Study on Fuel-Spray Pattern Control and Its Injection Device for Gasoline Direct Injection Engines

Fuel-spray patterns are critical to stable combustion. As a result, a DI fuel injector in which the fuel-spray pattern can easily be controlled is essential to design an in-cylinder configuration. Our main goal was to develop a fuel-spray pattern control method that takes into account the influences of ambient and fuel pressures. A swirl-type DI fuel injector with an L-cut orifice nozzle (L-step nozzle) is newly designed. Experimentally and numerically we investigate the influences of its nozzle geometry on the spray angle and penetration length. In our experiments, fuel spray was injected inside a pressure chamber by using the new injector. The resulting spray patterns were visualized by using a YAG-laser sheet and recorded by using CCD cameras. These experiments showed that our L-step nozzle produces an inclined and split fuel-spray pattern. The fuel was well atomized by using our new nozzle. A CFD was performed to analyze the mechanism for inclining fuel spray pattern. Comparing the experimental and numerical results showed that the code accurately predicted the spray angle. The spray angle was found to be dependent on the air void geometry inside the orifice. We also found that the fuel-spray pattern could be controlled by changing the depth of the orifice.