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A new impinging nozzle head attached on a normal injection nozzle was designed for improving the performance and combustion of DI diesel engine. Since the fuel is directly injected to the nozzle head at a very short distance from a spray tip of nozzle in a DI diesel engine, the fuel particles will be improved in spray diffusion and distribution. In the case of a prototype injection nozzle with four orifices, the spray angle from each orifice is narrow and similar to the shape of conifer's leaves. By using of the new designed impinging nozzle head, however, an improved spray angle and distribution of fuel and a better starting performance at very low temperature have been observed.

Fuel injected from multi-hole injector with a small injection angle (100°) is impinged to the multi-impingement-wall head(MIW head), which is located in the center of combustion chamber and is attached to the cylinder head. The fuel is diffused into the piston cavity to form a three-dimensional diffusion spray. The main advantage of diffusion spray is that the effects of the fuel impinging diffusion and the collision between fuel particles can be obtained. Based on the concept of MIW head, the experimental results show that the combustion performance and the fuel consumption have been improved. Besides, the NOx, HC and smoke densities of the exhaust gas of a diesel engine have been reduced.

A three-dimensional diffusing spray using the multi-impingement-wall head (MIW head) has been proposed to form air-fuel mixtures in a simple DI diesel engine. In this paper, effects of the width of the MIW head on spray pattern, distribution and engine performance have been investigated. In the fuel spray and engine performance experiments, an optimal width of MIW head results in the collision of fuel particles to advantageous position in a combustion chamber for obtaining a good fuel spray distribution. The minimum BSFC is almost the same value as that of a single DI diesel engine, the HC and smoke densities are reduced and the NOx density is shown a tendency to some increase under part load and decrease under full load. A relatively slow heat release rate and maximum temperature duration of the MIW head can be obtained by shortening the ignition delay.