Pages 49-50
In this study, the velocity fields near the nozzle exit of swirl injector spray for direct-injection gasoline engine was measured by using the PIV method. The image of liquid sheet velocity near the nozzle exit was enabled to be captured by PIV system with the long distance microscope and the double-frame CCD camera. Since the liquid sheet velocity was extremely fast, the measurement condition was optimized with changing interrogation area, pulse width, overlap, and so on. PIV images were obtained under the conditions of the injection pressure (5MPa) and two ambient pressures (0.1,0.5MPa). Consequently, the influence of the ambient pressure for the liquid sheet velocity was clarified. The main results obtained here are as follows. Increasing the ambient pressure reduces the liquid sheet velocity near the nozzle exit. The average of liquid sheet velocity under the steady state is 113 m/s when the ambient pressure is 0.1 MPa and about 71 m/s when the ambient pressure is 0.5 MPa.
