This SAE Recommended Practice sets forth a method for evaluating the flow properties of automotive sealers that have been dispensed via a high pressure automatic system.

Materials, Processes and Parts Council

Low-Order Prediction of Mineral Dust Sticking Probability in Turboshaft Engines

F-0076-2020-16338

10/5/2020

ABSTRACT Rotorcraft operations in arid environments can result in the ingestion of large quantities of dust particles into turboshaft engines, where they can melt and deposit on high pressure turbine nozzle guide vanes. This can result in reduced engine life-span and in worst case scenarios, in-flight engine failure. Predicting the extent and rate at which this damage occurs has proven difficult owing to the wide range of variables relating to the dust cloud, engine and most importantly, the properties of the particulate encountered. Whilst significant work has been carried out to model the particle deposition process for both volcanic ash and coal fly-ash, there is scarce similar work for the different types of mineral dusts rotorcraft encounter. In this contribution, we assess the suitability of two opposing numerical approaches for use in a generalised, reduced-order deposition model of individual mineral particles depositing on a vane. Both models are seen to be heavily reliant

Ellis, Matthew, Bojdo, Nicholas, Filippone, Antonio, Jones, Merren, Pawley, Alison

Effect of Initial Fuel Temperature on Spray Characteristics of Multicomponent Fuel

2020-01-21139/15/2020

Fuel design concept has been proposed for low emission and combustion control in engine systems. In this concept, the multicomponent fuels, which are mixed with a high volatility fuel (gasoline or gaseous fuel components) and a low volatility fuel (gas oil or fuel oil components), are used for artificial control of fuel properties. In addition, these multicomponent fuels can easily lead to flash boiling which promote atomization and vaporization in the spray process. In order to understand atomization and vaporization process of multicomponent fuels in detail, the model for flash boiling spray of multicomponent fuel have been constructed and implemented into KIVA3V rel.2. This model considers the detailed physical properties and evaporation process of multicomponent fuel and the bubble nucleation, growth and disruption in a nozzle orifice and injected fuel droplets. In this study, the results from numerical simulation using this model were compared with experimental data (liquid and

Kawano, Daisuke, Tsukiji, Kentaro, Saito, Hiroki, Matsuda, Dai, Matsumura, Eriko, Senda, Jiro

Influence of Nozzle Geometry Parameters on the Propagation of Fuel Spray Investigated with Linear and Non-Linear Regression Models

2020-01-21149/15/2020

The nozzle geometry of fuel injectors has a strong influence on turbulences and pressure gradients within the nozzle flow. The flow situation at the nozzle outlet determines the spray propagation into the ambient atmosphere. This spray penetration is critical for gasoline direct injection (GDI) systems. When the spray penetration is too high, it can cause wall and cylinder impingement, which increases particle emissions drastically. However, prediction of fuel spray propagation in dependency of nozzle hole geometry is difficult due to the large difference in scale between the nozzle flow and the spray development. Because of this, spray measurements with varying nozzle geometry parameters and statistical evaluation of these datasets are useful for the future development of fuel injectors. In this study, shadowgraphy measurements of real-size single-hole glass nozzles are presented. The nozzles cover a wide range of geometry parameters relevant to a GDI system. The total penetration

Conrad, Chris, Wensing, Michael

Numerical Simulations of the Effect of Cold Fuel Temperature on In-Nozzle Flow and Cavitation Using a Model Injector Geometry

2020-01-21169/15/2020

In the present study, Large Eddy Simulations (LES) have been performed with a 3D model of a step nozzle injector, using n-pentane as the injected fluid, a representative of the high-volatility components in gasoline. The influence of fuel temperature and injection pressure were investigated in conditions that shed light on engine cold-start, a phenomenon prevalent in a number of combustion applications, albeit not extensively studied. The test cases provide an impression of the in-nozzle phase change and the near-nozzle spray structure across different cavitation regimes. Results for the 20oC fuel temperature case (supercavitating regime) depict the formation of a continuous cavitation region that extends to the nozzle outlet. Collapse-induced pressure wave dynamics near the outlet cause a transient entrainment of air from the discharge chamber towards the nozzle. The extent of air entrainment appears noticeably reduced on the simulations with colder fuel (−10oC, incipient cavitation

Bontitsopoulos, Stavros, Hamzehloo, Arash, Aleiferis, Pavlos, Cracknell, Roger

High-Speed Imaging Study on the Effects of Internal Geometry on High-Pressure Gasoline Sprays

2020-01-21119/15/2020

High-pressure gasoline injection can improve combustion efficiency and lower engine-out emissions; however, the spray characteristics of high-pressure gasoline (>500 bar) are not well known. Effects of different injector nozzle geometry on high-pressure gasoline sprays were studied using a constant volume chamber. Five nozzles with controlled internal flow features including differences in nozzle inlet rounding, conicity, and outlet diameter were investigated. Reference grade gasoline was injected at fuel pressures of 300, 600, 900, 1200, and 1500 bar. The chamber pressure was varied using nitrogen at ambient temperature and pressures of 1, 5, 10, and 20 bar. Spray development was recorded using diffuse backlit shadowgraph imaging methods. The results extracted to describe the spray development included spray tip penetration distance, spray tip penetration rate, and spray angle and include comparisons of the effects of operating conditions and injector geometry variants on spray

Medina, Mario, Zhou, Yichen, Fatouraie, Mohammad, Wooldridge, Margaret

High-Speed Imaging of Main-Chamber Combustion of a Narrow Throat Pre-Chamber under Lean Conditions

2020-01-20819/15/2020

Pre-chamber combustion (PCC) allows an extension on the lean limit of an internal combustion engine (ICE). This combustion mode provides lower NOx emissions and shorter combustion durations that lead to a higher indicated efficiency. In the present work, a narrow throat pre-chamber was tested, which has a unique nozzle area distribution in two rows of six nozzle holes each. Tests were carried out in a modified heavy-duty engine for optical visualization. Methane was used as fuel for both the pre-chamber and the main chamber. Seven operating points were tested, including passive pre-chamber mode as a limit condition, to study the effect of pre- and main-chamber fuel addition on the pre-chamber jets and the main chamber combustion via chemiluminescence imaging. A typical cycle of one of the tested conditions is explained through the captured images. Observations of the typical cycle reveal a predominant presence of only six jets (from the lower row), with well-defined jet structures. A

Echeverri Marquez, Manuel, Hlaing, Ponnya, Tang, Qinglong, Sampath, Ramgopal, Cenker, Emre, Ben Houidi, Moez, Magnotti, Gaetano, Johansson, Bengt

Simultaneous Negative PLIF and OH* Chemiluminescence Imaging of the Gas Exchange and Flame Jet from a Narrow Throat Pre-Chamber

2020-01-20809/15/2020

Pre-chamber combustion (PCC) is a promising engine combustion concept capable of extending the lean limit at part load. The engine experiments in the literature showed that the PCC could achieve higher engine thermal efficiency and much lower NOx emission than the spark-ignition engine. Improved understanding of the detailed flow and combustion physics of PCC is important for optimizing the PCC combustion. In this study, we investigated the gas exchange and flame jet from a narrow throat pre-chamber (PC) by only fueling the PC with methane in an optical engine. Simultaneous negative acetone planar laser-induced fluorescence (PLIF) imaging and OH* chemiluminescence imaging were applied to visualize the PC jet and flame jet from the PC, respectively. Results indicate a delay of the PC gas exchange relative to the built-up of the pressure difference (△ P) between PC and the main chamber (MC). This should be due to the gas inertia inside the PC and the resistance of the PC nozzle. The PC

Tang, Qinglong, Sampath, Ramgopal, Echeverri Marquez, Manuel, Hlaing, Ponnya, Sharma, Priybrat, Ben Houidi, Moez, Cenker, Emre, Chang, Junseok, Magnotti, Gaetano, Johansson, Bengt

Investigation on Effect of Offset Orifice Nozzle on Diesel Combustion Characteristics

2020-01-20389/15/2020

Compression ignition engines provide superior thermal efficiency over other internal combustion engines. Unfortunately the combustion process is diffusive combustion, meaning a lot of fuel is impinged the on the piston and cylinder wall. This creates cooling loss coupled with smoke, CO and THC. Minimization of the nozzle orifice diameter is a simple method widely used to shorten spray penetration. However, decreasing the nozzle orifice diameter also decreases fuel flow rate resulting in a prolonged injection and combustion process and reducing thermal efficiency. An offset orifice nozzle causes less fuel impingement by shorter fuel spray penetration without significant reduction of fuel flow rate. The offset orifice nozzle was made by shifting its alignment from the center of the sac to the edge of the sac following the swirl direction. A counterbore design was applied to maintain constant orifice length. This paper investigates the effects of nozzle orifice position on combustion

Ewphun, Pop-Paul, Nagasawa, Tsuyoshi, Kosaka, Hidenori, Sato, Susumu

Supersonic Spike Diffuser

TBMG-368245/1/2020

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.

Multimaterial Fiber “Ink” for 3D-Printed Devices

TBMG-359752/1/2020

A new method uses standard 3D printers to produce functioning devices with the electronics already embedded inside. The devices are made of fibers containing multiple interconnected materials that can light up, sense their surroundings, store energy, or perform other actions.

Self-Assembled Micro-Organogels Enable 3D Printing of Silicone Structures

TBMG-347527/1/2019

For the millions of people every year who have or need medical devices implanted, an advancement in 3D printing technology could enable significantly quicker implantation of devices that are stronger, less expensive, more flexible, and more comfortable than anything currently available. Such devices are molded, which could take days or weeks to create customized parts designed to fit an individual patient. The 3D printing method cuts that time to hours; additionally, small and complex devices such as pressure-sensitive valves, simply cannot be molded in one step.

High Strength Elevated Temperature Bolting Practice

ARP700C (Current)5/3/2019

This SAE Aerospace Recommended Practice (ARP) provides general information on the design and installation of threaded fasteners in high strength and high temperature applications in propulsion systems. Some of the more common definitions of fastener terminology are also provided.

E-25 General Standards for Aerospace and Propulsion Systems

Dispenser Nozzle Spouts for Liquid Fuels Intended for Use with Spark Ignition and Compression Ignition Engines

J285_201904 (Current)4/29/2019

Fuel Systems Standards Committee

Printing Technology Uses Sound Waves to Control Size of Liquid Droplets

TBMG-337022/1/2019

Liquid droplets are used in many applications, from printing ink on paper to creating microcapsules for drug delivery. Inkjet printing is the most common technique used to pattern liquid droplets, but it's only suitable for liquids that are roughly ten times more viscous than water. Many fluids of interest to researchers are far more viscous; for example, biopolymer and cell-laden solutions that are vital for biopharmaceuticals and bioprinting are at least 100 times more viscous than water. Some sugar-based biopolymers could be as viscous as honey, which is 25,000 times more viscous than water. The viscosity of these fluids also changes dramatically with temperature and composition, making it more difficult to optimize printing parameters to control droplet sizes.

Valve Flow Coefficients under Engine Operation Conditions: Pressure Ratios, Pressure and Temperature Levels

2019-01-00411/15/2019

Engine valve flow coefficients are not only used to characterize the performance of valve/port designs, but also for modelling gas exchange in 0D/1D engine simulation. Flow coefficients are usually estimated with small pressure ratios and at ambient air conditions. In contrast, the ranges for pressure ratio, pressure and temperature level during engine operation are much more extensive. In this work the influences of these three parameters on SI engine poppet valve flow coefficients are investigated using 3D CFD and measurements for validation. While former investigations already showed some pressure ratio dependencies by measurement, here the use of 3D CFD allows a more comprehensive analysis and a deeper understanding of the relevant effects. At first, typical ranges for the three mentioned parameters during engine operation are presented. A preliminary study for a simple nozzle geometry shows the suitability of the utilized 3D CFD code for partially overcritical flow, and

Fasse, Sven, Grill, Michael, Bargende, Michael

Visual Analyses of End of Injection Liquid Structures and the Behaviour of Nozzle Surface-Bound Fuel in a Direct Injection Diesel Engine

2019-01-00591/15/2019

For efficiency, the majority of modern diesel engines implement multiple injection strategies, increasing the frequency of transient injection phases and thus, end of injection (EOI) events. Recent advances in diagnostic techniques have identified several EOI phenomena pertinent to nozzle surface wetting as a precursor for deposit formation and a potential contributor towards pollutant emissions. To investigate the underlying processes, highspeed optical measurements at the microscopic scale were performed inside a motored diesel engine under low load/idling conditions. Visualisation of the injector nozzle surface and near nozzle region permitted an indepth analysis of the post-injection phenomena and the behaviour of fuel films on the nozzle surface when the engine is not fired. Inspection of the high-speed video data enabled an interpretation of the fluid dynamics leading to surface wetting, elucidating the mechanisms of deposition and spreading. As the needle re-seated, the abrupt

Sykes, Dan, de Sercey, Guillaume, Gold, Martin, Pearson, Richard, Crua, Cyril

Spray Characterization of Gasoline Direct Injection Sprays Under Fuel Injection Pressures up to 150 MPa with Different Nozzle Geometries

2019-01-00631/15/2019

Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures. This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors’ flow characteristics. Spray imaging was performed using a

Yamaguchi, Akichika, Koopmans, Lucien, Helmantel, Arjan, Karrholm, Fabian Peng, Dahlander, Petter

Evaluation of Diesel Spray with Non-Circular Nozzle - Part I: Inert Spray

2019-01-00651/15/2019

Numerous studies have characterized the impact of high injection pressure and small nozzle holes on spray quality and the subsequent impact on combustion. Higher injection pressure or smaller nozzle diameter usually reduce soot emissions owing to better atomization quality and fuel-air mixing enhancement. The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. An alternate approach impacting spray quality is investigated in this paper, specifically the impact of non-circular nozzles. The concept was explored experimentally in an optically accessible constant-volume combustion chamber (CVCC). Non-reacting spray evaluations were conducted at various ambient densities (14.8, 22.8, 30 kg/m3) under inert gas of Nitrogen (N2) while injection pressure was kept at 100 MPa. Shadowgraph imaging was used to obtain macroscopic spray characteristics such as spray structure, spray penetration, and the spray cone angle. Analysis from

Cung, Khanh, Moiz, Ahmed Abdul, Shah, Bansal, Kalaskar, Vickey, Miwa, Jason, Abidin, Zainal

The Nozzle Flows and Atomization Characteristics of the Two-Component Surrogate Fuel of Diesel from Indirect Coal Liquefaction at Engine Conditions

2018-01-16919/10/2018

Recently, all world countries facing the stringent emission regulations have been encouraged to explore the clean fuel. The diesel from indirect coal liquefaction (DICL) has been verified that can reduce the soot and NOx emissions of compression-ignition engine. However, the atomization characteristics of DICL are rarely studied. The aim of this work is to numerically analyze the inner nozzle flow and the atomization characteristics of the DICL and compare the global and local flow characteristics of the DICL with the NO.2 diesel (D2) at engine conditions. A surrogate fuel of the DICL (a mixture of 72.4% n-dodecane and 27.6% methylcyclohexane by mass) was built according to its components to simulate the atomization characteristics of the DICL under the high-temperature and high-pressure environment (non-reacting) by the Large Eddy Simulation (LES). The simulation results show that the DICL is more likely to form cavitation compared with D2, and the turbulence level at the orifice exit

Huang, Zhong, Zhang, Wenzheng, Xia, Jin, Ju, Dehao, Han, Dong, Lu, Xing-Cai

Characterizing Spray Propagation of GDI Injectors under Crossflow Conditions

2018-01-16969/10/2018

In DISI engines spray distribution and atomization directly influence mixture formation, the quality of combustion and the resulting emissions. Constant Volume Chambers (CVC) are commonly used to characterize sprays of gasoline injectors. The CVCs provide good optical access but the flow condition of the engine cannot be reproduced. Optically accessible engines in contrast deliver realistic flow conditions but have restricted optical access. In former investigations we compared the spray propagation of different injectors in constant volume chambers and in optical accessible engines. These results showed a clear difference of the spray propagation in the CVC and the engine, especially at high charge motion conditions in the engine. To find an appropriate way to investigate the impact of different charge motion a flow channel was built with adjustable crossflow velocities from 5-50 m/s. The spray propagation during the injection process was measured with high-speed shadowgraphy. Two

Welss, Richard, Bornschlegel, Sebastian, Wensing, Michael

An Experimental Investigation on Spray Mixing and Combustion Characteristics for Spray C/D Nozzles in a Constant Pressure Vessel

2018-01-17839/10/2018

The Engine Combustion Network (ECN) is a coordinate effort from research partners from all over the world which aims at creating a large experimental database to validate CFD calculations. Two injectors from ECN, namely Spray C and D, have been compared in a constant pressure flow vessel, which enables a field of view of more than 100 mm. Both nozzles have been designed with similar flow metrics, with Spray D having a convergent hole shape and Spray C a cylindrical one, the latter being therefore more prone to cavitation. Although the focus of the study is on reacting conditions, some inert cases have also been measured. High speed schlieren imaging, OH* chemiluminescence visualization and head-on broadband luminosity have been used as combustion diagnostics to evaluate ignition delay, lift off length and reacting tip penetration. Parametric variations include ambient temperature, oxygen content and injection pressure variations. Results extend the range of variation of previously

Pastor, Jose V., Garcia-Oliver, Jose M, Garcia, Antonio, Morales López, Andrés

Outwardly Opening Hollow-Cone Diesel Spray Characterization under Different Ambient Conditions

2018-01-16949/10/2018

The combustion quality in modern diesel engines depends strictly on the quality of the air-fuel mixing and, in turn, from the quality of spray atomization process. So air-fuel mixing is strongly influenced by the injection pressure, geometry of the nozzle duct and the hydraulic characteristics of the injector. In this context, spray concepts alternative to the conventional multi-hole nozzles could be considered as solutions to the extremely high injection pressure increase to assure a higher and faster fuel-air mixing in the piston bowl, with the final target of increasing the fuel efficiency and reducing the engine emissions. The study concerns an experimental depiction of a spray generated through a prototype high-pressure hollow-cone nozzle, under evaporative and non-evaporative conditions, injecting the fuel in a constant-volume combustion vessel controlled in pressure and temperature up to engine-like gas densities in order to measure the spatial and temporal fuel patterns. The

Montanaro, Alessandro, Allocca, Luigi, Beatrice, Carlo, Ianniello, Roberto

Assessment of the New Features of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector by Means of Engine Performance Characterization and Spray Visualization

2018-01-16979/10/2018

The application of more efficient compression ignition combustion concepts requires advancement in terms of fuel injection technologies. The injector nozzle is the most critical component of the whole injection system for its impact on the combustion process. It is characterized by the number of holes, diameter, internal shape, and opening angle. The reduction of the nozzle hole diameter seems the simplest way to promote the atomization process but the number of holes must be increased to keep constant the injected fuel mass. This logic has been applied to the development of a new generation of injectors. First, the tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate. The vertical movement of the needle generates an annulus area for the fuel delivery on 360 degrees, so controlling the atomization as a function of the vertical plate position. Second, on the base of the obtained results, the authors have

Sequino, Luigi, Belgiorno, Giacomo, Di Blasio, Gabriele, Mancaruso, Ezio, Beatrice, Carlo, Vaglieco, Bianca Maria

Spray Parameters of Fuel Blends of Recycled Lubricating Oil and Diesel

2018-01-16939/10/2018

The use of alternative fuels consisting of mineral and synthetic waste substances such as recycled lubricating oil blended with diesel is a measure to mitigate the environmental impact of the fossil fuels. However, to inject these fuel blends into contemporary engines without changes to their components, it must maintain or improve the fuel injection characteristics compared to neat diesel, in order to maintain or improve the engine performance. In the present research, the spray parameters of injected fuel, such as length, angle and atomization particle diameter in terms of the Sauter mean diameter (SMD), are modeled depending on the characterization of different concentration of the recycled lubricating oil blended with diesel. It was found that the same nozzle geometry of the injectors can provide an equivalent fuel spray performance for different concentrations of these alternative fuel blends, and that the increase of the recycled lubricating oil in the fuel blend reduced the wear

Gutierrez, Marcos, Castillo, Andres, Iniguez, Juan, Reyes, Gorky

High Strength Elevated Temperature Bolting Practice

ARP700B (Historical)8/23/2018

E-25 General Standards for Aerospace and Propulsion Systems

Application of Vortex Control to an Automotive Transcritical R744 Ejector Cycle

2018-01-00604/3/2018

Expansion work recovery by two-phase ejector is known to be beneficial to vapor compression cycle performance. However, one of the biggest challenges with ejector vapor compression cycles is that the ejector cycle performance is sensitive to working condition changes which are common in automotive applications. Different working conditions require different ejector geometries to achieve maximum performance. Slightly different geometries may result in substantially different COPs under the same conditions. The ejector motive nozzle throat diameter (motive nozzle restrictiveness) is one of the key parameters that can significantly affect ejector cycle COP. This paper presents the experimental results of the application of a new two-phase nozzle restrictiveness control mechanism to an automotive transcritical R744 ejector cycle. This new control mechanism, vortex control, utilizes an adjustable vortex at the nozzle inlet to control the nozzle restrictiveness on the two-phase flow without

Zhu, Jingwei, Elbel, Stefan

Experimental Analysis of Fuel and Injector Body Temperature Effect on the Hydraulic Behavior of Latest Generation Common Rail Injection Systems

2018-01-02824/3/2018

The present paper describes the effect of thermal conditions on the hydraulic behavior of Diesel common rail injectors, with a particular focus on low temperatures for fuel and injector body. The actual injection system thermal state can significantly influence both the injected quantity and the injection shape, requiring proper amendments to the base engine calibration in order to preserve the combustion efficiency and pollutant emissions levels. In particular, the introduction of the RDE (Real Driving Emission) test cycle widens the effective ambient temperature range for the homologation cycle, this way stressing the importance of the thermal effects analysis. An experimental test bench was developed in order to characterize the injector in an engine-like configuration, i.e. fuel pump, piping, common rail, pressure control system and injectors. One of the injectors is used for the measurement of injection rate time profile by means of a Zeuch method-based injection analyzer, mean

Cavicchi, Andrea, Postrioti, Lucio, Pesce, Francesco Concetto, Ferrara, Umberto

Methodology and Tools to Predict GDI Injector Tip Wetting as Predecessor of Tip Sooting

2018-01-02864/3/2018

With upcoming emission regulations particle emissions for GDI engines are challenging engine and injector developers. Despite the introduction of GPFs, engine-out emission should be optimized to avoid extra cost and exhaust backpressure. Engine tests with a state of the art Miller GDI engine showed up to 200% increased particle emissions over the test duration due to injector deposit related diffusion flames. No spray altering deposits have been found inside the injector nozzle. To optimize this tip sooting behavior a tool chain is presented which involves injector multiphase simulations, a spray simulation coupled with a wallfilm model and testing. First the flow inside the injector is analyzed based on a 3D-XRay model. The next step is a Lagrangian spray simulation coupled with a wallfilm module which is used to simulate the fuel impingement on the injector tip and counter-bores. Lower injection pressures and a rounded edge at the nozzle inlet due to hydro-erosive grinding are

Fischer, Armin, Thelliez, Marina

Oil Circulation Rate in Ejector Cooling Cycles

2018-01-00774/3/2018

In this study, the influence of compressor speed, ejector motive nozzle needle position and evaporator inlet metering valve opening on the oil circulation rates (OCRs) of an automotive R744 transcritical standard ejector cycle was experimentally investigated. Significantly higher OCR (~10%) was observed at the evaporator inlet of the ejector cycle than at the high pressure side. It has been observed that evaporator OCR was increased with increasing compressor speed. When the motive nozzle needle moved towards the nozzle throat, both compressor discharge flow rate and evaporator OCR were observed to be significantly lowered. As the evaporator inlet metering valve opening was adjusted, the compressor mass flow rate did not vary significantly while the evaporator mass flow rate decreased with decreasing metering valve opening. The evaporator OCR decreased from 6.5% to 2.2% as the metering valve opening varied from 86% to 27%.

Zhu, Jingwei, Botticella, Francesco, Elbel, Stefan

Modeling the Dynamic Coupling of Internal Nozzle Flow and Spray Formation for Gasoline Direct Injection Applications

2018-01-03144/3/2018

A numerical study has been carried out to assess the effects of needle movement and internal nozzle flow on spray formation for a multi-hole Gasoline Direct Injection system. The coupling of nozzle flow and spray formation is dynamic in nature and simulations with pragmatic choice of spatial and temporal resolutions are needed to analyze the sprays in a GDI system. The dynamic coupling of nozzle flow and spray formation will be performed using an Eulerian-Lagrangian Spray Atomization (ELSA) approach. In this approach, the liquid fuel will remain in the Eulerian framework while exiting the nozzle, while, depending on local instantaneous liquid concentration in a given cell and amount of liquid in the neighboring cells, part of the liquid mass will be transferred to the Lagrangian framework in the form of Lagrangian parcels. Such approach requires solving an additional transport equation apart from the conservation equations of mass, momentum, species, energy, and turbulence in Eulerian

Saha, Kaushik, Srivastava, Priyesh, Quan, Shaoping, Senecal, P. K., Pomraning, Eric, Som, Sibendu

Contrary Effects of Nozzle Length on Spray Primary Breakup under Subcooled and Superheated Conditions

2018-01-03024/3/2018

Nozzle length has been proven influencing fuel spray characteristics, and subsequently fuel-air mixing and combustion processes. However, almost all existing related studies are conducted when fuel is subcooled, of which fuel evaporation is extremely weak, especially at the near nozzle region. In addition, injector tip can be heated to very high temperature in SIDI engines, which would trigger flash boiling fuel spray. Therefore, in this study, effect of nozzle length on spray characteristics is investigated under superheated conditions. Three single-hole injectors with different nozzle length were studied. High speed backlit imaging technique was applied to acquire magnified near nozzle spray images based on an optical accessible constant volume chamber. Fuel pressure was maintained at 15 MPa, and n-hexane was chosen as test fuel. Fuel temperature ranged from 25 °C to 85 °C, and ambient pressure ranged from 20 kPa to 200 kPa, which provided a wide range of subcooled and superheated

Wu, Shengqi, Xu, Min, Yang, Shangze, Yin, Peng

Effect of Micro-Hole Nozzle on Diesel Spray and Combustion

2018-01-03014/3/2018

The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. One area of promise, injector nozzles with micro-holes (i.e. down to 30 μm), still need further investigation. Reduction of nozzle orifice diameter and increased fuel injection pressure typically promotes air entrainment near-nozzle during start of injection. This leads to better premixing and consequently leaner combustion, hence lowering the formation of soot. Advances in numerical simulation have made it possible to study the effect of different nozzle diameters on the spray and combustion in great detail. In this study, a baseline model was developed for investigating the spray and combustion of diesel fuel at the Spray A condition (nozzle diameter of 90 μm) from the Engine Combustion Network (ECN) community. Upon validation of parameters such as spray penetration, lift-off length, and ignition delay the baseline simulation was extended to study different nozzle

Cung, Khanh, Bitsis, Daniel Christopher, Briggs, Thomas, Kalaskar, Vickey, Abidin, Zainal, Shah, Bansal, Miwa, Jason

LES Investigation of ECN Spray G2 with an Eulerian Stochastic Field Cavitation Model

2018-01-02914/3/2018

Due to an ongoing trend of high injection pressures in the realm of internal combustion engines, the role of cavitation that typically happens inside the injector nozzle has become increasingly important. In this work, a large Eddy Simulation (LES) with cavitation modeled on the basis of an Eulerian Stochastic Field (ESF) method and a homogeneous mixture model is performed to investigate the role of cavitation on the Engine Combustion Network (ECN) spray G2. The Eulerian stochastic field cavitation model is coupled to a pressure based solver for the flow, which lowers the computational cost, thereby making the methodology highly applicable to realistic injector geometries. Moreover, the nature of the Eulerian stochastic field method makes it more convenient to achieve a high scalability when applied to parallel cases, which gives the method the edge over cavitation models that are based on Lagrangian tracking. The result of the Eulerian stochastic field simulation is compared against

Chen, Boxiong, Oevermann, Michael

Evaluation of Shot-to-Shot In-Nozzle Flow Variations in a Heavy-Duty Diesel Injector Using Real Nozzle Geometry

2018-01-03034/3/2018

Cyclic variability in internal combustion engines (ICEs) arises from multiple concurrent sources, many of which remain to be fully understood and controlled. This variability can, in turn, affect the behavior of the engine resulting in undesirable deviations from the expected operating conditions and performance. Shot-to-shot variation during the fuel injection process is strongly suspected of being a source of cyclic variability. This study focuses on the shot-to-shot variability of injector needle motion and its influence on the internal nozzle flow behavior using diesel fuel. High-speed x-ray imaging techniques have been used to extract high-resolution injector geometry images of the sac, orifices, and needle tip that allowed the true dynamics of the needle motion to emerge. These measurements showed high repeatability in the needle lift profile across multiple injection events, while the needle radial displacement was characterized by a much higher degree of randomness. A robust

Torelli, Roberto, Matusik, Katarzyna E., Nelli, Kyle C., Kastengren, Alan L., Fezzaa, Kamel, Powell, Christopher F., Som, Sibendu, Pei, Yuanjiang, Tzanetakis, Tom, Zhang, Yu, Traver, Michael, Cleary, David J.

Experimental and Computational Investigation of Subcritical Near-Nozzle Spray Structure and Primary Atomization in the Engine Combustion Network Spray D

2018-01-02774/3/2018

In order to improve understanding of the primary atomization process for diesel-like sprays, a collaborative experimental and computational study was focused on the near-nozzle spray structure for the Engine Combustion Network (ECN) Spray D single-hole injector. These results were presented at the 5th Workshop of the ECN in Detroit, Michigan. Application of x-ray diagnostics to the Spray D standard cold condition enabled quantification of distributions of mass, phase interfacial area, and droplet size in the near-nozzle region from 0.1 to 14 mm from the nozzle exit. Using these data, several modeling frameworks, from Lagrangian-Eulerian to Eulerian-Eulerian and from Reynolds-Averaged Navier-Stokes (RANS) to Direct Numerical Simulation (DNS), were assessed in their ability to capture and explain experimentally observed spray details. Due to its computational efficiency, the Lagrangian-Eulerian approach was able to provide spray predictions across a broad range of conditions. In general

Battistoni, Michele, Magnotti, Gina M., Genzale, Caroline L., Arienti, Marco, Matusik, Katarzyna E., Duke, Daniel J., Giraldo, Jhoan, Ilavsky, Jan, Kastengren, Alan L., Powell, Christopher F., Marti-Aldaravi, Pedro

Optimal Injection Strategies to Compensate for Injector Aging in Common Rail Fuel Systems

2018-01-11604/3/2018

Aging effects such as coking or erosive damage that occur in fuel injection nozzles are known to deteriorate the engine performance. This article proposes an optimization method to compensate for injector aging and to control the combustion behavior over engine lifetime by adapting the injection strategy. First, a control-oriented combustion model is presented, which takes the condition of the injection nozzle into account. In combination with a simulation model of the entire fuel injection system from a previous study, the model is capable of predicting the heat release rate (HRR) at different working conditions. Measurements with a single-cylinder diesel engine were performed, using injectors with modified and aged nozzles, to validate the proposed combustion model and particularly to analyze the influence of injector aging. Using the simulation model, optimal injection strategies were obtained by applying a line search optimization scheme to recover a reference HRR trajectory

Hofmann, Oliver, Schuckert, Sebastian, Wachtmeister, Georg, Rixen, Daniel

Single-Hole Asymmetric GDI Injector: Influence of the Drill Angle and the Counter-Bore under Flash-Boiling and Non-Flash-Boiling Conditions

2018-01-02884/3/2018

Sac-type nozzles, which are often used in gasoline direct injection (DI), induce asymmetry to the spray. The drill angle, that is, the angle between the axis of the nozzle and the axis of the injector, is one of the key causes of the asymmetric flow. Despite its significance, the influence of the drill angle on spray is poorly understood. In the current work, a parametric study has been carried out using single-hole sac-type nozzles by varying the drill angle. The drill angle was varied from a value of 0° to 45° in steps of 15°. Apart from the geometric variation, the ambient pressure and the fuel temperature were varied to achieve flash-boiling and non-flash-boiling spray conditions. Simulations were carried out using an in-house computational fluid dynamics (CFD) solver that accounts for thermodynamic non-equilibrium coupled with a liquid-gas interface-area-density transport model to account for primary atomization of the fuel. The spray angle was calculated on the basis of a

Rachakonda, Sampath K., Paydarfar, Arman, Schmidt, David

Fluid Structure Interaction Analysis of Acrylic Optically Transmissive Nozzles

2017-01-230910/8/2017

In this paper, a contrast experiment has been carried out for discussing the phenomenon of fuel dripping at the end of injection by using the different nozzles with varied materials. The experiment results show that the nozzle deformation has an important effect on the fuel dripping at the end of injection. The duration of the fuel shut-off process with the steel nozzle which producing smaller deformation is shorter than the polymethyl methacrylate nozzle. The mass of fuel dripping with the steel nozzle is less. For implementing a deep analysis on the experimental phenomenon about the fuel dripping with the polymethyl methacrylate nozzle, a three dimensional numerical simulation research was carried out for analyzing the influence of fuel flow inside nozzle on the solid deformation and stress distribution of the nozzle by using Fluid-Structure-Interaction method. The simulation results show that the deformation and the stress are mainly occurred in the sac and the inlet of the orifice

Wen, Hua, Liang, Shuaishuai, Chen, Peng, Jiang, Guangjun

Effects of the Residual/Sucked Air Bubbles on Diesel Near - Nozzle Spray Structure

2017-01-231410/8/2017

Study of the spray formation in vicinity of the nozzle is essential to better understand and predict the physical processes involved in the diesel atomization. The initial spray patterns were found to be different from one injection to another during our visualization experiments, which was carried out based on a long distance microscope with a high speed camera in this work. It was found that the initial spray might contain a clear single mushroom, tail region and intact liquid column, or have a tail in front of the mushroom without changing its direction. Occasionally, it presented as a double-mushroom shape, or did not include a clear mushroom. Our visualization results showed that the various spray structures were observed at different injection pressures and different injection cycles under the same injection pressure. The difference of spray patterns may be due to the residual fuel/air bubbles surviving from the last injection or sucking into the nozzle during the needle opening

Guo, Genmiao, He, Zhixia, Wang, Qian, Sun, Shenxin, Chen, Zhou

Comparison of Shadowgraph Imaging, Laser-Doppler Anemometry and X-Ray Imaging for the Analysis of Near Nozzle Velocities of GDI Fuel Injectors

2017-01-2302

10/8/2017

The fuel spray behavior in the near nozzle region of a gasoline injector is challenging to predict due to existing pressure gradients and turbulences of the internal flow and in-nozzle cavitation. Therefore, statistical parameters for spray characterization through experiments must be considered. The characterization of spray velocity fields in the near-nozzle region is of particular importance as the velocity information is crucial in understanding the hydrodynamic processes which take place further downstream during fuel atomization and mixture formation. This knowledge is needed in order to optimize injector nozzles for future requirements. In this study, the results of three experimental approaches for determination of spray velocity in the near-nozzle region are presented. Two different injector nozzle types were measured through high-speed shadowgraph imaging, Laser Doppler Anemometry (LDA) and X-ray imaging. Correlation among these three methods is used to classify the benefits