Design and Analysis of Cooling System for Hypersonic Wind Tunnel Nozzle

Abstract

Heat transfer analysis of throat section of hypersonic nozzle, of the wind tunnel system which will be used to test Hypersonic Technology Demonstrator Vehicle (HSTDV) is carried out in this research work. Attention is focused on the heat transfer inside nozzle, where high energetic flows have to be controlled for ensuring the safe operation of the nozzle. Solution for the problem is investigated by means of two correlations and CFD based numerical solution. Based on comparison between empirical results and CFD results conclusion was derived about appropriate method to estimate heat flux through nozzle wall. For designing the cooling system, estimation of heat flux through nozzle wall is needed. The CFD analysis was carried out for given mach number for flow of air through convergent-divergent nozzle using commercial software. The analysis was carried out by altering grid to verify solution’s independency of grid and using three turbulence model to reach proper heat flux value. Parametric analysis was done at different inlet pressure and temperature condition. Computational procedure is more costly as it require software and computational time also. On other side analytical procedures to determine heat flux using empirical correlations are easier but limited for thermal design of aerodynamics heating in nozzle. Before using empirical correlation on regular basis to predict heat flux at wall, it is required to ensure validity of result obtained by it. In this project work, Eckert and Bartz empirical methods were compared with CFD numerical solution. Bartz method gives good agreement with numerical solution. Generated heat should be extracted by employing cooling system for safe operation in the hypersonic nozzle. Results for heat flux and outside water temperature for flat plate are compared. To estimate cooling parameters using CFD analysis, heat flux value is incorporated based from empirical correlation and wall at throat of nozzle is approximated as a simplified geometry (flat plate). In this way it is possible to make simulation computationally less expensive by incorporating heat flux from empirical correlation in simplified CFD analysis and distribution of wall temperature and water temperature can be estimated.