An Investigation of Flow Separation in an Overexpanded Supersonic Nozzle

Citation

McKenney, John Dill (1949) An Investigation of Flow Separation in an Overexpanded Supersonic Nozzle. Engineer's thesis, California Institute of Technology. doi:10.7907/G1V3-A479. https://resolver.caltech.edu/CaltechETD:etd-02272009-143254

Abstract

An apparatus for the investigation of flow separation in a supersonic nozzle has been designed and constructed. Nozzle wall pressure distributions and shadowgraphs showing the associated shock wave configuration have been obtained for a range of different stagnation pressures and constant exit pressure.

The pressure ratios were such that the theoretical nozzle exit pressure, without separation, was always less than atmospheric pressure. With the nozzle contour and pressure ratios investigated it is found that separation of flow from the nozzle walls always occurs. The separation is accompanied by a weak oblique shock wave of such strength that the flow deflection through it is approximately constant, independent of the location of the point of separation within the nozzle. The pressure adjustment from nozzle to exit does not occur through a normal shock wave.

At pressure ratios below a certain value a definite asymmetry of flow appears in which the detached jet deflects away from the nozzle symmetry axis. At higher pressure ratios, the flow becomes stable with separation occurring at the same distance from the nozzle throat on both upper and lower walls.

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