Late-Fuel Simulation Near Nozzle Outlet of Fuel Injector During Closing Valve

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Eiji Ishii ◽  
Kazuki Yoshimura ◽  
Yoshihito Yasukawa ◽  
Hideharu Ehara
Keyword(s):  
Surface Tension ◽  
Hybrid Method ◽  
Particle Method ◽  
Particulate Matters ◽  
Fuel Injector ◽  
Nozzle Outlet ◽  
Flow Paths ◽  
Fuel Injectors ◽  
Low Speed ◽  
Fuel Behavior

Late fuel during closing of the valve of a fuel injector and fuel films stuck on the wall around the nozzle outlets are sources of particulate matters (PM). In this study, we focused on the effects of the valve motions on the late fuel and the fuel films stuck on the walls around the nozzle outlets. We previously developed a particle/grid hybrid method: fuel flows within the flow paths of fuel injectors were simulated by a front capturing method, and liquid-column breakup at the nozzle outlets was mainly simulated by a particle method. The velocity at the inlet boundary of a fuel injector was controlled in order to affect the valve motions on the late-fuel behavior. The simulated late fuel broke up with surface tension around the time of zero-stroke position of the valve, then liquid columns and coarse droplets formed after the bounds of the valve, and finally only coarse droplets were left. We found that the late fuel was generated by low-speed fuel-flows through the nozzles during the bounds of the valve. The effect of the bounds of the valve on the fuel films stuck on the wall around the nozzle outlets was also studied with a simulation that removed the bounds of the valve. The volume of the fuel films stuck on the wall of the nozzle outlets decreased without the bounds of the valve.

Late-Fuel Simulation Near Nozzle Outlet of Fuel Injector During Closing Valve

2015 ◽  
Author(s):  
Eiji Ishii ◽  
Kazuki Yoshimura ◽  
Yoshihito Yasukawa ◽  
Hideharu Ehara
Keyword(s):  
Surface Tension ◽  
Hybrid Method ◽  
Particle Method ◽  
Liquid Column ◽  
Fuel Injector ◽  
Nozzle Outlet ◽  
Flow Paths ◽  
Fuel Injectors ◽  
Low Speed ◽  
Fuel Behavior

Late fuel during closing of the valve of a fuel-injector and fuel films stuck on the wall around the nozzle outlets are sources of PM. In this study, we focused on effects of the valve motions on the late fuel and the fuel films stuck on the walls around the nozzle outlets. We previously developed a particle/grid hybrid method: fuel flows within the flow paths of fuel injectors were simulated by a front capturing method, and liquid-column breakup at the nozzle outlets was mainly simulated by a particle method. The velocity at the inlet boundary of a fuel injector was controlled in order to affect the valve motions on the late-fuel behavior. The simulated late fuel broke up with surface-tension around the time of zero-stroke position of the valve, then liquid columns and coarse droplets formed after the bounds of the valve, and finally only coarse droplets were left. We found that the late fuel was generated by low-speed fuel-flows through the nozzles during the bounds of the valve. The effect of the bounds of the valve on the fuel films stuck on the wall around the nozzle outlets was also studied with a simulation that removed the bounds of the valve. The volume of the fuel films stuck on the wall of the nozzle outlets decreased without the bounds of the valve.

Cavitation in Transient Flows Through a Micro-Nozzle

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
E. Sanmiguel-Rojas ◽  
P. Gutierrez-Castillo ◽  
C. del Pino ◽  
J. A. Auñón-Hidalgo
Keyword(s):  
Three Dimensional ◽  
Pollutant Emissions ◽  
Moderate Pressure ◽  
Fuel Injector ◽  
Nozzle Outlet ◽  
Fuel Injectors ◽  
Pressure Drops ◽  
Transient Flows ◽  
Micro Nozzle ◽  
Lack Of Information

High cavitating or supercavitating flows in fuel injector systems are crucial since they improve the mixing and the fuel atomization into combustion chambers, decreasing both fuel consumption and pollutant emissions. However, there is a lack of information regarding the required time to obtain high cavitating flows at the nozzle outlet, from the start of the injection pulse. In this work, a new method to quantify the time to get supercavitating flows at the nozzle outlet is developed. In particular, the delay in the inception of a supercavitating flow through a micronozzle is numerically analyzed for different pressure drops in a well-studied benchmark for fuel injectors. The three-dimensional simulations show that a delay higher than 100 μs is necessary for moderate pressure drops. Nevertheless, the delay tends to decay by rising amplitudes of the pressure pulse, reaching a saturation value of around 65 μs.

Effects of Opening and Closing Fuel-Injector Valve on Air/Fuel Mixture

2016 ◽  
Author(s):  
Eiji Ishii ◽  
Kazuki Yoshimura ◽  
Yoshihito Yasukawa ◽  
Hideharu Ehara
Keyword(s):  
Fuel Efficiency ◽  
Particle Method ◽  
Fuel Mixture ◽  
Fuel Injector ◽  
Injection Point ◽  
Fuel Injectors ◽  
Automobile Engines ◽  
Valve Opening ◽  
Fuel Mixtures ◽  
Opening And Closing

Lower engine emissions and improved fuel efficiency have recently become more necessary in automobile engines. Fuel injectors need to be designed to decrease late fuel during valve closing and to deal with multiple injections. Fuel-spray behaviors are controlled by the valve-lifts of fuel injectors; therefore, air/fuel mixture simulations that integrate with inner flow simulations in fuel injectors during the opening and closing of valves are essential for studying the effects of valve motions on air/fuel mixtures. We previously developed a late-fuel simulation near the nozzle outlets of a fuel injector during valve closing; fuel flows within the flow paths of the fuel injector were simulated by a front capturing method, and fuel breakups near the nozzle outlets were mainly simulated by a particle method. The inlet boundary of the fuel injector was controlled in order to affect the valve motions on the late-fuel behavior. In this study, we improved the late-fuel simulation by adding a valve opening function. The motion of droplets within the air/fuel mixture region was calculated by using a discrete droplet model (DDM). The injection conditions for the DDM were defined with the results of the improved late-fuel simulation; positions and velocities of droplets at the injection point were defined by using the results of the late-fuel simulation. The simulation results were validated by comparing the simulated fuel breakup near the nozzle outlets and the air/fuel mixtures in the air region with the measured ones, revealing good agreement between them. The effects of opening and closing the valve on the air/fuel mixtures were also studied; the opening and closing of the valve affected the front and rear behaviors of the air/fuel mixture and also affected spray penetrations. The developed simulation was found to be an effective tool for studying the effects of valve motions on the air/fuel mixtures.

Particle/CIP Hybrid Method for Predicting Motions of Micro and Macro Free Surfaces

Volume 3 ◽  
2004 ◽  
Author(s):  
Eiji Ishii ◽  
Toru Ishikawa ◽  
Yoshiyuki Tanabe
Keyword(s):  
Liquid Film ◽  
Hybrid Method ◽  
Volume Fraction ◽  
Particle Method ◽  
Liquid Films ◽  
Liquid Column ◽  
Cip Method ◽  
Fuel Injector ◽  
Free Surfaces ◽  
Liquid Flows

To predict motions of micro and macro free surfaces simultaneously within gas-liquid flows, we have developed a particle/CIP (Cubic Interpolated Propagation) hybrid method. The micro free surfaces (smaller than grid sizes) were simulated by the particle method, and the macro free surfaces (larger than grid sizes) were simulated by the CIP method. And then the particles used in the particle method were assigned near the macro free surfaces by using volume fraction of liquid that was calculated by the CIP method. The developed method was used to predict the collapse of a liquid column. Namely, it predicted both the large deformation of the liquid column and the fragmentation of it simultaneously, and the predicted configurations of the liquid column agreed well with the experimentally measured ones. It was also used to predict breakup of liquid films in a fuel injector used for engines of automobiles, and the predicted profile of the liquid film was sharp in an air region where the thickness of the liquid film became thinner than the grid sizes.

The Civic: A Concept in Vortex Induced Combustion for the Solar Gemini 10 kW Gas Turbine

1981 ◽  
Vol 103 (1) ◽  
pp. 34-42 ◽  
Author(s):  
J. R. Shekleton
Keyword(s):  
Gas Turbine ◽  
Diffusion Flames ◽  
Reynolds Numbers ◽  
Flame Stabilization ◽  
Fuel Injector ◽  
Combustion Chambers ◽  
Turbine Generator ◽  
Fuel Injectors ◽  
Swirl Flame ◽  
Combustion Processes

The Radial Engine Division of Solar Turbines International, an Operating Group of International Harvester, under contract to the U.S. Army Mobility Equipment Research & Development Command, developed and qualified a 10 kW gas turbine generator set. The very small size of the gas turbine created problems and, in the combustor, novel solutions were necessary. Differing types of fuel injectors, combustion chambers, and flame stabilizing methods were investigated. The arrangement chosen had a rotating cup fuel injector, in a can combustor, with conventional swirl flame stabilization but was devoid of the usual jet stirred recirculation. The use of centrifugal force to control combustion conferred substantial benefit (Rayleigh Instability Criteria). Three types of combustion processes were identified: stratified and unstratified charge (diffusion flames) and pre-mix. Emphasis is placed on five nondimensional groups (Richardson, Bagnold, Damko¨hler, Mach, and Reynolds numbers) for the better control of these combustion processes.

Simulation of Coarse Droplet and Liquid Column Formed around Nozzle Outlets Due to Valve Wobble of a Gasoline Direct Injection Injector

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Eiji Ishii ◽  
Yoshihito Yasukawa ◽  
Kazuki Yoshimura ◽  
Kiyotaka Ogura
Keyword(s):  
Surface Tension ◽  
Particulate Matter ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Fuel Spray ◽  
Direct Injection Engines ◽  
Fuel Injectors ◽  
Multiple Injections ◽  
Fuel Mixtures ◽  
Opening And Closing

The generation of particulate matter (PM) is one problem with gasoline direct-injection engines. PM is generated in high-density regions of fuel. Uniform air/fuel mixtures and short fuel-spray durations with multiple injections are effective in enabling the valves of fuel injectors not to wobble and dribble. We previously studied what effects the opening and closing of valves had on fuel spray behavior and found that valve motions in the opening and closing directions affected spray behavior and generated coarse droplets during the end-of-injection. We focused on the effects of valve wobbling on fuel spray behavior in this study, especially on the behavior during the end-of-injection. The effects of wobbling on fuel spray with full valve strokes were first studied, and we found that simulated spray behaviors agreed well with the measured ones. We also studied the effects on fuel dribble during end-of-injection. When a valve wobbled from left to right, the fuel dribble decreased in comparison with a case without wobbling. When a valve wobbled from the front to the rear, however, fuel dribble increased. Surface tension significantly affected fuel dribble, especially in forming low-speed liquid columns and coarse droplets. Fuel dribble was simulated while changing the wetting angle on walls from 60 to 5 deg. We found that the appearance of coarse droplets in sprays decreased during the end-of-injection by changing the wetting angles from 60 to 5 deg.

Vortex ring-like structures in gasoline fuel sprays under cold-start conditions

2009 ◽  
Vol 10 (4) ◽  
pp. 195-214 ◽  
Author(s):  
S Begg ◽  
F Kaplanski ◽  
S Sazhin ◽  
M Hindle ◽  
M Heikal
Keyword(s):  
Vortex Ring ◽  
High Speed ◽  
Phenomenological Study ◽  
Theoretical Models ◽  
High Speed Photography ◽  
Fuel Injector ◽  
Fuel Injectors ◽  
Fuel Sprays ◽  
Phase Doppler Anemometry ◽  
Ring Model

A phenomenological study of vortex ring-like structures in gasoline fuel sprays is presented for two types of production fuel injectors: a low-pressure, port fuel injector (PFI) and a high-pressure atomizer that injects fuel directly into an engine combustion chamber (G-DI). High-speed photography and phase Doppler anemometry (PDA) were used to study the fuel sprays. In general, each spray was seen to comprise three distinct periods: an initial, unsteady phase; a quasi-steady injection phase; and an exponential trailing phase. For both injectors, vortex ring-like structures could be clearly traced in the tail of the sprays. The location of the region of maximal vorticity of the droplet and gas mixture was used to calculate the temporal evolution of the radial and axial components of the translational velocity of the vortex ring-like structures. The radial components of this velocity remained close to zero in both cases. The experimental results were used to evaluate the robustness of previously developed models of laminar and turbulent vortex rings. The normalized time, , and normalized axial velocity, , were introduced, where tinit is the time of initial observation of vortex ring-like structures. The time dependence of on was approximated as and for the PFI and G-DI sprays respectively. The G-DI spray compared favourably with the analytical vortex ring model, predicting , in the limit of long times, where α = 3/2 in the laminar case and α = 3/4 when the effects of turbulence are taken into account. The results for the PFI spray do not seem to be compatible with the predictions of the available theoretical models.

The Effect of the Fuel Injector Internal Geometry Upon the Primary Zone Aerodynamics

1998 ◽  
Author(s):  
R. A. Hicks ◽  
M. Whiteman ◽  
C. W. Wilson
Keyword(s):  
Boundary Conditions ◽  
Fluid Dynamic ◽  
Radial Component ◽  
Fuel Injector ◽  
Air Blast ◽  
Fuel Injectors ◽  
Cfd Models ◽  
Primary Zone ◽  
Flow Through ◽  
Semi Empirical

One of the major aims of research in gas turbine combustor systems is the minimisation of non-desirable emissions. The primary method of reducing pollutants such as soot and NOx has been to run the combustion primary zone lean. Unfortunately, this causes problems when the combustor is run under idle and relight conditions as the primary zone air fuel ratio (AFR) can exceed the flammability limit. Altering this AFR directly affects the primary zone aerodynamics through changes in the spray profile. One method of determining the influence of changes in AFR upon the primary zone is to use Computational Fluid Dynamic (CFD) models. However, to model the flow through an air-blast fuel injector and accurately predict the resulting primary zone aerodynamics requires hundreds of thousands, if not millions, of cells. Therefore, with current computer capabilities simplifications need to be made. One simplification is to model the primary zone as a 2-D case. This reduces the number of cells to a computationally solvable level. However, by reducing the problem to 2-D the ability to accurately model air-blast fuel injectors is lost as they are intrinsically 3-D devices. Therefore, it is necessary to define boundary conditions for the fuel injector. Currently, due to difficulties in obtaining experimental measurements inside a air-blast fuel injector, these boundary conditions are often derived using semi-empirical methods. This paper presents and compares two such models; the model proposed by Crocker et al. in 1996 and one developed at DERA specifically for modelling air-blast fuel injectors. The work also highlights the importance of the often neglected radial component upon the primary zone aerodynamics.

On-Site Emissions and Fuel Consumption Measurement to Compare Locomotive Fuel Injector Performance

2006 ◽  
Author(s):  
W. Scott Wayne ◽  
Ryan A. Barnett ◽  
Jeffrey M. Cutright ◽  
Ted E. Stewart
Keyword(s):  
West Virginia ◽  
Fuel Consumption ◽  
Alternative Fuels ◽  
Engine Performance ◽  
Combustion Efficiency ◽  
Fuel Injector ◽  
West Virginia University ◽  
Test Procedures ◽  
Fuel Injectors ◽  
Locomotive Engine

As part of the Norfolk-Southern Railroad’s on-going investigation into fuel consumption reductions for their fleet of 3000 locomotives, the Center for Alternative Fuels, Engines and Emissions at West Virginia University conducted on-site locomotive engine performance and emissions measurements to characterize the performance, fuel consumption and emissions associated with fuel injectors from two injector suppliers. Emissions and fuel consumption were measured using the West Virginia University Transportable Locomotive Emissions Testing Laboratory, which was set up at the Norfolk-Southern Heavy Repair Facility in Roanoke, Virginia. The tests were conducted to evaluate potential emissions and fuel consumption differences between two fuel injector suppliers using an EMD GP38-2 locomotive equipped with a 2100 hp (1566 kW), 16-cylinder, EMD 16-645E engine. The test locomotive engine was freshly overhauled and certified to the EPA locomotive Tier 0 emissions standards. Emissions and fuel consumption measurements were conducted according to the Federal Test Procedures defined in the Code of Federal Regulations 40CFR Part 92 Subpart B [1]. The engine was first tested in the “as overhauled” configuration with the OEM fuel injectors to establish the baseline emissions and fuel consumption. The baseline FTP results confirmed that this locomotive was in compliance with the Federal Tier 0 emissions standards. The OEM specification fuel injectors were replaced with “Fuel Saver” injectors designed and manufactured by an aftermarket injector supplier referred to in this paper as Supplier B. The Supplier B injectors reduced fuel consumption on the average of 2–4% for each notch, except for Notch 4 and Low Idle. However, the Supplier B injectors increased the NOx levels by 20–30% for almost every notch, which is an expected result due to the improved combustion efficiency.

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