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.

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

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Eiji Ishii ◽  
Kazuki Yoshimura ◽  
Yoshihito Yasukawa ◽  
Hideharu Ehara
Keyword(s):  
High Speed ◽  
Fuel Mixture ◽  
Fuel Spray ◽  
Fuel Injector ◽  
Engine Emissions ◽  
Fuel Injectors ◽  
Multiple Injections ◽  
Valve Motion ◽  
Fuel Mixtures ◽  
Opening And Closing

Lower engine emissions like CO2, particulate matter (PM), and NOx have recently become more necessary in automobile engines to protect the earth's environment. Keeping uniformity of air/fuel mixture and decreasing fuel adhesion on walls of cylinder and piston are effective in order to reduce the engine emissions. In order to achieve the target fuel-spray, fuel injectors for gasoline direct injection engines need to be designed to deal with multiple injections with high speed of opening and closing of valves. One of the difficulties in the multiple injections is to control fuel-spray behaviors during opening and closing of valve; flow rate and spray penetration which are changed due to slow velocity of fluid during opening and closing of valve cause nonuniformity of air/fuel mixture that results in the increase of PM. 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. In this study, we developed an air/fuel mixture simulation that is connected with an inner-flow simulation with a valve opening and closing function. 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. It was also found that the magnetic circuit with the solenoid needs to be designed to achieve high-speed valve motion and also keeps same valve motion in each injection, especially during opening and closing of valve.

Fuel Spray Simulation With Collision Jets for Automobile Engines

2010 ◽  
Author(s):  
Eiji Ishii ◽  
Yoshihiro Sukegawa ◽  
Hiroshi Yamada
Keyword(s):  
Liquid Film ◽  
Leading Edge ◽  
Particle Method ◽  
Fuel Mixture ◽  
Liquid Films ◽  
Fuel Spray ◽  
Diameter Distribution ◽  
Fuel Injector ◽  
Automobile Engines ◽  
Spray Distribution

Fuel injectors for automobile engines atomize fuel into multi-scale free surfaces: liquid films formed at the fuel-injector outlet, ligaments generated by the liquid-film breakup, and droplets generated from the ligaments within the air/fuel mixture region. We previously developed a fuel spray simulation combining the liquid-film breakup near the injector outlet with the air/fuel mixture. The liquid-film breakup was simulated by a particle method. The fuel-droplet behavior in the air/fuel mixture region was simulated by a discrete droplet model (DDM). In this study, we applied our method to simulate fuel sprays from a fuel injector with collision jets. The simulation results were compared with the measurements—the mean diameter of droplet in spray, D32, was 35 percent larger than measured D32. We also studied the effects of DDM injection conditions on the spray distribution in the air/fuel mixture region—diameter distributions of injected DDM-droplets were given by the liquid-film breakup simulation, or by Nukiyama-Tanazawa’s theory. The diameter distribution of droplets near the injector outlet was found to affect the spray distribution within the air/fuel mixture region, mainly around the leading edge of spray.

A Fuel-Spray Simulation Considering Fuel-Jet Breakup Near Fuel Injector and Composition of Air/Fuel Mixture

2009 ◽  
Author(s):  
Eiji Ishii ◽  
Yoshihito Yasukawa ◽  
Yoshihiro Sukegawa ◽  
Hiroshi Yamada
Keyword(s):  
Liquid Film ◽  
Particle Method ◽  
Fuel Mixture ◽  
New Method ◽  
Fuel Spray ◽  
Fuel Injector ◽  
Scale Free ◽  
Jet Breakup ◽  
Fuel Jet ◽  
Automobile Engines

To simulate multi-scale free surfaces in the fuel spray of an injector for automobile engine, we combined a liquid-film-breakup simulation and an air/fuel-mixture simulation. The liquid-film breakup near the injector outlet was simulated by using a particle method, and the air/fuel mixture after the liquid-film breakup was simulated by using a “discrete droplet model” (DDM). Distributions of droplet diameters and velocities, calculated in the liquid-film breakup simulation, were used as the injection condition of DDM. We applied our new method to simulate the spray from a collision fuel injector. The simulation results were verified by comparing them with measurements. The liquid-film breakup near the injector outlet and the behavior of the air/fuel mixture qualitatively agreed with the measurements. We found that out new method was useful to the fuel-spray simulation for automobile engines.

Ultra-Low Emission Hydrogen/Syngas Combustion With a 1.3 MW Injector Using a Micro-Mixing Lean-Premix System

2011 ◽  
Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Flame Temperature ◽  
Fuel Mixture ◽  
Full Scale ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Nitrogen Dilution ◽  
Fuel Mixtures

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.

Characterization of Spray Formed by Diesel-Water Mixture Jet Injected Into an Air Crossflow

2017 ◽  
Author(s):  
Jinkwan Song ◽  
Jong Guen Lee
Keyword(s):  
Diesel Fuel ◽  
Drop Size ◽  
Pure Water ◽  
Fuel Mixture ◽  
Water Mixture ◽  
Fuel Injector ◽  
Spray Characteristics ◽  
Two Fluids ◽  
Mixing Ratios ◽  
Fuel Mixtures

Using a mixture of water and diesel fuel is considered a way to reduce gas emissions including NOx and COx in the gas turbine. This paper presents experimental results on spray characteristics of the water-diesel fuel mixture in an air crossflow. A plain-orifice type injector of 0.508 mm in diameter is employed in the research. Pure water, pure diesel fuel, and water-diesel fuel mixtures with different mixing ratios are used to compare their spray characteristics. In order to observe spray behaviors in different breakup regimes, Weber numbers for water of 30 and 125 are chosen as the operating condition and the corresponding Weber numbers for diesel fuel at the same conditions are 92 and 382, respectively. Momentum flux ratios are 10 and 20. A tee connection and a subsequent static mixer are employed at upstream of fuel injector to mix two liquids. Phase Doppler Particle Analyzer (PDPA) measurement is performed to measure droplet distributions and mean drop size at various mixture ratios, and planar laser induced fluorescence (PLIF) technique with dyeing either diesel or water is used to look into the primary breakup process. PDPA data show that the spray characteristics of water-diesel fuel mixtures such as mean drop size and number density distribution can be predicted from the measured drop size distribution of pure fluids by weighting those quantities by mass fraction of each fluid, indicating that the water and diesel are injected alternately without significant mixing between the two fluids. A short transition of liquid flow from water-to-diesel or diesel-to-water produces small fraction of relatively bigger droplets.

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.

Simulation of Liquid Jet Breakup of a Swirl-Type Fuel Injector for Automobile Engines

2007 ◽  
Author(s):  
Eiji Ishii ◽  
Toru Ishikawa ◽  
Yoshiyuki Tanabe
Keyword(s):  
Water Column ◽  
Grid Method ◽  
Particle Method ◽  
Engine Fuel ◽  
Fuel Injector ◽  
Free Surfaces ◽  
Scale Free ◽  
Multi Scale ◽  
Jet Breakup ◽  
Automobile Engines

To simulate multi-scale free surfaces, we developed a hybrid particle/grid method by which the free surfaces within sub-grid regions are simulated by the particle method, and other regions are simulated with the grid method. The particle method uses two types of particles to model gas and liquid fluids in order to simulate the interaction between them. We tested the new method on fragmentation of a water column, and the predicted configurations of the water column are consistent with measurements of Koshizuka and Oka. We also simulated the fuel spray near the outlet of an automobile-engine fuel injector and found that this method qualitatively simulated the breakup of the liquid film.

Secondary-Drop-Breakup Simulation Integrated With Fuel-Breakup Simulation Near Injector Outlet

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Eiji Ishii ◽  
Masanori Ishikawa ◽  
Yoshihiro Sukegawa ◽  
Hiroshi Yamada
Keyword(s):  
Liquid Film ◽  
Particle Method ◽  
Liquid Films ◽  
Fuel Spray ◽  
Fuel Injector ◽  
Drop Breakup ◽  
Free Surfaces ◽  
Collision Type ◽  
Automobile Engines ◽  
Secondary Drop

The fuel spray of an injector for automobile engines contains multiscale free surfaces: liquid films formed at the fuel-injector outlet, ligaments generated by liquid-film breakup, and droplets generated from the ligaments within the secondary-drop-breakup region. To simulate these multiscale free surfaces, we developed a method that combines two types of simulation. The liquid-film breakup near the injector outlet was simulated by using a particle method, and the secondary-drop breakup after the liquid-film breakup was simulated by using a discrete droplet model (DDM). The injection conditions of DDM were the distributions of droplet diameters and velocities calculated in the liquid-film-breakup simulation. We applied our method to simulate the spray from a collision-type fuel injector. The simulated liquid-film breakup near the injector outlet and behavior of the secondary-drop breakup qualitatively agreed with measurements. Furthermore, the errors of the mean droplet diameters between the simulations and the measurements were less than 12%. This shows that our method is effective for fuel spray simulation.

Fuel-Spray Simulation With Valve Motion Perpendicular to Closing Direction

2017 ◽  
Author(s):  
Eiji Ishii ◽  
Yoshihito Yasukawa ◽  
Kazuki Yoshimura ◽  
Kiyotaka Ogura
Keyword(s):  
Flow Simulation ◽  
Grid Method ◽  
Ccd Camera ◽  
Particle Method ◽  
Fuel Mixture ◽  
Fuel Spray ◽  
Fuel Injector ◽  
Multiple Injections ◽  
Fuel Sprays ◽  
Valve Motion

Particulate matter (PM) in exhaust gas from automotive engines causes air pollution. Multiple injections of fuel into the combustion chamber is one of the solutions to decrease PM; a uniform air/fuel mixture and short fuel-spray duration by using multiple injections are effective to decrease PM. To form the uniform air/fuel mixture, fuel sprays from fuel injectors needs to be uniform during injections. Unsteady valve-motions, especially those perpendicular to the closing direction, cause spray swings that form un-uniformity of air/fuel mixture. It is difficult to measure valve motions in the space of a few micrometer within a stainless steel body during fuel injections. Fuel-spray simulation is useful to study the effect of valve motion on the un-uniformity of fuel sprays. In fuel-spray simulation, jets passing through nozzles need to be simulated with the valve motion. We previously developed a particle/grid hybrid method that integrated the inner flow simulation using a grid method with a fuel breakup simulation using a particle method. In this study, we studied the effects of valve motions perpendicular to the closing direction on fuel sprays in order to decrease the un-uniformity of air/fuel mixture. First, we observed fuel-spray behaviors during measurements; a fuel injector with multi-holes was selected, and spray patterns were recorded by a CCD camera with a Xenon flash lamp. The jets passing through the nozzles changed their profiles over time, and the widths of the jets changed from thin to thick at almost the same time. The simulated spray behaviors with valve motion in the front-to-rear direction showed the same trends as those in measurement. It is assumed that because the positions of the six nozzles on the orifice cup were assigned asymmetrically in the front-to-rear direction, asymmetric flow distribution caused the valve motion.

Short Spray-Penetration for Direct Injection Gasoline-Engines With Numerical Simulation

2013 ◽  
Author(s):  
Eiji Ishii ◽  
Motoyuki Abe ◽  
Hideharu Ehara ◽  
Tohru Ishikawa
Keyword(s):  
High Speed ◽  
Direct Injection ◽  
Grid Method ◽  
Particle Method ◽  
Fuel Mixture ◽  
Liquid Column ◽  
Fuel Spray ◽  
Spray Penetration ◽  
Fuel Injectors ◽  
Gasoline Engines

Direct injection gasoline-engines have both better engine power and fuel efficiency than port injection gasoline-engines. However, direct injection gasoline-engines also emit more particulate matter (PM) than port injection gasoline-engines do. To decrease PM, fuel injectors with short spray-penetration are required. More effective fuel injectors can be preliminarily designed by numerically simulating fuel spray. We previously developed a fuel-spray simulation. Both the fuel flow within the flow paths of an injector and the liquid column at the injector outlet were simulated by using a grid method. The liquid-column breakup was simulated by using a particle method. The motion of droplets within the air/fuel mixture (secondary-drop-breakup) region was calculated by using a discrete droplet model (DDM). In this study, we applied our fuel-spray simulation to sprays for the direct injection gasoline-engines. Simulated spray penetrations agreed relatively well with measured spray penetrations. Velocity distributions at the outlet of three kinds of nozzles were plotted by using a histogram, and the relationship between the velocity distributions and spray penetrations was studied. We found that shrinking the high-speed region and making the velocity-distribution uniform were required for short spray penetration.

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