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 Coarse Droplet and Liquid Column Formed Around Nozzle Outlets due to Valve Wobble of a GDI Injector

2017 ◽  
Author(s):  
Eiji Ishii ◽  
Yoshihito Yasukawa ◽  
Kazuki Yoshimura ◽  
Kiyotaka Ogura
Keyword(s):  
Surface Tension ◽  
Particulate Matter ◽  
Body Surface ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Fuel Spray ◽  
Direct Injection Engines ◽  
Fuel Injectors ◽  
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 that are formed by non-uniform air/fuel mixtures, coarse droplets generated during end-of-injection, and fuel adhering to the nozzle body surface and piston surface. Uniform air/fuel mixtures and short fuel-spray durations with multiple injections are effective in enabling the valves of fuel injectors to not 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 degrees. 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 degrees.

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.

scholarly journals Impact of bio-alcohol fuels combustion on particulate matter morphology from efficient gasoline direct injection engines

2018 ◽  
Vol 230 ◽  
pp. 794-802 ◽  
Author(s):  
C. Hergueta ◽  
A. Tsolakis ◽  
J.M. Herreros ◽  
M. Bogarra ◽  
E. Price ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Direct Injection Engines ◽  
Alcohol Fuels

Advanced Numerical Approach to Simulate GDI Sprays Under Engine-Like Conditions

2014 ◽  
Author(s):  
Eiji Ishii ◽  
Motoyuki Abe ◽  
Hideharu Ehara ◽  
Yoshihito Yasukawa
Keyword(s):  
Flow Direction ◽  
Direct Injection ◽  
Fuel Mixture ◽  
Numerical Approach ◽  
Gasoline Direct Injection ◽  
Fuel Spray ◽  
Density Region ◽  
Penetration Length ◽  
Spray Penetration ◽  
Fuel Injectors

Gasoline direct-injection (GDI) engines provide both higher engine power and better fuel efficiency than port-injection gasoline engines. However, they emit more particulate matter (PM) than the latter engines. Fuel stuck on walls of pistons and combustion chambers forms a high-density region of fuel in the air/fuel mixture, which becomes a source of PM. To decrease the amount of PM, fuel injectors with short length of spray-penetration are required. A fuel-spray simulation was previously developed; that is, the air/fuel-mixture simulation was integrated with the liquid-column-breakup simulation. The developed fuel-spray simulation was used to optimize the nozzle shapes of fuel injectors for gasoline direct-injection engines. In the present study, the factors that influence spray-penetration length were identified by the numerical simulation. The simulation results were validated by comparing the simulated spray-penetration length with the measured ones and revealing good agreement between them. Angle α was defined as that formed between the direction of flow entering the nozzle inlet and the direction of flow leaving the nozzle outlet; in other words, a indicates a change of flow direction. It was found that α and spray-penetration length was closely related. Velocity that are accelerated with a were studied, and it was found that the velocity within a plane perpendicular to the center axis of the nozzle increases with increasing α.

scholarly journals Study on Fuel-Spray Pattern Control and Its Injection Device for Gasoline Direct Injection Engines.

2001 ◽  
Vol 67 (658) ◽  
pp. 1583-1590
Author(s):  
Ayumu MIYAJIMA ◽  
Yoshio OKAMOTO ◽  
Yuzo KADOMUKAI ◽  
Shigenori TOGASHI ◽  
Mineo KASHIWAYA
Keyword(s):  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Fuel Spray ◽  
Injection Device ◽  
Spray Pattern ◽  
Direct Injection Engines ◽  
Pattern Control

scholarly journals Collaborative investigation of the internal flow and near-nozzle flow of an eight-hole gasoline injector (Engine Combustion Network Spray G)

2020 ◽  
pp. 146808742091844
Author(s):  
Chinmoy K Mohapatra ◽  
David P Schmidt ◽  
Brandon A Sforozo ◽  
Katarzyna E Matusik ◽  
Zongyu Yue ◽  
...  
Keyword(s):  
Direct Injection ◽  
Internal Flow ◽  
Gasoline Direct Injection ◽  
Two Phase ◽  
Direct Injection Engines ◽  
Fuel Injectors ◽  
Engine Combustion ◽  
Injector Flows ◽  
Eulerian Modeling ◽  
The Impact

The internal details of fuel injectors have a profound impact on the emissions from gasoline direct injection engines. However, the impact of injector design features is not currently understood, due to the difficulty in observing and modeling internal injector flows. Gasoline direct injection flows involve moving geometry, flash boiling, and high levels of turbulent two-phase mixing. In order to better simulate these injectors, five different modeling approaches have been employed to study the engine combustion network Spray G injector. These simulation results have been compared to experimental measurements obtained, among other techniques, with X-ray diagnostics, allowing the predictions to be evaluated and critiqued. The ability of the models to predict mass flow rate through the injector is confirmed, but other features of the predictions vary in their accuracy. The prediction of plume width and fuel mass distribution varies widely, with volume-of-fluid tending to overly concentrate the fuel. All the simulations, however, seem to struggle with predicting fuel dispersion and by inference, jet velocity. This shortcoming of the predictions suggests a need to improve Eulerian modeling of dense fuel jets.

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