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Aging of a Multi-Hole Diesel Injector and Its Effect on the Rate of Injection

Universitat Politecnica de Valencia-Raul Payri, Francisco Javier Salvador, Jaime Gimeno, Tomas Montiel
  • Technical Paper
  • 2020-01-0829
To be published on 2020-04-14 by SAE International in United States
In order to comply with the increasingly restrictive limits of emissions and fuel consumption, researches are focusing on improving the efficiency of combustion engines. In this area, the aging of the injector and its effect on the injection development is not entirely analyzed. In this work, the rate of injection of a diesel injector at different stages of its lifetime is analyzed. To this end, a multi-hole piezoelectric injector was employed, comparing the injection rate measured at the beginning of its lifetime to the rate provided by the injector after aging, maintaining the same boundary conditions in both measurements. Injection pressures up to 200 MPa were used throughout the experiments. The results showed that the steady-state rate of injection was lower after the injector aged. Furthermore, the injector took a longer time to close the needle and end the injection, in comparison with the measurements done at earlier stages of its lifetime. To explain this phenomenon, measurements of momentum flux for each injector hole were done, and results showed that two holes were partially obstructed.…
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Investigation into the deformation of injector components in a common rail system based on numerical simulation

Beijing Institute of Technology-Dan Xu, Baigang Sun, Qing Yang, Dongwei Wu
  • Technical Paper
  • 2020-01-1398
To be published on 2020-04-14 by SAE International in United States
The deformation of fuel injection system components cannot be disregarded as the pressure of the system increases. In particular, the control plunger and the needle of the solenoid injector tend to deform under high working pressure. Their deformation directly affects the volume of the control plunger chamber and the cross-section area of the fuel that enters the sac. A change in chamber volume influences the characteristics of needle movement, whereas a change in cross-section area influences needle movement and injection quantity. Consequently, the deformation of the injector bring difficulties to the precise control of the fuel injection system. In this study, a ADINA (a finite-element software) model of a BOSCH solenoid injector is established to calculate the structural deformation of the nozzle, the needle and the control plunger under different pressures. The accuracy of the model is validated using experimental data published in prior studies. The validated model is used to calculate the structural deformations of the injector components when the solenoid valve is non-energized and energized. Corresponding results indicate that the maximum deformation location…
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Numerical Investigation and Experimental Comparison of ECN Spray G at Flash Boiling Conditions

AVL List GmbH-Bejoy Mandumpala Devassy, Zvonimir Petranovic, Wilfried Edelbauer
  • Technical Paper
  • 2020-01-0827
To be published on 2020-04-14 by SAE International in United States
Fuel injection is a key process influencing the performance of Gasoline Direct Injection (GDI) Engines. Injecting fuel at elevated temperature can initiate flash boiling which can lead to faster breakup, reduced penetration, and increased spray-cone angle. Thus, it impacts engine efficiency in terms of combustion quality, CO2, NOx and soot emission levels. This research deals with modelling of flash boiling processes occurring in gasoline fuel injectors. The flashing mass transfer rate is modelled by the advanced Hertz-Knudsen model considering the deviation from the thermodynamic-equilibrium conditions. The effect of nucleation-site density and its variation with degree of superheat is studied. The model is validated against benchmark test cases and a substantiated comparison with experiment is achieved. It is noticed that in the edwards’s pipe test case immediately after the removal of the rupture disk, a sudden depressurization occurs at the pipe’s exit resulting in the onset of violent evaporation due to flashing which limits the pressure decrease to a value slightly below the saturation pressure. Later, the flash boiling model is applied to investigate a real-size…
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High Efficiency Intake System Leveraging Exhaust Thermal Boost

Finitronx-Xianzhe Jia
University of Pennsylvania-Qianyu Ouyang
  • Technical Paper
  • 2020-01-0277
To be published on 2020-04-14 by SAE International in United States
This IC engine amelioration tackles the hurdling barrier of ICE’s intrinsic efficacy limit through innovative mechanical design of a consolidated system encompassing intake bypass and coordinating injection mechanism. To be specific, a CFD-optimized passage is constructed alongside the intake and injection design which utilizes multi-stage variable mixing precisely, taking full advantage of exhaust temperature elevation. Regenerative heat gained through exhaust system gives rise to flexible amount of thermal dynamics adjustment to the intake. Furthermore, variable geometry intake port is developed based on maximizing air-fuel interaction rate under different circumstances, where high temperature turbulence optimization is implemented in ANSYS Fluent. Pin-slider mechanic design at intake interface enables modular variable intake routing supporting engine efficiency promotion. Regarding ECU development, integrated valve, intake airflow, as well as injection control are designed to cooperate with each other under the supervisory control module. First, optimal controlled valve system is devised at the junction of bypass, which achieves improved response accuracy and combustion sufficiency with flow and temperature regulation. Secondly, a closed-loop injection control strategy fulfills variable in-cylinder combustion tuning with…
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Comparison of Spray Collapses from Multi-Hole and Single-Hole Injectors Using High-Speed Photography

Harbin Institute of Technology-Yitao Shen
Tsinghua University-Lu Xinhui, Yi Gong, Xiao Ma, Shijin Shuai, Omar Awad
  • Technical Paper
  • 2020-01-0321
To be published on 2020-04-14 by SAE International in United States
In this paper, the differences between multi-hole and single-hole spray contour under the same conditions were compared by using high-speed photography. The difference between the contour area of multi-hole and that of single-hole spray was used as a parameter to describe the degree of spray collapse. Three dimensionless parameters (i.e. degree of superheat, degree of undercooling, and nozzle pressure ratio) were applied to characterize inside-nozzle thermodynamic, outside-nozzle thermodynamic and kinetic factors, respectively. In addition, the relationship between the three dimensionless parameters and the spray collapse was analyzed. A semi-empirical equation was proposed for evaluation of the degree of collapse based on dimensionless parameters of flash and non-flash boiling sprays respectively.
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Durability Study of a Light-Duty High Pressure Common Rail Fuel Injection System Using E10 Gasoline

Aramco Research Center-Tom Tzanetakis, Mark Sellnau, Vincent Costanzo, Michael Traver
Argonne National Laboratory-Aniket Tekawade, Brandon Sforzo, Christopher F. Powell
  • Technical Paper
  • 2020-01-0616
To be published on 2020-04-14 by SAE International in United States
In this study, a 500-hour test cycle was used to evaluate the durability of a prototype high pressure common rail injection system operating up to 1800 bar with E10 gasoline. Some aspects of the hardware were modified from their baseline design in order to accommodate an opposed-piston, two-stroke engine application and mitigate the impacts of exposure to gasoline. Overall system performance was maintained throughout testing as fueling rate and rail pressure targets were continuously achieved. Although evidence of vapor formation in the low-pressure part of the system was observed, there was no significant physical damage to the associated components. Injectors showed no deviation in their flow characteristics after exposure to gasoline and high resolution imaging of the nozzle tips and pilot valve assemblies did not indicate the presence of cavitation damage. The high pressure pump did not exhibit any performance degradation during gasoline testing and teardown analysis after 500 hours showed no evidence of cavitation erosion. Despite the lack of lubricity-improving additives in the gasoline, all other fuel-wetted components survived the test cycle without any…
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A numerical study on the ignition of lean CH4/air mixture by a pre-chamber-initiated turbulent jet

King Abdullah University of Science & Technology-Sangeeth Sanal, Mickael Silva, Ponnya Hlaing, Bengt Johansson, Hong G. Im
Saudi Aramco-Emre Cenker
  • Technical Paper
  • 2020-01-0820
To be published on 2020-04-14 by SAE International in United States
Ultra-lean combustion in a spark-ignited (SI) engine is one of the most promising methods explored to reduce the nitrogen oxides (NOx) emissions and increases engine efficiency by decreasing the peak combustion temperature. However, this leads to an increase in combustion instabilities, hence emissions of unburned hydrocarbons (UHC). A spark ignited stratified pre-chamber combustion system has been demonstrated to overcome the obstacles related to ultra-lean combustion. However, the ignition mechanism of the ultra-lean mixture is not well studied. For that, the turbulent jet forced out of the pre-chamber through the nozzles needs to be well understood. The turbulent jet ignition can be either flame ignition (hot active radicals) or jet ignition (hot combustion products), depending on the pressure gradient and nozzle diameter. This hot jet determines the combustion characteristics of the lean main-chamber mixture and engine performance. Converge CFD code was used in this study, and the model used were validated against the measurements performed in-house. To elucidate the main-chamber ignition mechanism, the spark plug location and the spark timing were varied, resulting in different pressure…
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Transient Internal Nozzle Flow in Transparent Multi-Hole Diesel Injector

Argonne National Laboratory-Brandon Sforzo, Katarzyna Matusik, Christopher F. Powell
Hino Motors, Ltd.-Koji Yasutomi
  • Technical Paper
  • 2020-01-0830
To be published on 2020-04-14 by SAE International in United States
An accurate prediction of internal nozzle flow in fuel injector offers the potential to improve predictions of spray computational fluid dynamics (CFD) in an engine, providing a coupled internal-external calculation or by defining better rate of injection (ROI) profile and spray angle information for Lagrangian parcel computations. Previous research has addressed experiments and computations in transparent nozzles, but less is known about realistic multi-hole diesel injectors compared to single axial-hole fuel injectors. In this study, the transient injector opening and closing is characterized using a transparent multi-hole diesel injector, and compared to that of a single axial hole nozzle (ECN Spray D shape). A real-size five-hole acrylic transparent nozzle was mounted in a high-pressure, constant-flow chamber. Internal nozzle phenomena such as cavitation and gas exchange were visualized by high-speed long-distance microscopy. Through optical observation, we find that the initial sac condition is mostly occupied by gas, and the gas remains relatively long after the start of injection, even longer than the case from a single axial hole, thereby affecting the ramp-up in ROI. Also, pronounced…
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Droplet Behaviors of DI Gasoline Wall Impinging Spray by Spray Slicer

Dalian University of Technology-Chao Wang, Wuqiang Long
Hiroshima University-Hongliang Lou, Keiya Nishida, Youichi Ogata
  • Technical Paper
  • 2020-01-1152
To be published on 2020-04-14 by SAE International in United States
Owing to the small size of engines and high injection pressures, it is difficult to avoid the fuel spray impingement on the combustion cylinder wall and piston head in Direct Injection Spark Ignition (DISI) engine, which is a possible source of hydrocarbons and soot emission. As a result, the droplets size and distribution are significantly important to evaluate the atomization and predict the impingement behaviors, such as stick, spread or splash. However, the microscopic behaviors of droplets are seldom reported due to the high density of small droplets, especially under high pressure conditions. In order to solve this problem, a “spray slicer” was designed to cut the spray before impingement as a sheet one to observe the droplets clearly. The experiment was performed in a constant volume chamber under non-evaporation condition, and a mini-sac injector with single hole was used. The filtering device should be as less intrusive as possible, so to detect a momentum flux distribution corresponding to the un-disturbed free spray. To fulfill this basic requirement, different slicer thickness (Tslicer) were tested by…
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Numerical Investigation of Near Nozzle Flash-Boiling Spray in an Axial-Hole Transparent Nozzle

Hino Motors, Ltd.-Koji Yasutomi
Sandia National Laboratories-Joonsik Hwang, Marco Arienti, Lyle M. Pickett
  • Technical Paper
  • 2020-01-0828
To be published on 2020-04-14 by SAE International in United States
Understanding and prediction of flash-boiling spray behavior in gasoline direct-injection (GDI) engines remains a challenge. In this study, computational fluid dynamics (CFD) simulations using the homogeneous relaxation model (HRM) for not only internal nozzle flow but also external spray were evaluated using CONVERGE software and compared to experimental data. High-speed extinction imaging experiments were carried out in a real-size axial-hole transparent nozzle installed at the tip of machined GDI injector fueled with n-pentane under various ambient pressure conditions (Pa/Ps = 0.07 - 1.39). The width of the spray during injection was assessed by means of projected liquid volume, but the structure and timing for boil-off of liquid within the sac of the injector were also assessed after the end of injection, including cases with different designed sac volumes. Compared to the experiment, the default HRM model produces a more narrow liquid width, and a longer boil-off period, suggesting that the phase-change process is underestimated. When varying the HRM model constant to smaller values to promote evaporation, some level of improvement in predictions was observed, but the spray radial width…