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Fuel-spray pattern is one of the most critical factors for obtaining stable combustion. A DI fuel injector in which the fuel-spray pattern can be easily controlled and predicted is therefore essential. Our main goal is to develop a fuel-spray pattern control method that takes into account the influences of ambient pressure and fuel pressure. After deciding how to incline and split the fuel spray, we designed an L-cut orifice nozzle (L-step nozzle) based on a swirl-type injector. We investigated the fuel-spray pattern of the newly designed injector both experimentally and numerically. Experimentally, the L-step nozzle injector was used to spray fuel into an experimental pressure chamber. The resulting spray patterns were visualized by YAG-laser sheet and recorded by CCD cameras. The spray formation was analyzed and the spray patterns were evaluated in terms of spray angle and penetration length. Atomization from the spray in the L-step nozzle injector was also investigated.

We examine experimentally and numerically the influences of nozzle geometry on spray angle and penetration length. Swirl-type DI fuel injectors with an L-cut orifice nozzle (L-type) and a taper-cut orifice nozzle (Taper-type) are newly designed. The new injectors are used to spray fuel inside an experimental pressure chamber. The resulting spray patterns are visualized by YAG-laser sheet and recorded by CCD cameras. These experiments showed that both the L-type and taper-type nozzles can produce an inclined fuel-spray pattern. Furthermore, the fuel-spray pattern can be controlled by changing the depth of the orifice in both nozzles. During the development of the new nozzles, a CFD code for predicting the spray shape are also developed. By comparing the calculated results to the experiments, it was shown that the CFD code can predict the spray angle with reasonable accuracy. The spray angle was found to be strongly dependent on the air void geometry formed inside the orifice.