Research Papers: Internal Combustion Engines

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

[+] Author and Article Information
Eiji Ishii

Hitachi, Ltd., Research and Development Group,
832-2, Horiguchi,
Hitachinaka, Ibaraki 312-0034, Japan
e-mail: eiji.ishii.qm@hitachi.com

Kazuki Yoshimura

Hitachi, Ltd., Research and Development Group,
832-2, Horiguchi,
Hitachinaka, Ibaraki 312-0034, Japan
e-mail: kazuki.yoshimura.ox@hitachi.com

Yoshihito Yasukawa

Hitachi, Ltd., Research and Development Group,
832-2, Horiguchi,
Hitachinaka, Ibaraki 312-0034, Japan
e-mail: yoshihito.yasukawa.uw@hitachi.com

Hideharu Ehara

Hitachi Automotive Systems, Ltd.,
2520 Takaba,
Hitachinaka, Ibaraki 312-8503, Japan
e-mail: hideharu.ehara.kz@hitachi-automotive.co.jp

Contributed by the IC Engine Division of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received December 11, 2016; final manuscript received February 18, 2017; published online April 19, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(9), 092804 (Apr 19, 2017) (7 pages) Paper No: GTP-16-1580; doi: 10.1115/1.4036285 History: Received December 11, 2016; Revised February 18, 2017

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.

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Fig. 1

Simulation model of air/fuel mixture during opening and closing of valve

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Fig. 2

MPS and CIP procedures in hybrid method

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Fig. 3

Definition of distance from interface. θCIP is volume fraction of liquid. The position of the free surface is defined as 0.5 of the volume fraction of liquid given by CIP. δ is the distance defined at the particle coordinates as the number of cells from a free surface.

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Fig. 4

Definition of a droplet in data-sampling region. Grid size of data-sampling region is same as initial distance between particles in MPS.

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Fig. 5

Experimental equipment for measuring valve lift

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Fig. 6

Apparatus for measuring spray pattern with xenon flash lamp

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Fig. 7

Computational grids used in (a) inner flow simulation (polyhedral grids, and extended view around nozzles in right figure), (b) fuel breakup simulation (hexahedron grids, and bottom view in right figure), and (c) air/fuel mixture simulation (Cartesian girds)

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Fig. 8

Nondimensional flow rate that was used to determine the inlet boundary condition in fuel breakup simulation

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Fig. 9

Effects of threshold of valve lift to start regenerating finer computational grids on simulated flow rate

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Fig. 10

Comparison of simulated fuel breakups near nozzle outlets with measurements around opening valve: (a) simulations and (b) measurements

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Fig. 11

Comparisons of air/fuel mixtures with measured ones at 1.6 ms and 2.5 ms: (a) simulations and (b) measurements

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Fig. 12

Effects of particle density of DDM droplets on air fuel mixture

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Fig. 13

Comparisons of simulated penetrations of beams through nozzles no. 1, 2 and 4 with measured ones

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Fig. 14

Effects of opening and closing of valve on air/fuel mixtures: (a) with opening and closing of valve and (b) without opening and closing of valve




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