3-D shock structure in underexpanded supersonic jets from elliptical and rectangular exits

Abstract

The complex shock structure within underexpanded supersonic jets issuing from rectangular (Aspect ratios of 1 and 2) and elliptical (ratio between major and minor axes of 2 and 4) nozzles have been analysed numerically. The simulations were performed using the commercially available Navier-Stokes code CFX 5.5.1©. The flow field in the jet from an elliptical nozzle contains a complex series of 3-dimensional shock interactions. The shape of the incident barrel shock is different when viewed across the major and the minor axes of the elliptic nozzle. In the case of a rectangular nozzle the flow along the planes perpendicular to the flat sides of the nozzle resemble a planar nozzle flow field, with a series of expansion waves originating at the nozzle lip and reflecting back from the jet boundary as compression waves. The flow field along the diagonal plane contains a shock wave originating from the corners of the nozzle.