Experimental and Numerical Approach to Fuel Spray Control for Fuel Injectors

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. Numerically, a CFD code was developed in order to predict the spray shape. A comparison between experimental and numerical results showed that the accuracy of the prediction of the spray angle was in good agreement. The spray angle was found to be strongly dependent on the air void geometry formed inside the orifice. Finally, it was also found that the fuel-spray pattern can be controlled by changing depth of the orifice.