Toshiharu Nogi

Mixture formation of fuel injection systems in gasoline engines

Mixture formation technology for gasoline engine multipoint fuel injection systems has been investigated. The fuel injectors spray, the volatility of droplets floating in the air flow, the movement of droplets around the intake valves upper surface, the volatility of droplets on heated surfaces, and the process of atomizing droplets in the intake valve air flow was analyzed. Droplet diameters and spray patterns for good mixture formation without liquid film in cylinders have been clarified

In-cylinder airflow of automotive engine by quasi-direct numerical simulation

Abstract A Computational Fluid Dynamics (CFD) program for in-cylinder airflow analysis has been developed by the authors. The feature of the developed program is that it treats turbulence flow with the quasi-direct numerical simulation (Quasi-DNS). So it is possible to present transient turbulence eddy motions in detail. For fast and high quality mesh generation, the Voxel method was employed. The computational domain is discretized by uniform cubic cells in this method. The simulation results were verified by two benchmark tests. One of them in common use is a backward step flow test, the other is an in-cylinder flow test that supposed the engine induction stroke. Good agreement was obtained between the simulation and the experimental results of these benchmark tests.

Numerical analysis for mixture formation in direct fuel injection spark ignition engines

Abstract Influences of fuel-spray specifications on mixture formation of direct fuel injection spark ignition engines were studied. Fuel-spray, mixture and combustion gas behavior was calculated by numerical simulation and the following results were obtained. The amount of attached fuel on a piston for the stratified charge mode is less using skewed type spray than for non-skewed type spray. This leads to faster flame propagation near the piston surface.

The atomization characteristics of a vibration type atomizer when fuel is supplied intermittently.

The atomization characteristhcs of an atomizer of the ultrasonic vibration type are investigated when fuel is supplied intermittently to the vibration member. The interval time of the liquid supply is 100ms and the supply period is varied from 5ms to 20ms. The mean diameter, velocity, and flow rate of the spray are measured by a phase doppler-type analyzer. The velocity is 0.2-1.0m/s and the mean diameter is 70-90μm. When the fuel is supplied intermittently to the vibratory member, the large size droplet is generated initially. The droplet size is reduced by improving the vibratory member shape and controlling vibration.

An analysis of hollow cone spray patterns.

A study was conducted on hollow cone spray which was injected from a pintle-type and swirl-type injector. The effects of the surrounding pressure and liquid temperature on the spray patterns are discussed experimentally and analytically. The calculated results which are based on the hollow cone spray model including the effects of surface tension, centrifugal force and liquid density almost coincide with the experimental results.