Computational Analysis of Supersonic Underexpanded Jets Impinging on an Inclined Flat Plate

Abstract

Supersonic jets impinging on an inclined flat plate is computationally simulated. Plate angle, distance between the nozzle exit and the plate, and the PR (pressure ratio) are parametrically changed for the flow simulations. The results show that there are four mechanisms leading to the localized pressure peaks on the plate surface: (1) stagnation of the main jet flows, (2) normal shock wave in the upstream area, (3) reattachment of the separated flows over the plate surface, (4) interaction between the intermediate tail shock and the plate surface boundary layer. Investigation of intensities of the pressure peaks shows that the pressure peak (1) caused by the stagnation of the main jet flows is almost independent from PR’s, but the pressure peak (2), (3), (4) become higher at lower PR’s. This happens due to the existence of a jet shock intercepting the flow outside and the ambient pressure does not affect to the total pressure of the main jet flows. Some important flow features about the pressure peaks are identified through the present CFD analysis.