Browse Topic: Pressure

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Study on the Optimal Pre-Chamber Geometry for Active Pre-Chamber Gas Engines2024-32-002304/18/2025
In a pre-chamber engine, fuel in the main-chamber is ignited and combusted by the combustion gas injected from the pre-chamber. Therefore, further fuel dilution is possible and thermal efficiency can be also improved. However, adding a pre-chamber to an engine increases the number of design parameters which have a significant impact on the main combustion and the exhaust gas. Then, in this study, the optimum geometry of the pre-chamber in an active pre-chamber gas engine was investigated. The considered parameters were the volume of pre-chamber, the diameter of a nozzle hole, and the number of nozzle holes. 18 types of pre-chambers with different geometries were prepared. Using these pre-chambers, engine experiments under steady conditions were conducted while changing the conditions such as engine speeds, mean indicated pressure and air excess ratio. Based on the experimental data, neural network models were constructed that predict thermal efficiency, NOx and CO emissions from the
Yasuda, Kotaro, Yamasaki, Yudai, Sako, Takahiro, Takashima, Yoshitane, Suzuki, Kenta
Technical Paper
Detailed Approach for Pre-Chamber Heat Release Analysis for the HSASI Pre-Chamber Spark Plug Using a Pressure Sensor Glow Plug2024-32-006304/18/2025
The hot surface-assisted spark ignition (HSASI) pre-chamber spark plug, which was developed at the Karlsruhe University of Applied Sciences, increases the dilution limit with excess air and the tolerance to residual gas in the pre-chamber compared to a conventional passive pre-chamber spark plug. In this study, the conventional glow plug which is integrated in the pre-chamber of the HSASI pre-chamber spark plug was replaced by a pressure sensor glow plug (PSG) from BERU. This allows for a detailed combustion analysis in the pre-chamber. The signal of the PSG was validated with a piezoelectric cylinder pressure sensor and a method to analyse the pre-chamber heat release was introduced. Experimental investigations were carried out on a single-cylinder gasoline engine. A series of operating points diluted with excess air and a variation in load were conducted. The gas flow rate through the orifices of the pre-chamber was calculated from the pressure difference between the pre-chamber and
Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland
Technical Paper
Experimental Investigation of n-C7H16/Ethanol Blended Fuels on Auto-ignition and Flame Propagation in High Temperature/Pressure Constant-Volume Combustion Vessel2024-32-005004/18/2025
This study aims to investigate the effect of ethanol blends on flame propagation and auto-ignition under high pressure and high temperature conditions. Experimental investigations are conducted using n-C7H16 / ethanol blends at various blending ratios (0, 5, 10, 20, 40, 70, and 100 vol%). The blends are premixed with air at stoichiometric ratios and ignited centrally in a cylindrical constant-volume combustion chamber (20-mm inner diameter, 80-mm long) under elevated temperature (500 K) and pressure (1.0 MPa) conditions. The results show that auto-ignition occurs at an ethanol blend ratio of 10% or less and ceases above 20%. Increasing the ethanol blend to 70% results in a slight change in flame propagation speed, with a noticeable delay at 100%. The pressure measurements show a peak of about 5.6 MPa at a blend ratio of 5%, which gradually decreases with increasing ratios. High-pass filtering reveals the maximum pressure fluctuation amplitude at the 5% blend ratio, indicating increased
Tateishi, Tokua, Yamaguchi, Riki, Shimokuri, Daisuke, Terashima, Hiroshi, Hara, Takaya, Honda, Yuya, Kawano, Michiharu
Technical Paper
SDPF Application DOE For BS6 RDE/OBD2 using MATLAB/SGB/ETB/CDT2024-26-016101/16/2024
To meet future emission levels, the industry is trying to reduce tailpipe emissions by both, engine measures and the development of novel catalytic emission control concepts. The present study will focus on the close coupled SCR on Filter commonly known as SDPF which is a main pathway to reduce NOx along with Particulate mass and number for light duty passenger cars and sport utility vehicles for BS 6 RDE/OBD 2 and future legislation like BS-7. SDPF is a challenging technology as it is critical component in exhaust after treatment system involving in NOx and PM/PN reductions hence careful optimization of this technology is necessary in terms of Space velocity requirements, Temperature profile wrt to NOx conversion, Raw NOx concentration, Particulate mass and Ash holding capacities, NH3 storage requirements, back pressure and so on. With BS6 RDE having extremely challenging CF for NOx equals to 1,43, the SDPF design & optimization is high on importance and to demonstrate the success of
Singh, Shephali, Patil, Sandip, Maynal, Rajesh A., Maske, Vidyasagar, Seyler, Michael, Subramanian, Senthilnathan, Deshpande, P V, Luquman, Shahid
Technical Paper
Soot sensor elimination with DPF substrate failure monitoring.2024-26-015301/16/2024
The automobile industry is going through one of the most challenging times, with increased competition in the market which is enforcing competitive prices of the products along with meeting the stringent emission norms. One such requirement for BS6 phase 2 emission norms is the inclusion of PM (Soot) sensor in diesel passenger cars. PM sensor detects soot leakage in case of DPF substrate failure. There is a cost factor along with extensive calibration efforts which are needed to ensure sensor works flawlessly. This paper deals with the development of an algorithm with which robust detection of DPF substrate failure is achieved. In order to achieve this, a thermodynamic model of DPF substrate was created using empirical relations between parameters like exhaust flow rate, exhaust gas temperature and soot mass content. The modeling was done in both empty (no soot) and filled (threshold soot content) substrate conditions. There were two methodologies, namely integration method and
Jain, Praveer Kirtimohan, Yadav, Omkar, Chendil, Chellapandi
Technical Paper
Improving Dynamic Response of PEMFC Anode Pressure in Droped Load Scenarios through Split Range Control2023-01-702610/30/2023
The dynamic response of proton exchange membrane (PEM) fuel cells’ anode pressure and the pressure difference between the cathode and anode significantly influence the performance and durability of fuel cells. To address the slow dynamic response of the anode pressure during rapid load drops, this study proposes a split range control strategy by introducing the hydrogen purge valve into the anode pressure control. By rational planning the split range block, the hydrogen purge valve is opened at appropriate times during load drops. To validate the effectiveness of the split range control, simulations are conducted under load drop conditions using an 80 kW fuel cell hydrogen and air supply subsystem model. The simulation results demonstrate that the split range control reduces the setting time of the anode pressure during load drops by half, with the most significant improvement observed at 67% load to idle condition, where the setting time is reduced from 2.6 s to 1.1 s. Furthermore
Zhang, Junyu, Chen, Fengxiang, Pei, Fenglai, Li, Tao, Xu, Shuo
Technical Paper
Characterize the Sound Field Generated from a Vehicle Horn by Pellicular Analysis2025-01-005805/05/2023
To predict the sound field produced by a vehicle horn requires a good source representation of it in the full vehicle model. This paper investigates the characterization of a physical vehicle horn by an inverse method called pellicular analysis. To implement this method, firstly an acoustic testing is performed to measure the sound pressure radiated from the horn at a certain number of microphone locations in a free field environment. Based on the geometry of a virtual horn, the locations of each microphone and measured sound pressure data, pellicular analysis is adopted to recover a set of vibration pattern of the virtual horn. The virtual horn and the recovered vibration information are then incorporated in a full vehicle numerical model to simulate its exterior sound field. The validity of this approach is confirmed by comparing the prediction for a horn in a production vehicle to the corresponding physical test which is required to meet the Brazilian regulation CONTRAN 764/2018.
Yang, Wenlong, MELO, ANDRE
Technical Paper
Experimental Investigation into Modulated Aeroacoustic Cabin Noise arising from Unsteady Flow Conditions2025-01-002905/05/2023
The unsteady wind conditions experienced by a vehicle whilst driving on the road are different to those typically experienced in the steady-flow wind tunnel development environment, due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. This paper presents the use of experimental approach using an SUV-shaped vehicle to assess the effect of unsteady wind on the modulated noise performance, commonly used to evaluate unsteady wind noise characteristics. The approach is extended to assess the pressure distribution on the front side glass of the vehicle, caused by the aerodynamic interactions of the turbulent inflow, to provide insight into the noise generation mechanisms and differences in behaviour between the two environments. The vehicle response to unsteady wind conditions was assessed using two approaches: a dynamic upstream unsteady flow the using active side wind
Jamaluddin, Nur Syafiqah, Oettle, Nicholas, Staron, Domenic
Technical Paper
Tonal noise investigation of automotive HVAC systems : a hybrid method2025-01-002705/05/2023
There is no need to recall how the electrification trend of transport facilities has tightened the requirements around acoustic comfort. Within the automotive industry, these targets are more challenging for Heating, Ventilation and Air Conditioning systems for which passengers are in the foreground of noise emissions. The complexity of the requirements and specifications set by car manufacturers and suppliers stems from a dual aspect. First is quantitative based on the sound pressure level, whether it's the overall level or 1/3 octave band spectra. The second is purely subjective based on the perceived noise quality by stakeholders and final customers worldwide. During development phases, low frequency tone noises are frequently encountered on these systems which might induce discomfort to the passengers. The experimental investigations usually point to an aerodynamic origin, which prompted this research activity. The purpose of this work is to analyze and understand the mechanism of
Bennouna, Saad, Alaoui, Mohamed
Technical Paper
A Methodology to Design the Flow Field of PEM Fuel Cells2023-01-049504/11/2023
Proton Exchange Fuel Cells (PEMFCs) are considered one of the most prominent technologies to decarbonize the transportation sector, with emphasis on long-haul/long-range trucks, off-highway, maritime and railway. The flow field of reactants is dictated by the layout of machined channels in the bipolar plates, and several established designs (e.g., parallel channels, single/multi-pass serpentine) coexist both in research and industry. In this context, the flow behavior at cathode embodies multiple complexities, namely an accurate control of the inlet/outlet humidity for optimal membrane hydration, pressure losses, water removal at high current density, and the limitation of laminar regime. However, a robust methodology is missing to compare and quantify such aspects among the candidate designs, resulting in a variety of configurations in use with no justification of the specific choice. This contrasts with the large operational differences, especially regarding the pressure loss
Corda, Giuseppe, Cucurachi, Antonio, Diana, Martino, Fontanesi, Stefano, D'Adamo, Alessandro
Technical Paper
Ultrathin Pressure Sensor Attaches to SkinTBMG-4649209/01/2022
Researchers have developed an ultrathin pressure sensor that can be attached directly to the skin to measure how fingers interact with objects to produce useful data for medical and technological applications. The sensor has minimal effect on the users’ sensitivity and ability to grip objects and it is resistant to disruption from rubbing.
Magazine Article
An Effective Design of Micro Tesla Valve as a Passive Mixer in Microfluidics Channels 2022-26-117805/26/2022
Mixing fluids is one of the major challenges in microfluidics. Normally, the mixing process is done by diffusion rather than turbulence, which makes it very slow due to low Reynolds number (Re) flow in the range of 0.1 to1. Owing to this behaviour, ineffective mixing occurs when two miscible liquids are mixed purely by diffusion which requires longer striation lengths and therefore longer microfluidic channels along with lengthy mixing time. Homogeneous mixing of solute and solvent is important for providing consistent chemical and biological reactions in µTAS.In this study, we develop a passive mixer that provides efficient mixing using micro tesla valves which allows the flow of liquids in the forward and reverse directions to analyse the formed vortices, turbulent intense areas, Reynolds number, and pressure using Ansys fluent workbench. An optimum design has been arrived by varying the number of cells from 1 to 5 in series and realization is done by excimer laser micromachining.
Singh, Deepak, Sankar PhD, Ravi
Technical Paper
Effect of low viscosity oil and bearings design on oil pressure performance across engine crank train system 2022-01-076703/29/2022
In current market scenario Reliability & Durability of components as became prime focus, with the advent of BS VI emission norm there is tremendous increase in peak firing pressure due to high pressure common rail system and various emission solutions. Crank train system is getting subjected to a never before forces & loading due to emission & performance requirement. For achieving the competitive reliability & durability of main moving parts oil pressure plays a most vital role. In this study the performance optimization of oil pressure has been carried out by experimenting with oil grades & bearing designs. This study comprises of selection of oil & bearing, simulation and finally proto development & verification. Further, the result were compared and best solution recommended.
Gavade, Sujit Vithoba, Gangurde, Prashant, Bhargava, Aashish, Pawar, Satish, Deshmukh, Chandrakant, Mishra, Abhishek
Technical Paper
Ultimate Breakage Load Calculation Method of Cold Gas Inflator Burst Disk2022-01-093803/29/2022
For cold gas Inflator, high refinement of ultimate load forecast is one key of Inflator development. At beginning, two methods based on implicit algorithm, Zero Curvature method and RIKS method were used for burst disk hydro-burst test ultimate pressure load calculation. After considering the effect of bursting disk stamping process, comparing with results of real test, the refinement of the two methods were above 97% both. Studying the corresponding relations between displacement and stress matrix of the center point of burst disk by RISK method. It was found that under ultimate load, the third principal stress vs. displacement curve of the central node shown extreme point, and load step of the point was corresponding the one of maximum pressure load. This shown that after reaching the ultimate load, the center of the bursting disc lost stability in the direction of thickness. Based on the status of stress matrix analysis results of RIKS method, and for solving the nonlinear contact
Shan, Jinhui, Wang, Cheng
Technical Paper
Characterizing shock waves induced by phase change of superheated liquid jets 2022-01-059403/29/2022
The under-expanded nature of flash-boiling spray was considered an important cause of spray collapse via some numerical investigation. However, due to the high optical thickness, the under-expanded nature in flash-boiling jet was difficult to observed by optical diagnosis. The main objective of this study is to prove the existence of under-expanded nature in the gasoline-like fuel (n-hexane) flash-boiling jet under the GDI engine condition, and further reveal the significant influence factors. The experimental examination was carried in a constant volume vessel with ambient pressure ranging from 0.1 bar to 1.0 bar and fuel temperatures from 30℃ to 170℃. In order to capture the flow details in the jet, a high-brightness light source was used in the optical imaging. The shock structure of under-expanded nature was observed in close nozzle region under those conditions above 130℃, and the shock structure was in good agreement with the previous simulation results under the same conditions
Li, Yanfei, Zhang, Jingyu, Ma, Xiao, Shuai, Shijin
Technical Paper
Numerical Investigation on the Internal Flow Field of Electronic Expansion Valve as the Throttle Element2022-01-037803/29/2022
As one of the key components of the heat pump system, the electronic expansion valve mainly plays the role of throttling and reducing pressure in the heat pump system. Firstly, a three-dimensional fluid model is established. The grid is divided and the grid independence is verified. Then, the internal flow field of the electronic expansion valve is numerically simulated based on the fluent software, and the pressure field, velocity field and flow rate changes are analyzed. The flow characteristics of the valve are theoretically analyzed according to the principle of the fluid passing through the orifice. Secondly, the flow characteristics of the valve are simulated, and the theoretical values, CFD simulation results and experimental values are compared to verify the correctness of the established three-dimensional fluid model. Then the influence of geometric parameters such as the diameter and cone angle of the spool on the flow characteristics is studied. The steady-state hydraulic
Liang, Gaoshuai, Li, Liping, Shangguan, Wen-Bin
Technical Paper
Modelling Transient Control of a Turbogenerator on a Drive Cycle2022-01-049503/29/2022
GTDI engines are becoming more efficient, whether individually or part of a HEV (Hybrid Electric Vehicle) powertrain. For the latter, this efficiency manifests itself as increase in zero emissions vehicle mileage. An ideal device for energy recovery is a turbogenerator (TG), and, when placed downstream the conventional turbine it has minimal impact on catalyst light-off and can be used as a bolt-on aftermarket device. A Ricardo WAVE model of a representative GTDI engine was adapted to include a TG (Turbogenerator) and TBV (Turbine Bypass Valve) with the TG in a mechanical turbocompounding configuration, calibrated using steady state mapping data. This was integrated into a co-simulation environment with a SISO (Single-Input, Single-Output) dynamic controller developed in SIMULINK for the actuator control (with BMEP, manifold air pressure and TG pressure ratio as the controlled variables). Transient verification with WAVE-RT was conducted on WLTP and NEDC drive cycles, estimating
Petrovich, Simon, Ebrahimi, Kambiz, Mason, Byron, Watson, Andrew
Technical Paper
METHODOLOGICAL APPROACHES TO CONTROL HC AND CO EMISSIONS DURING COLD CONDITIONS2022-01-054403/29/2022
Diesel Engines are known for its low fuel consumption and at the same time for higher emission formation (NOx, HC, CO and SOOT). Meeting Emission and CO2 targets simultaneously become tough challenge for the Combustion Engineer. HCCI and PCCI combustion concepts allow the reduction of NOx and Soot simultaneously to very low levels with help of Exhaust gas re-circulation (EGR) while maintaining the CO2 emissions advantage of a diesel Engine But due to the low Combustion temperatures, HC and CO will rise drastically, especially when the catalyst bed temperature is not enough to reach light-off temperature to initiate the after-treatment process. This condition will become serve in Lower Engine temperatures (Cold condition) due to the heterogeneous nature of Diesel Combustion and also affects the BSFC of an Engine. At first multiple injection strategies (Pilot quantity and Pilot separation) has been studied to control both HC and CO by increasing the global combustion temperature. In
Mutta, Surendranath
Technical Paper
Evaluation of the Effect of Ambient Conditions on the Fuel Consumption of Commercial Vehicles2022-01-064203/29/2022
The goal of this study was to evaluate the effect of environmental conditions, and particular of ambient temperature, on fuel efficiency. Data from various and extensive operational testing were analyzed, such as tests conducted with four groups of medium and heavy-duty vehicles, involved in regional transport, local transport, pick-up and delivery, and urban transport (school bus). The tests were conducted over 5 months of warm season followed by four months of cold season. Other operational testing was conducted over one year in two different geographic and climatic regions in Canada. Data from extensive track testing conducted based on the SAE J 1321 Fuel Consumption Test Procedure-Type II, with various vehicles in different test condition, from spring to winter, was also analyzed. In this type of tests, a control vehicle is used for the base trial, as well as the final trial. As there is no change on the control vehicle, only the environmental conditions impact the fuel consumption
Surcel, Marius-Dorin
Technical Paper
A Study of Emission Durability and Ash Accumulation of “Advanced Three-Way Catalyst Integrated on Gasoline Particulate Filter” for BS6 (Stage2) Applications2021-26-018209/22/2021
India BS6 Stage2 (2023) regulations demands all Gasoline direct injection (GDI) vehicles to meet particulate number emissions (PN) below 6x10+11# per km. Gasoline particulate filters (GPF) are a proven technology and enable high PN filtration efficiencies throughout the entire vehicle lifetime. One challenge for GPF applications could be the changing emission performance characteristics as a function of mileage due to collected ash and/or soot deposits with implications on back pressure losses and well due to aging of active catalytic components like PGM and Washcoat. The main objective of this technical contribution is to study the above-mentioned challenges while applying Indian driving conditions and typical Indian climate and other ambient conditions. The substrate technology selected for this study is a high porosity GPF designed to enable the integration of a Three-Way functionality into the GPF, commonly described as coated GPF. In this study, the entire Three-Way Catalyst (TWC
Rose, Dominik, Tao, Tinghong, Kataria, Rohit, Boger, Thorsten, Kuehn, Nikolas, Kunert, Susanne, Richter, Joerg Michael, Magar, Avinash
Technical Paper
Coastdown Road Load Coefficients of Passenger Vehicles – Variation Analysis and its Correlation with Temperature2021-26-048709/22/2021
Road Load parameters (rolling resistance & aerodynamic drag) of a vehicle have strong impact on overall Vehicle Emissions & Fuel Economy. The road load coefficients are simulated on chassis dynamometer to carryout emission & fuel economy measurement and are hence required to be found beforehand. A realistic measure of road load parameters can be obtained by conducting a coastdown test. Coastdown test results are hugely impacted by various environmental parameters like ambient temperature, atmospheric pressure, wind speed etc. Though performed in standard boundary conditions, results of multiple tests performed on a vehicle vary from one another due to variations in the mentioned environmental parameters over & above standard test to test variation. This paper aims at studying the variation in test results due to ambient temperature as one of the parameters responsible. For this study, road load coefficients from more than 100 coastdown tests conducted on oval test track for almost 30
Kuhar, Saurabhh, Pattalwar, Ashutosh, Gupta, Parveen
Technical Paper
Misfire Behavior and Mitigations of Passive Pre-chambers at Low-Load Operation in an Optically Accessible Gasoline Engine03-15-03-001609/14/2021
An experiment has been developed to investigate the passive pre-chamber jet ignition process in gasoline engine configurations and low-load operating conditions. The apparatus adopted a modified 4-cylinder 2.0L gasoline engine to enable single-cylinder operation. To reduce the complexity, the piston position was fixed at a predefined position relative to the top dead center (TDC) to simulate thermodynamic conditions at ignition and injection timings. High-speed Infrared (IR) imaging was applied to visualize the jet penetration and ignition process inside the main cylinder and to investigate the cyclic spatial variability. Two passive pre-chambers with different total nozzle areas and numbers of nozzles were used. In addition, the pre-chamber volume and pressure at ignition timing were varied to examine their effect on jet ignition performance. Misfire behavior was observed in the main chamber of all test cases, and the results suggested that the main cause is a high Residual Mass
Lee, Dong Eun, Swanson, Christopher, Yu, Xin, Qiao, Li
Journal Article
Minimum Standard for Portable Gaseous, Oxygen EquipmentAS1046C (Current)08/11/2021
This standard is intended to apply to portable compressed gaseous oxygen equipment. When properly configured, this equipment is used either for the administration of supplemental oxygen, first aid oxygen or smoke protection to one or more occupants of either private or commercial transport aircraft. This standard is applicable to the following types of portable oxygen equipment: a Continuous flow 1 Pre-set 2 Adjustable 3 Automatic b Demand flow 1 Straight-demand 2 Diluter-demand 3 Pressure-demand c Combination continuous flow and demand flow.
A-10 Aircraft Oxygen Equipment Committee
Technical Standard
Spray Behaviors and Gasoline Direct Injection Engine Performance Using Ultrahigh Injection Pressures up to 1500 Bar03-15-01-000707/28/2021
High fuel injection pressure systems for Gasoline Direct Injection (GDI) engines have become widely used in passenger car engines to reduce emissions of particulates and pollutant gases. Current commercial systems operate at pressures of up to 450 bar, but several studies have examined the use of injection pressures above 600 bar, and some have even used pressures around 1500 bar. These works revealed that high injection pressures have numerous benefits including reduced particulate emissions, but there is still a need for more data on the possible benefits of injection pressures above 1000 bar. This article presents spray and engine data from a comprehensive study using several measurement techniques in a spray chamber and optical and metal engines. Shadowgraph imaging and Phase Doppler Interferometry (PDI) were used in a constant volume chamber to interpret spray behavior. Particle Image Velocimetry (PIV) was used to capture near-nozzle air entrainment. Optical engine experiments
Yamaguchi, Akichika, Koopmans, Lucien, Helmantel, Ayolt, Dillner, Johan, Dahlander, Petter
Journal Article
Painless Paper Patch Tests Glucose LevelsTBMG-3834501/01/2021
Researchers have been trying to develop a practical way to use microneedles — tiny needles less than 1 mm in length — for routine at-home medical monitoring. Microneedles are so short that they stay within the skin and do not make contact with any neurons, meaning that they cause no pain. Rather than extracting blood, they draw up fluid in the skin that contains most of the important biomarkers that blood tests look for. Several types of microneedles exist but until now, making a practical device that quickly analyzes the fluid has proved elusive.
Magazine Article
Miniature Electronic Devices Work Under Extreme PressureTBMG-3764809/01/2020
Miniature devices have seamlessly found their way into pressure-sensing and energy-harvesting technologies because of their ability to be frequently stretched, compressed, or twisted. Despite their force-bearing abilities, it is still unclear if repeated physical stress can damage the working of these miniature devices, particularly if there is already a defect in their construction.
Magazine Article
Air Dryer Test ProcedureJ2384_202008 (Current)08/26/2020
This SAE Recommended Practice establishes uniform test procedures for desiccant air dryers used in vehicles with compressed air systems per SAE J2383. Continuous flow desiccant air dryers are excluded from the scope of this document.
Truck and Bus Brake Supply and Control Components Committee
Recommended Practice
Cellulose-Based Sensor Simultaneously Measures Pressure, Temperature, and HumidityTBMG-3748108/01/2020
Researchers have developed a single sensor that combines the ability to measure pressure, temperature, and humidity simultaneously. The sensor has applications such as monitoring patients at home, robotics, electronic skin, functional textiles, surveillance, and security.
Magazine Article
Supersonic Spike DiffuserTBMG-3682405/01/2020
The basic mode of operation for all passive supersonic diffusers is to enable a plume’s inherent power to drive the outer boundary of the exhaust jet to the diffuser wall so that the entire cross-section of the flow has a speed greater than that of sound. This allows mass removal from the area surrounding the nozzle via entrainment. The result is a low-pressure environment similar to the altitude at which the nozzle was designed to operate. Additionally, the nature of supersonic flow prevents pressure interference from the downstream environment.
Magazine Article
Sensitivity Analysis of Aerodynamic Drag Coefficient to EPA Coastdown Ambient Condition Variation2020-01-066604/14/2020
The test cycle average drag coefficient is examined for the variation of allowable EPA coastdown ambient conditions. Coastdown tests are ideally performed with zero wind and at SAE standard conditions. However, often there is some variability in actual ambient weather conditions during testing, and the range of acceptable conditions is further examined in detail as it pertains to the effect on aerodynamic drag derived from the coastdown data. In order to “box” the conditions acceptable during a coastdown test, a sensitivity analysis was performed for wind averaged drag ((CDW ) ̅) as well as test cycle averaged drag coefficients (CDWC) for the fuel economy test cycles. Test cycle average drag for average wind speeds up to 16 km/h and temperatures ranging from 5C to 35C, along with variation of barometric pressure and relative humidity are calculated. The significant effect of ambient cross winds on coastdown determined drag coefficient is demonstrated.
Lounsberry, Todd, Tripp, John, Fadler, Gregory
Technical Paper
Influence of Distributing Channel Configuration and Geometric Parameters on Flow Uniformity in Straight Flow-Field of PEM Fuel Cell2020-01-117304/14/2020
Gas distribution of proton exchange membrane fuel cells (PEMFCs) is mainly decided by flow field of bipolar plate. The improper design of distributing channel, nonuniform gas flow distribution and current density distribution among different straight channels are the leading factors that could tremendously undermine the performance and life expectancy of the cell. However, there is lack of research focusing on distributing channel in straight-parallel flow field. In this work, a three-dimensional numerical model of PEMFC cathode flow field is developed with CFD method to investigate the effects of configuration type and width of the distributing channel on pressure distribution in distributing channel and on reactant flow distribution, pressure drop and concentration distribution in multiple straight channel. Effects of electrochemical reaction and formation of water on the flow distribution are taken into consideration. By extending one group of z-type channels to four groups, a new
Wei, Huili, Chang, Guofeng, Liu, Jinling, Xu, Sichuan
Technical Paper
Volume and Pressure Considerations in Human Body Modeling2019-22-002003/31/2020
The initial presence and dynamic formation of internal voids in human body models have been subjects of discussion within the human body modeling community. The relevant physics of the human body are described and the importance of capturing this physics for modeling of internal organ interactions is demonstrated. Basic modeling concepts are discussed along with a proposal of simulation setups designed to verify model behavior in terms of volume and pressure between internal organs.
Kral, Jiri, de Lima, Anderson
Technical Paper
Spectral Transmission TestJ1796_202003 (Current)03/11/2020
The scope of this SAE performance standard is to define the test method by which the direct solar and visible transmittance of safety glazing materials for road vehicles shall be measured. Adherence to this performance standard will facilitate writing, use, and referencing of reports by government, industry, and other organizations.
Glazing Materials Standards Committee
Technical Standard
Discovery Takes Pressure Off Blood MeasurementsTBMG-3626403/01/2020
Researchers at Monash University are on the verge of creating a revolutionary, portable blood pressure monitoring device that can provide data continuously to patients from the comfort of their home.
Magazine Article
DC Resistivity vs RF Impedance of EMI GasketsAIR1404 (Current)01/30/2020
This AIR discusses the DC resistivity property of EMI gaskets.
AE-4 Electromagnetic Compatibility (EMC) Committee
Information Report
Boss - Plug/Pin, Expansion Type Hole PreparationAIR3276 (Current)08/15/2019
E-25 General Standards for Aerospace and Propulsion Systems
Information Report
Graphene Lid Extends Photoemission Electron Microscopy to LiquidsTBMG-3475307/01/2019
By capping liquids with graphene (an ultrathin sheet of pure carbon), researchers can easily image and analyze liquid interfaces and the surface of nanometer-scale objects immersed in liquids. In the imaging technique known as photoemission electron microscopy (PEEM), ultraviolet light or X-rays bombard a sample, stimulating the material to release electrons from a region at or just beneath its surface. Electric fields act as lenses, focusing the emitted electrons to create an image.
Magazine Article
Pressure Estimation Algorithms in Decoupled Electro-Hydraulic Brake System Considering the Friction and Pressure-Position Relationship2019-01-043804/02/2019
This paper presents several pressure estimation algorithms (PEAs) for a decoupled electro-hydraulic brake system (EHB), which is driven by an electric motor + reduction gear. Most of the pressure control solutions are based on standard pressure-based feedback control, requiring a pressure signal. Although the pressure sensor can produce the pressure feedback signal, it will increase cost and enlarge installation space. The rotation angle of electric motor is available by the built-in sensor, so the pressure can be estimated by using the rotation angle. Considering the typical nonlinearities (i.e. friction, pressure-position relationship) and uncertainties (i.e. disturbance caused by friction model), the estimation-oriented model is established. The LuGre model is selected to describe the friction, and the pressure-position relationship is fitted by a quadratic polynomial. Based on the estimation-oriented model, the force-based PEA (FPEA) and the interconnected PEA (IPEA) are designed
Han, Wei, Xiong, Lu, Yu, Zhuoping
Technical Paper
Vacuum Gauge CalibrationARP7446 (Current)03/06/2019
This SAE Aerospace Recommended Practice (ARP) addresses the general procedure for the best practices for minimizing uncertainty when calibrating thermal conductivity and cold cathode vacuum gauges, which includes the vacuum sensor(s) and accompanying electronics necessary for a pressure measurement to be made. It also includes the best practices for an in-process verification where limitations make it impossible to follow the best practices for minimizing uncertainty. Verifying the accuracy and operation of vacuum gauges is critical to ensure the maintenance of processes while under vacuum.
AMS B Finishes Processes and Fluids Committee
Recommended Practice
Electronic Glove Gives Robotic Hand Sense of TouchTBMG-3372302/01/2019
Stanford engineers have developed an electronic glove containing sensors that could one day give robotic hands the sort of dexterity that humans take for granted.
Magazine Article
UV-Absorption Measurements by Spontaneous Raman Scattering in Low-Sooting Diesel-Like Jets2018-01-504210/11/2018
UV-absorption measurements are sparse in diesel(-like) combustion, particularly close to the premixed burn. Thus, such measurements are conducted in diesel-like jets in a high-pressure vessel in this work, using 1D spontaneous Raman scattering (SRS) from N2. Stokes (~263 nm) and anti-Stokes (~235 nm) SRS induced by a krypton fluoride excimer (KrF*) laser (~248 nm) is exploited. Anti-Stokes SRS can be directly used for attenuation correction of laser-induced fluorescence (LIF) from NO at ~236 nm. Results show the importance of attenuation correction, although the jets are largely non-sooting. To identify absorbers, effects of SRS wavelength, measurement time in the injection event, location in the flame, jet width (JW), temperature, CO concentration, and injection pressure are considered. Particularly strong attenuation observed around the time of second-stage ignition appears to be primarily caused by combustion intermediates such as partially oxidized fuel. In the quasi-steady period
Schulz, Christian, Raffius, Thomas, Ottenwälder, Tamara, Grünefeld, Gerd, Pischinger, Stefan, Koß, Hans-Jürgen
Technical Paper
Measurement Data and Reference Values for Compounds Potentially Found in Aircraft Engine Bleed AirAIR7521 (Current)10/09/2018
This document summarizes published measurement data and reference values for marker chemical compounds listed in ARP4418 (see 2.1.1) potentially found in aircraft engine bleed air.
E-31B Bleed Air Committee
Information Report
FITTING ASSEMBLY, 90° ELBOW, EXTERNAL SWAGE TO FEMALE FLARELESS, HYDRAULICAS6475 (Current)09/19/2018
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Technical Standard
Improving Hole Expansion Ratio by Parameter Adjustment in Abrasive Water Jet Operations for DP80005-11-03-002309/17/2018
The use of Abrasive Water Jet (AWJ) cutting technology can improve the edge stretchability in sheet metal forming. The advances in technology have allowed significant increases in working speeds and pressures, reducing the AWJ operation cost. The main objective of this work was to determine the effect of selected AWJ cutting parameters on the Hole Expansion Ratio (HER) for a DP800 (Dual-Phase) Advanced High-Strength Steel (AHSS) with s0 = 1.2 mm by using a fractional factorial design of experiments for the Hole Expansion Tests (HET). Additionally, the surface roughness and residual stresses were measured on the holes looking for a possible relation between them and the measured HER. A deep drawing quality steel DC06 with s0 = 1.0 mm was used for reference. The fracture occurrence was captured by high-speed cameras and by Acoustic Emissions (AE) in order to compare both methods. Results indicated that using, regardless of the material, a small standoff distance, high water pressure, and
Yilkiran, Deniz, Wölki, Kai, Hübner, Sven, Diaz-Infante, David, Altan, Taylan
Journal Article
Carbon Dioxide Collection and Pressurization TechnologyTBMG-3284309/01/2018
Mars is the ultimate destination for NASA's human exploration program. In Situ Resource Utilization (ISRU) is a key technology required to enable such missions. The goals of using resources available at the exploration site are to reduce launch and delivered mass, reduce risk and cost, enable new missions not possible without ISRU, and expand a human presence in space. A known resource is the Martian atmosphere, composed of 95% CO2, which can be processed to produce useful consumables such as oxygen and methane.
Magazine Article
Passive Flow Control on a Ground-Effect Diffuser Using an Inverted Wing06-11-04-002308/13/2018
In this experimental and computational study a novel application of aerodynamic principles in altering the pressure recovery behavior of an automotive-type ground-effect diffuser was investigated as a means of enhancing downforce. The proposed way of augmenting diffuser downforce production is to induce in its pressure recovery action a second pressure drop and an accompanying pressure rise region close to the diffuser exit. To investigate this concept with a diffuser-equipped bluff body, an inverted wing was situated within the diffuser flow channel, close to the diffuser exit. The wing’s suction surface acts as a passive flow control device by increasing streamwise flow velocity and reducing static pressure near the diffuser exit. Therefore, a second-stage pressure recovery develops along the diffuser’s overall pressure recovery curve as the flow travels from the diffuser’s low pressure, high velocity inlet to its high pressure, low velocity exit. Consequently, downforce production
Ehirim, Obinna, Knowles, Kevin, Saddington,, Alistair, Finnis, Mark
Journal Article
Overpressurization Release DevicesARP1322C (Current)06/21/2018
This SAE Aerospace Recommended Practice (ARP) specifies the minimum design and qualification test recommendations for aircraft wheel overpressurization release devices used with tubeless aircraft tires to protect from possible explosive failure of the contained inflation chamber due to overinflation. Devices of this type provide a means, but not the only means, for showing compliance to Subsection 25.731(d) of Part 25 of Title 14 of the Code of Federal Regulations. Devices of this type will not protect against flash fire explosive conditions within the inflation chamber which may occur due to extremely overheated brakes or spontaneous combustion caused by a foreign substance within the inflation chamber. To help protect against this condition, nitrogen (N2) or other inert gas should be used for inflation.
A-5A Wheels, Brakes and Skid Controls Committee
Recommended Practice
Quick Disconnect for High-Pressure Mate/De-MateTBMG-2905306/01/2018
NASA Kennedy Space Center seeks partners interested in the commercial application of the Quick Disconnect for High Pressure Mate/De-Mate. Designed at KSC, this technology is intended for use in dusty environments where dust particles can contaminate high-pressure connectors, resulting in wear on connector surfaces and unreliable connections. The Quick Disconnect (QD) utilizes the gas supplied by the umbilical to spray on, entrain, and remove dust from the connector surfaces prior to mating.
Magazine Article
High-Speed, High-Resolution Multimode Sensing of Structural Strain and ShapeTBMG-2871104/01/2018
Researchers at NASA's Armstrong Flight Research Center (AFRC) have been developing a fiber optic sensing system (FOSS) that represents a major breakthrough in operational monitoring of myriad structures. FOSS consists of eight 40-foot optical fibers, each containing 2,000 fiber Bragg grating (FBG) sensors along its entire length. These fibers are attached to the surface of, or even embedded within a structure. As the structure experiences stress or pressure, the FBG sensors respond to the strain. FOSS uses this response to calculate a variety of critical parameters, including strain, shape deformation, temperature, liquid level, strength, and operational loads.
Magazine Article
Malleable ‘Electronic Skin’ Self-Healable, RecyclableTBMG-2874804/01/2018
CU Boulder researchers have developed a new type of malleable, self-healing and fully recyclable “electronic skin” that has applications ranging from robotics and prosthetic development to better biomedical devices.
Magazine Article
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