MMD of two different definitions for particle size (Deq and Dmax) is demonstrated. Generally, MMD computed with Dmax are a few percent larger as compared to MMD calculated from Deq definition, supporting the conclusions from previous studies.
Coutris, Pierre, Schwarzenboeck, Alfons, Leroy, Delphine, Grandin, Alice, Dezitter, Fabien, Strapp, J. Walter
Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment2019-01-03154/2/2019
Increased in-cylinder hydrogen levels have been shown to improve burn durations, combustion stability, HC emissions and knock resistance which can directly translate into enhanced engine efficiency. External fuel reformation can also be used to increase the hydrogen yield. During the High-Efficiency, Dilute Gasoline Engine (HEDGE) consortium at Southwest Research Institute (SwRI), the potential of increased hydrogen production in a dedicated-exhaust gas recirculation (D-EGR) engine was evaluated exploiting the water gas shift (WGS) and steam reformation (SR) reactions. It was found that neither approach could produce sustained hydrogen enrichment in a real exhaust environment, even while utilizing a lean-rich switching regeneration strategy. Platinum group metal (PGM) and Ni WGS catalysts were tested with a focus on hydrogen production and catalyst durability. Although 4% additional hydrogen was initially produced in the EGR stream, leading to improvements in the coefficient of variation (CoV) and brake specific fuel consumption (BSFC), catalyst activity decreased within a few hours regardless of the regeneration strategy employed. With an SR catalyst, a small amount of hydrogen was produced in the EGR stream via the WGS reaction but not the SR reaction. Similar to the WGS catalyst testing, the SR catalyst deactivated quickly due to coking. While neither of these approaches displayed acceptable long-term performance, the exhaust environment still poses a significant opportunity for the production of hydrogen rich reformate to deliver improvement in engine efficiency.
Bartley, Gordon, Gukelberger, Raphael, Henderson, Robert, Henry, Cary
Regional Hydrologic Extremes Assessment System (RHEAS) SoftwareTBMG-341454/1/2019
Drought is Africa’s principal type of natural disaster and is at the core of serious threats to the livelihoods of millions of people and the natural resources on which they depend. The economies of many African countries are based on agricultural activities that are controlled mainly by rainfall amounts and distribution; thus, food security in the region is highly vulnerable to impacts of drought.
Theoretical Modeling of the Mechanical Degradation of Polymer Composites due to Moisture/Water Absorption and Damage Progression2019-01-13763/19/2019
The moisture/water absorption and microvoids/cracks progression are two well-understood mechanisms that have significant degradation effects on the mechanical properties/behaviors of the polymer-based composites. To theoretically investigate the effects of above two mechanisms, we develop a simple fiber reinforced polymer composites model by employing the internal state variable (ISV) theory. The water content and the anisotropically distributed damage of the composites are considered as two ISVs (the water content is described by a scalar variable and the damage is defined as a second order tensor) whose histories are governed by two specific physically-based evolution equations. The proposed model can be easily cast into a general theoretical framework to capture more polymer composites behaviors such as viscoelasticity, viscoplasticity and the thermal effect. The results predicted by current model are in good agreement with the experimental data, which allows us to implement the model into FEA for future structural analysis.
He, Ge, Liu, Yucheng
Contaminants Affecting the Formation of Soft Particles in Bio-Based Diesel Fuels during Degradation2019-01-00161/15/2019
Renewable fuels are essential in the field of heavy duty transportation if we are to reach a fossil-free society in the foreseeable future. However renewable diesel fuels based on fatty acid methyl ester (FAME) might face problems with degradation and with cold flow properties. From the perspective of an engine, this may cause problems in the fuel injection system, such as fuel filter clogging and injector deposits. These phenomena, especially fuel filter clogging, can be connected to gel-like soft particles, which could originate from degradation products as well as from byproducts created during biodiesel refining. In this study, soft particles from the degradation of bio-based diesel fuel were examined. The tested fuels included hydrogenated vegetable oils (HVO), rapeseed methyl ester (RME) and 10% blend of rapeseed methyl ester with standard diesel (B10). To test their potential to increase the formation of soft particles, contaminants such as water, metals and engine oil were included in the degradation methods. The formed insoluble products were analyzed with gravimetric means, scanning electron microscopy (SEM/EDX) and spectroscopy methods (FTIR). The results showed different behavior for each of the tested fuels. B10 was shown to be the most problematic, with the creation of gel-like soft particles. RME was less prone to create particles, probably due to its good solubility properties. HVO created the least sediments, possibly due to its high stability. According to the FTIR measurements, the captured insoluble sediments mainly consisted of polymerized oxidation products, acids and metal carboxylic ions. The type of metal influenced the chemical composition and the amount of insoluble sediment. Engine oil caused an increase in the amount of sediments. However the results also suggest that oil has a dampening effect for reactions between metals, water and fuels.
Csontos, Botond, Alim, Richard, Bernemyr, Hanna, Hittig, Henrik, Pach, Mayte
Water Injection Benefits in a 3-Cylinder Downsized SI-Engine2019-01-00341/15/2019
With progressing electrification of automotive powertrains and demands to meet increasingly stringent emission regulations, a combination of an electric motor and downsized turbocharged spark-ignited engine has been recognized as a viable solution. The SI engine must be optimized, and preferentially downsized, to reduce tailpipe CO2 and other emissions. However, drives to increase BMEP (Brake Mean Effective Pressure) and compression ratio/thermal efficiency increase propensities of knocking (auto-ignition of residual unburnt charge before the propagating flame reaches it) in downsized engines. Currently, knock is mitigated by retarding the ignition timing, but this has several limitations. Another option identified in the last decade (following trials of similar technology in aircraft combustion engines) is water injection, which suppresses knocking largely by reducing local in-cylinder mixture temperatures due to its latent heat of vaporization. Addition of adequate water can lead to stoichiometric air/fuel ratio engine operation, and hence both reduction in fuel consumption and full utilization of a three-way catalytic converter (TWC). Further information about effects of various water injection parameters is required. Thus, in this study, a 4-stroke, 1.5 liter, 3-cylinder turbocharged engine with direct fuel injection and port water injection was operated on 91, 95 and 98 RON gasoline fuel to assess effects of water injection on knock mitigation, combustion phasing, required air:fuel ratios and exhaust gas temperature control. Full- and part-load curves obtained with different fuels and water injection strategies are presented and discussed.
Khatri, Jayesh, Denbratt, Ingemar, Dahlander, Petter, Koopmans, Lucien
NOx-Conversion Comparison of a SCR-Catalyst Using a Novel Biomimetic Effervescent Injector on a Heavy-Duty Engine2019-01-00471/15/2019
NOx pollution from diesel engines has been stated as causing over 10 000 pre-mature deaths annually and predictions are showing that this level will increase [1]. In order to decrease this growing global problem, exhaust after-treatment systems for diesel engines have to be improved, this is especially so for vehicles carrying freight as their use of diesel engines is expected to carry on into the future [2]. The most common way to reduce diesel engine NOx out emissions is to use SCR. SCR operates by injecting aqueous Urea solution, 32.5% by volume (AUS-32), that evaporates prior the catalytic surface of the SCR-catalyst. Due to a catalytic reaction within the catalyst, NOx is converted nominally into Nitrogen and Water. Currently, the evaporative process is enhanced by aggressive mixer plates and long flow paths. The mixer plates create extra exhaust back pressure and cool the exhaust gases, which decreases engine and catalyst efficiency, resulting in overall poor NOx conversion (<40%) and higher CO2 production under real life drive cycle conditions. To achieve future emission legislation targets, SCR efficiency has to be improved, especially under low catalyst temperature conditions. It should also be noted that Ammonia slip has to be avoided as it is now legislated against [3]. In this study a novel biomimetic effervescent aqueous urea injector, its design inspired by the natural spray phenomenon of the Bombardier Beetle, is used to compare against a market-leading aqueous urea doser in comparable exhaust conditions with and without aggressive mixer plates being installed. The novel biomimetic effervescent injector operates by increasing the temperature of the Urea solution inside a constant volume chamber to its saturated vapour pressure. At the required time of injection an electromagnetically controlled outlet valve opens exposing the now superheated fluid to lower pressure conditions, this results in a hot, effervescent spray being ejected which rapidly breaks up into very fine droplets (<20um) projected at high velocity (60m/s) into the exhaust stream targeted at the face of the SCR catalyst. The novel biomimetic effervescent injector shows great potential with a significant higher NOx conversion rate and lower ammonia slip compared to the market-leading doser on a heavy-duty engine.
Larsson, Peter, Ravenhill, Paul, Tunestal, Per
Products of Tomorrow: January 2019TBMG-335941/1/2019
This column presents technologies that have applications in commercial areas, possibly creating the products of tomorrow. To learn more about each technology, see the contact information provided for that innovation.
Water Load Determination Approach in Two Wheeler Exhaust System2018-32-007510/30/2018
Future emission norms in India (BS6) necessitates the 2 wheeler industry to work towards emission optimization measures. Engine operation at stoichiometric Air-Fuel Ratio (AFR) would result in a good performance, durability and least emissions. To keep the AFR close to stoichiometric condition, an Oxygen sensor is placed in the exhaust system, which detects if air-fuel mixture is rich (λ<1) or lean (λ>1) and provides feedback to fuel injection system for suitable fuel control. O2 sensor has a ceramic element, which needs to be heated to a working temperature for its functioning. The ceramic element would break (thermal shock) if water in liquid form comes in contact with it when the element is hot. To counter this, oxygen sensor is either fully heated only when all the water in the exhaust system is evaporated, which results in delayed closed loop control, or is capable to withstand higher amount of water in the exhaust system by for example being applied with thermal shock protection and a protective tube. It’s a challenge to control the HC emissions during first 100 seconds of engine start, as the catalyst is not functioning during this duration. Also, the system runs in open loop for first 50 seconds, as the lambda sensor is not functioning. Hence, determining the amount of water present in exhaust and having a protective layer for lambda sensor against water would enable early start of sensor functioning. The present paper explains an approach to determine the maximum water droplet size and water flow rate using a special Liquid sensor mounted in the exhaust pipe. Test cases are defined at various engine and exhaust gas temperatures to determine an appropriate set up and methodology for measurement on a 2Wheeler. The test cases are repeated on various 2wheelers available in the Indian market and influence of different exhaust configurations, mounting location of the Lambda sensor are analysed. The information of water droplet size and water flow rate are driving factors for the design and application of lambda sensor. With thermal shock protection over lambda sensor a full heater voltage can be applied to sensor even before all the water has evaporated in the exhaust system. An early sensor readiness results in a quick closed loop control of the fuel mixture thus reducing emissions.
Meena, Ranjana Kumari, Krusch, Andrea, Meister, Konrad, Holzknecht, Christopher
Evaluation of Atomization Timing and Optimal Water Content for an Emulsified Fuel Droplet2018-32-005910/30/2018
The emulsified fuel means that it is mixed fuel with water and stabilized by surfactant. The difference of boiling points between fuel and water occur the secondary atomization during heating process. The water content strongly influence on the timing of secondary atomization(1). However, the water content is determined empirically. It means that it is the doubtful of compatibility fuel and a combustor. Then the emulsified fuel is needed the engineering evaluation (not empirically) to take advantage of sure secondary atomization. This research focuses on the timing and behavior of secondary atomization with an emulsified fuel droplet and the proposal of engineering evaluation. Moreover, we propose novel test method without the suspending wire to avoid heat transfer from itself. Namely, the novel point is heating process by floating in the high temperature silicone oil. This method can reveal the atomization behavior of a fuel droplet similar to the spray combustion. The measured data are waiting time of atomization and direct photos during heating process. The waiting time is fitted by Weibull plots which is a statistical treatment of reliability engineering. The inclination of Weibull plots means the timing of secondary atomization. This is the engineering evaluation on this research. The experimental results show the optimal water content of n-Hexadecane is 23%. If the fuel droplets have different timing of the secondary atomization, it is hard to control the combustion, for example, ignition delay, rate of heat release and so on. The typical experimental results show the inclination of Weibull plots converge to a point. This is mean that even various sizes of fuel droplets occur secondary atomization in the similar timing during heating process. The optimal water content of Bio diesel fuel is wide range under 30%. We propose the statistical evaluation to determine the optimal water content for practical emulsified fuel use.
Aoki, Junichi, Tanaka, Junya
Effects of the Metal Surface Profile to the Sliding Properties between Rubber and Metal and Applying That to Wheel Bearing Seals2018-01-190410/5/2018
Cartridge seals are frequently utilized in wheel bearings where a high level of reliability is required. The cartridge seal combines two components; a seal with flexible rubber lips and a stamped metal slinger that provides a surface for the seal lips to contact without being exposed directly to foreign substances. This paper provides a fundamental evaluation of the sliding properties of rubber seal lips relative to the slinger metal surface profile and evaluates the performance of rotating torque and muddy water endurance from a recommend metal surface profile (developed by advanced fundamental evaluation) of the slinger. Seals with the recommend metal surface profile showed approximately 30% lower torque at the rotating speed from 400 rpm to 800 rpm, which are the speeds representative of automotive city driving. At the same time, the durability performance against muddy water was almost equivalent to the seals without this metal surface.
Ishida, Koki, Fujii, Masahiro, Cho, Jun Hwi, Pittel, Kevin
The Use of Ozone in Low Temperature Methane Control for Natural Gas Applications2018-01-17029/10/2018
Lean operating natural gas heavy duty applications have advantages in terms of lower CO2 and PM compared to Diesel applications. This makes operating heavy duty applications on natural gas attractive and currently, they do not have to implement an exhaust particulate filter. However, the challenge is controlling methane emissions over a range of vehicle operating conditions. Methane is extremely stable and light off occurs at temperatures above 400 °C, with high efficiency occurring >500 °C and requires high precious metal loaded catalysts in the range of 150 - 200 g/ft3. Under stoichiometric conditions, 500 °C can be met in many engine operating points however, for lean operating applications, the exhaust temperature can be significantly lower than 500 °C posing a significant challenge for exhaust catalytic CH4 control. This paper will discuss synthetic gas reactor study results using ozone in the feed gas to perform low temperature methane control. A range of catalysts were characterised for the development of low temperature methane control and a non-precious metal catalyst was found to give high efficiency at low temperatures. The best catalyst screened did not contain PGM and was a current production catalyst that gave >60% CH4 control at 220 °C, in the presence of water. All other catalysts screened gave no significant methane control activity at low temperatures. The feed gas composition played a key role in the peak efficiency obtained. The data shows a significant improvement in ozone enhanced catalysis compared to more traditional precious metal based CH4 control routes.
Keenan, Matthew, Nicole, Jacques, Poojary, Damodara
Effects of Clamping Force on the Operating Behavior of PEM Fuel Cell2018-01-17189/10/2018
Proton exchange membrane (PEM) fuel cell is widely recognized as an outstanding portable power plant and expected to be possibly commercialization in the near future. As is well known, mechanical stresses implemented on the bipolar plates during the assembly procedure should have prominent influences on mass and heat transfer behavior inside the cell, as well as the resultant performance. In this study, an analytical model is proposed to comprehensively investigate the influence of clamping force on the mass transport, electrochemical properties and overall cell output capability of a PEM fuel cell. The results indicate that proper clamping force not only benefits the gas leakage prevention but also increases the contact area between the neighboring components to decrease the contact ohmic resistance. However, deformation always takes place simultaneously, changing the local physical structures of the cell components, which possibly leads to the decrement of porosity and permeability of the gas diffusion layer (GDL) and catalyst layer (CL), hinders the gas species and liquid water transport in GDL, and also decreases the cross-sectional flow area in the channel. The combined effect of the aforementioned factors finally contributes to the cell performance fluctuation. Moreover, although the contact resistance decreases with increasing stresses, more significant mass transfer losses, e.g. lower membrane water content and larger gradient in liquid saturation, results in more serious concentration voltage losses and weaker proton conductivity in the membrane, further impairing the cell voltage output. Therefore, cell performance should be optimized by the balancing among the transport properties and the contact resistance involved in the fuel cell. By using this analytical model, optimal cell design parameters and clamping pressure exerted on the fuel cell can be quickly predicted accordingly. Proper discussions are carried out and suggestions are proposed.
Chen, Rouxian, Qin, Yanzhou, Du, Qing, Peng, Jun
Simulation of Intake Manifold Water Injection in a Heavy Duty Natural Gas Engine for Performance and Emissions Enhancement2018-01-16539/10/2018
The present work discusses the effects of intake manifold water injection in a six-cylinder heavy duty natural gas (NG) engine through one-dimensional simulation. The numerical study was carried out based on GT-Power under different engine working conditions. The established simulation model was firstly calibrated in detail through the whole engine speed sweep under full load conditions before the model of intake manifold water injector was involved, and the calibration was based on experimental data. The intake manifold water injection mass was controlled through adjustment of intake water/gas (water/natural gas) ratio, a water/gas ratio swept from 0 to 4 was selected to investigate the effects of intake manifold water injection on engine performance and emissions characteristics. On the other hand, the enhancement potential of intake manifold water injection in heavy duty NG engine under lean and stoichiometric condition was also investigated by the alteration of air-fuel ratio. The calculation results demonstrated that in considering maximum performance enhancement strategy preferentially, the engine performance characteristics was increased around 3% under lean condition while 7%-10% at stoichiometric condition, with a drastic NOX emissions reduction capability around 70%-80%. When took minimum NOX emissions as a primary consideration for water injection strategy, over 90% of NOX emissions at lean condition and 80% of NOX emissions at stoichiometric condition could be eliminated with performance characteristics and BSFC deterioration less than 10%. To achieve optimized engine performance and emissions characteristics simultaneously, the optimum engine control strategy with intake manifold water injection could be attained through an advanced spark timing while maintaining water/gas ratio the same as the minimum NOX emissions strategy.
Kang, Zeqi, Kang, Zhe, Jiang, Lang, Deng, Jun, Wu, Zhijun, Li, Liguang, Liang, Heping, Shu, Mingyu
Effect of Water Injection and Spatial Distribution on Combustion, Emission and Performance of GDI Engine-A CFD Analysis2018-01-17259/10/2018
Water injection in diesel engines is a successful way to reduce NOx emissions and enhance brake power output. The advantages of water injection are because of its high enthalpy of vaporization and high specific heat capacity by which it absorbs heat from the in-cylinder mixture. The benefits of water injection depend on the rate of water vaporization and its spatial distribution in the combustion chamber. However, detailed effects of these parameters are very rarely studied in the past. Therefore, in the present study, an attempt has been made to assess the effect of water injector configuration on performance of a GDI engine by CFD analysis. Here, the analysis is done mainly to study and enhance the evaporation and spatial distribution characteristics of the water injection inside the combustion chamber. Water is directly injected into the cylinder of a naturally aspirated, four-stroke GDI engine. Various water injection configurations formed by different spray patterns and injector orientations are considered for the study and compared with a no water case. The analysis is done under full-load conditions with a constant engine speed of 2000 rev/min. The CFD models used in this study are validated from the available data in the literature. From the results, it is found that the water spray pattern in a shape of the regular hexagon at an injector orientation of 25˚ produces higher IMEP with lower NOx and soot emissions.
Raut, Ankit Ashokrao, Mallikarjuna, J M
HOSE ASSEMBLY, LINED SILICONE, 125 PSI, FLARELESS TO FIXED CAVITY, POTABLE WATERAS5503B (Current)8/14/2018
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Water-Based Battery Stores Solar and Wind EnergyTBMG-324768/1/2018
Wind and solar energy generation creates challenges, since the Sun only shines by day, and sometimes the wind doesn't blow. Another variability is surges of demand on the grid. On a hot day when air conditioning is in use, utilities must have load-balancing strategies to meet peak demand. A water-based battery was developed that could provide a cheap way to store wind or solar energy generated when the Sun is shining and wind is blowing so it can be fed back into the electric grid and be redistributed when demand is high.
Artificial “Blubber” Protects Divers in Frigid WaterTBMG-324828/1/2018
When Navy SEALs carry out dives in Arctic waters, or when rescue teams are diving under ice-covered rivers or ponds, the survival time even in the best wetsuits is very limited — as little as tens of minutes. Researchers have discovered a process to triple that survival time.
Reducing Moisture in Natural FibersTBMG-297197/1/2018
Biological transformation focuses on the sustainable use of biological resources such as plants or microorganisms. In the future, it is expected to reduce reliance on fossil fuels such as oil, coal, or gas, and help tackle major challenges such as climate change and global population growth. It offers options and opportunities for almost all industries. One field of application for biological resources is materials such as natural fiber reinforced plastics (NFRP).
Splashing Criterion and Topological Features of a Single Droplet Impinging on the Flat Plate2018-01-02894/3/2018
This paper aims to provide the experimental and numerical investigation of a single fuel droplet impingement on the different wall conditions to understand the detailed impinging dynamic process. The experimental work was carried out at the room temperature and pressure except for the variation of the impinged wall temperature. A high-speed camera was employed to capture the silhouette of the droplet impinging on wall process against a collimated light. Water, diesel, n-dodecane, and n-heptane were considered as four different droplets and injected from a precision syringe pump with the volume flow rate of 0.2 mL/min at various impact Weber numbers. The impingement outcomes after droplet impacting on the wall include stick, spread, rebound and splash, which depend on the controlling parameters of Weber number, Reynolds number, liquid and surface properties, etc. In this paper, the various splashing and non-splashing criteria were summarized based on the earlier research and applied to evaluate the current experimental data. It is found that the experimental results at various conditions overall show good agreement in predicting the splashing and non-splashing phenomena with existing droplet-wall interaction models. A new correlation of deposition-splashing in terms of the current experimental data is developed. Further, the effects of the impact Weber number, surface temperature, and surface roughness on the time evolution of droplet spreading factor, height ratio, the dynamic contact angle, and the contact line velocity were studied to aid in the development of a dynamic contact angle model. Finally, the volume of fluid (VOF) method was considered to characterize the single fuel droplet impinging on the wall and provide a better understanding of the dynamic impingement process in the CONVERGE™ framework. The simulation results of the spreading factor, height ratio, and the contact angle match well with the experimental results during the droplet impingement process.
Zhao, Le, Ahuja, Nitisha, Zhu, Xiucheng, Zhao, Zhihao, Lee, Seong-Young
Experimental Investigation of Novel Ammonia Mixer Designs for SCR Systems2018-01-03434/3/2018
Meeting Euro 6d NOx emission regulations lower than 80 mg/km for light duty diesel (60 mg/km gasoline) vehicles remains a challenge, especially during cold-start tests at which the selective catalyst reduction (SCR) system does not work because of low exhaust gas temperatures (light-off temperature around 200 °C). While several exhaust aftertreatment system (EATS) designs are suggested in literature, solutions with gaseous ammonia injections seem to be an efficient and cost-effective way to enhance the NOx abatement at low temperature. Compared to standard SCR systems using urea water solution (UWS) injection, gaseous NH3 systems allow an earlier injection, prevent deposit formation and increase the NH3 content density. However non-uniform ammonia mixture distribution upstream of the SCR catalyst remains an issue. These exhaust gas/ NH3 inhomogeneities lead to a non-optimal NOx reduction performance, resulting in higher than expected NOx emissions and/or ammonia slip. Thus, efficient mixers upstream of the SCR are crucial for the overall EATS performance. In the experimental study reported in this article, planar laser induced fluorescence (PLIF) is used to quantify mixing performance of four novel CFD optimized static mixers in an optically accessible flow bench. The variation of boundary conditions and the change of exhaust line configurations (e.g. w/wo DOC upstream, w/wo DPF downstream) show a major effect on the mixing process and subsequently the homogeneity of the ammonia-exhaust gas mixture (for example: drop in uniformity index from UI = 0.95 to UI = 0.60 for a blade mixer design). This points out the need to purposefully design and optimize static mixers for a specific exhaust line configuration.
Schiffmann, Philipp, Lecompte, Matthieu, Laget, Olivier
Effects of Mass, Pressure, and Timing of Injection on the Efficiency and Emissions Characteristics of TSCI Combustion with Direct Water Injection2018-01-01784/3/2018
A CFD investigation has been conducted to study the efficiency and emissions characteristics of Thermally Stratified Compression Ignition (TSCI) combustion with direct water injection. The motivation for using this new low temperature combustion mode is its ability to control the heat release process by introducing a forced and controlled thermal stratification beyond what would occur naturally. In this case, TSCI is enabled using direct water injection. The added degree of control over the combustion process allows for a significantly broader operable load range compared to HCCI. The effects of injection parameters including the pressure, start of injection (SOI) timing, and spray pattern have been shown previously to affect the heat release of TSCI and its induced thermal stratification. In the present work, the efficiency and emissions considerations were investigated in detail, and the effects of injected mass are presented. A 3-D CFD model was simulated using CONCERGE CFD software. The results show that while there is never a large difference between the thermal efficiency of pure HCCI without water injection and TSCI with water injection, certain injection conditions can cause the combustion efficiency to decrease due to excessive forced thermal stratification, late combustion phasing, and longer burn durations. However, if the combustion phasing is controlled and the thermal stratification is not increased beyond the necessary level to control the heat release and pressure rise rates by tailoring the injection conditions, the TSCI combustion efficiency can be very similar to HCCI. Additionally, the results show that TSCI with water injection can cause a reduction of NOX emissions, while the UHC and CO emissions can increase when too much forced thermal stratification is introduced.
Rahimi Boldaji, Mozhgan, Sofianopoulos, Aimilios, Mamalis, Sotirios, Lawler, Benjamin
Parallel Thermal Management System of the Water Medium Retarder2018-01-07774/3/2018
The thermal management system of the water medium retarder using engine coolant (water and ethylene glycol) as transmission medium, omits oil-water heat exchanger in the structure. When the hydraulic retarder is operated, the valve is connected with the retarder and water pump, and then the engine coolant enters the working chamber. The kinetic energy of the vehicle is converted into internal energy of the coolant, and the heat is discharged to the external environment through the engine thermal management system. The braking torque of the water medium hydraulic retarder is determined by the water medium flow rate in the working chamber. The smaller the valve opening degree, the greater the braking torque and the faster the heating transmission fluid. Small valve opening is not conducive to the loss of heat. It will affect the normal working of the engine and hydraulic retarder. In this paper, the thermal management system of the water medium hydraulic retarder is independent of the engine. Hydraulic retarder can be controlled individually so that to improve the auxiliary braking performance. Firstly, the independent thermal management system is designed according to the heat dissipation requirement of the hydraulic retarder. Secondly, the heat transfer of the hydraulic retarder thermal management system is analyzed. Finally, compare to the thermal management system of the traditional water medium retarder and the paper. The results show that the thermal management system of parallel water medium hydraulic retarder can effectively use the radiator cooling capacity, and reduce the working temperature of the water hydraulic retarder.
Gao, Xin, Lei, Yulong, Chen, Wei, Cui, Guokai, Zhong, Lei
Development of Highly Durable Zeolites as Hydrocarbon Trap Materials for Automotive Catalysts2018-01-09474/3/2018
Low-temperature activity is an important requirement for automotive catalysts. In particular, most of the tailpipe emissions occur right after the engine starts (cold emissions). These emissions can be effectively reduced by using a trap material such as zeolite for hydrocarbon (HC) adsorption [1, 2, 3, 4, 5, 6, 7, 8, 9]. However, using zeolite as a trap material in automotive catalyst is limited due to its low durability under hydrothermal aging conditions. That is the reason why zeolites can be often used for diesel engines which usually run at lower temperature than the gasoline engines during entire mode driving. In most cases, zeolites need to be placed away from large thermal loads in order to take advantage of their adsorption abilities. In general, the thermal endurance of close-coupled catalysts for gasoline powered vehicles proceeds at about 1000 °C in the presence of water. Under these conditions, the zeolite structure would be decomposed by the dissociation of aluminum from the zeolite frameworks [10]. Through this study, we show that the hydrothermal durability of zeolite can be dramatically improved by chemical modification of zeolite with zirconium phosphate. This improvement strategy works well, especially for β-type zeolites (BEAs) with low SiO2/Al2O3 ratio, which can be easily decomposed by hydrothermal aging at around 1000 °C. We also found that this modified BEA worked well as HC trap material and showed an enormous reduction of cold HC emissions with Pd/Rh three-way catalyst (TWC). In the engine test evaluations with the close-coupled TWC + TWC and TWC + HC trap system as aged catalysts, effects of this HC trap catalyst on cold emissions were observed. It is found that HC emission decrease by up to 43% when compared to those from the corresponding TWC + TWC system which does not have any zeolite. In addition, a detailed analysis of this effect proved this improvement to be due to the adsorption-desorption process of zeolite and the purification process by TWCs.
Endo, Yoshinori, Nishikawa, Joe, Iwakura, Hironori, Inamura, Masaaki, Wakabayashi, Takashi, Nakahara, Yuunosuke, Ogasawara, Masataka, Kato, Sumio
Flexible, Water-Based Lithium-Ion BatteriesTBMG-287394/1/2018
Researchers have developed a lithium-ion battery that uses a water-salt solution as its electrolyte — reaching the 4.0- Volt mark for electronics such as laptops — without the fire and explosive risks associated with commercially available, non-aqueous lithium-ion batteries.
Printable Structures Self-Fold Without Heating or Immersion in WaterTBMG-281581/1/2018
As 3D printing has become a mainstream technology, studies have investigated printable structures that will fold themselves into useful three-dimensional shapes when heated or immersed in water. A new printable structure, however, was developed that begins to fold itself up as soon as it is peeled off the printing platform.
An Investigation of the Transient DPF Pressure Drop under Cold Start Conditions in Diesel Engines2017-01-237210/8/2017
To monitor emission-related components/systems and to evaluate the presence of malfunctioning or failures that can affect emissions, current diesel engine regulations require the use of on-board diagnostics (OBD). For diesel particulate filters (DPF), the pressure drop across the DPF is monitored by the OBD as the pressure drop is approximately linear related to the soot mass deposited in a filter. However, sudden acceleration may cause a sudden decrease in DPF pressure drop under cold start conditions. This appears to be caused by water that has condensed in the exhaust pipe, but no detailed mechanism for this decrease has been established. The present study developed an experimental apparatus that reproduces rapid increases of the exhaust gas flow under cold start conditions and enables independent control of the amount of water as well as the gas flow rate supplied to the DPF. The results show that the sudden decrease in the DPF pressure drop is caused by the water in the developed system used here. Observations of the soot cake layers in the DPF show that the decrease in the DPF pressure drop is caused by peeling-off and separation of the soot cake layer from the walls of the DPF. An increase in the water flow rate thins the soot cake layer and decreases the DPF pressure drop. Further, numerical simulation using a DPF model developed by a research group at Waseda University was also performed, and the calculated DPF pressure drop captures the changes obtained by the experiments well.
Kobashi, Yoshimitsu, Oooka, Shun, Jiang, Lin, Goto, Jun, Ogawa, Hideyuki, Shibata, Gen
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