Impingement of Slightly Underexpanded Sonic Jets onto a Perpendicular Flat Plate

摘要

The flow field produced by an air jet from a sonic nozzle impinging upon a perpendicular flat plate was studied. The nozzle was operated at values of Pc/Pa between 1.5 and 6.0. The free jet was investigated by obtaining pitot pressure distributions at separation distances of 2, 3, and 5 nozzle exit diameters. With the plate set perpendicular to the flow at the same separations, pressure distributions across a diameter were obtained. The structure of the free and impinging jets was investigated using Schlieren photography. The skin friction properties of the flow field on the plate surface were investigated. The impinging flow is subject to jet/plate shock interference phenomena which are more apparent at smaller plate separation distances. The results of the skin friction investigation confirm the flow pattern adjacent to the plate's surface predicted by previous studies.