0.6m Shock Tunnel Mach 8 Nozzle Design And CFD Simulation

Shock tunnel is one kind of important test facilities used in hypersonic aerodynamic researches, especially in the experimental investigations in high Mach number and high Reynolds number flows. One of the most important components of the shock tunnel, the hypersonic nozzle which generates hypersonic uniform flow, has a crucial influence on the flow quality.In this dissertation, with the background of the experiment platform reconstruction for the 0.6m shock tunnel, a Mach 8 nozzle was designed with the classical mothod of characteristics and calibrated with modern CFD tools. The main achievements in this work are as below:(1) The nozzle wall contour for exit flow of Mach number 8 was designed based on the method of characteristics and the technique of boundary layer correction. The gas imperfection induced by high pressure and high temperature was concerned in the nozzle design process which related to the Sivells method. Edenfield method was chosen to calculate the displacement boundary layer thickness which was used to correct the nozzle inviscid wall contour. And the Witoszynski formula was adopt to obtain the contraction curve of the nozzle’s subsonic section. A computer programe in FORTRAN was compiled for the whole design approach.(2) CFD tools were used to qualify the flow quality in the designed Mach 8 nozzle. Verification for the CFD method, including gas models and turbulent models, was performed by comparing the CFD result with the experiment calibration data under similar nozzle operation. The CFD results indicated that the flow quality of the designed nozzle was satisfactory and was much better than the requirement of the criterion for shock tunnel test flows.(3) The study on the effects of the nozzle wall imperfections on the flow quality was performed through CFD simulation. According to the real situation, two kinds of wall imperfections were included. One is the step occurring at the joint between the throat section and the downstream nozzle section. The other one is the small pit at the joint between the nozzle expansion sections. The CFD results revealed that the steps always induced obvious disturbance on the nozzle flow and this kind of wall imperfection must be carefully controlled in real situation. While the small pit between nozzle sections has only limited influence on the local flow uniformities and has no obvious adverse effects on the nozzle exit flow quality.