Design of an Axisymmetric, Contoured Nozzle for the HEG.

Abstract

An axisymmetric, contoured nozzle is designed for the High Enthalpy Wind Tunnel Goettingen (HEG). In the conical part of the expansion the flow is calculated using a quasi one-dimensional approximation, taking into account finite rate chemical kinetics. Assuming a source flow and species freezing at the end of the conical section, the contoured part of the nozzle contour is subsequently determined using the method of characteristics for a perfect gas. The physical nozzle contour is f inally obtained by adding the boundary layer displacement thickness, calculated by using an empirical correlation, to the inviscid contour. In addition to the discussion of the performance at off-design conditions, different chemical models and rate constants are used in the quasi one-dimensional calculations in order to investigate the influence on the flow properties.