Experimental study of flowfield and pressure fluctuation of a supersonic impinging jet

This experiment investigates flowfield characteristics, shock structure, and pressure fluctuation of a supersonic impinging jet for various nozzle to plate distances and nozzle pressure ratios (NPRs). The plate distances analyzed were 10 mm, 20 mm, and 30 mm and the NPRs investigated were 2.77, 3.72, and 4.81. The Schlieren imaging technique was used to observe the shock structure of the impinging jet system. Pressure transducers were used in order to analyze the frequencies of pressure fluctuation generated by the shock propagation of the impinging jet and determine the effects of each independent variable and their interactions. Particle Image Velocimetry (PIV) measurements were performed at the central plane of the nozzle near the impingement surface. From PIV measurements, velocity vector fields, flow characteristics, mean velocity, Turbulent Kinetic Energy, and Reynolds stress profiles were computed. Good agreement was observed between both the Schlieren imaging and PIV techniques. The Schlieren imaging and pressure measurements were useful in studying and understanding the shock structure and its potential effects.