Study on Underexpanded Impinging Jet Issued from Rectangular Nozzle

This research is concerned primary with pressure distributions and oil flow on the plate to figure out the flow structures for the rectangular nozzles by comparing three-dimensional calculations to the experiments. Flow visualizations were performed using the oil-flow method and schlieren method in our experiments. Underexpanded impinging jet issued from rectangular nozzle of three aspect ratio (1, 3 and 5) were investigated. The flow field was calculated by solving three dimensional compressible Navie-Stokes equations. According to the flow visualization on the plate using oil flow method, it is confirmed that the flow is separated on the impinging plate from center point toward outside at only aspect ratio 1. These experimental results tell us that the flow on the plate avoids the four high pressure areas near the center point only for aspect ratio 1. The corresponding calculations were fairly good agreement with the experimental ones.