Impinging jets are used in many engineering and industrial applications, including heating, cooling, drying, food processing, and surface cleaning, among others. The present thesis work is focused on modeling and studying the unsteady wall-pressure signature produced by a jet impinging normally on a flat surface. This study is divided into two main parts:A theoretical part, to establish the beginning step towards building a physics-based, mathematical model to calculate the surface-pressure fluctuation on the impingement surface. The mathematical model is used to explore the effects of changing the flow and jet-vortices parameters, one at a time, on the characteristics of the surface-pressure fluctuation. Three main parameters are examined: vortex-passage frequency, jet Reynolds number, and vortex circulation. An experimental part, to measure the unsteady surface pressure fluctuation on the impingement surface for an axisymmetric jet at normal incidence. Measurements are done, for Reynold numbers Re_D= 8272 and 24818 (based on the jet diameter (D) and jet exit velocity), using a microphone array extending radially from the stagnation point (r/D=0) into the wall-jet zone (r/D=2.33). Comparison of the model and the experimental results shows that, despite of the model simplicity, certain qualitative features of the unsteady wall pressure are similar within the stagnation zone. This outcome establishes confidence to continue further development of the model in the future.
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