Aerodynamic Design Of Multi-Mach Numbers Platform Based On Hypersonic Ludwieg Tube

Hypersonic Flight Vehicle(HFV)has great significance for national military construction.The development of HFV depends largely on many basic scientific issues,such as the transition of the boundary layer.By predicting and controlling the transition of the boundary layer effectively,the fuel consumption can be greatly reduced and the payload of high-speed aircraft can be significantly increased.At present,the wind tunnel experiment is still the mainstay of hypersonic boundary layer transition research.However,due to the problems of noise radiation from turbulent boundary layer on the nozzle wall and other issues,the boundary layer transition data obtained in existing hypersonic wind tunnels are still quite different from that obtained in real situations.Combining with the actual needs and the experience of building experimental research platforms at home and abroad,this paper carried out the aerodynamic design of the multi-Mach number platform based on the hypersonic Ludwieg tube wind tunnel.In order to realize the multi-Mach number operation mode and high flow field quality of the experimental platform,the tandem nozzle Ludwieg tube wind tunnel aerodynamic layout was used in this article.First,the Mach 5 conventional Ludwieg tube wind tunnel design was completed based on the principle of the Ludwieg tube wind tunnel,focusing on numerical optimization of the fast-acting valve and the Mach 5 Laval nozzle.Then,based on the platform of the Mach 5 conventional Ludwieg tube wind tunnel,an additional Laval nozzle and settling chamber were added,and the second Laval nozzle was redesigned to obtain the flows of Mach 3 and Mach 6,respectively.This part of the work focuses on the numerical optimization of the combination of the first throat and the settling chamber,and the design criteria of the stabilization section under different throat area ratios were explored.The results showed that,based on the conventional Ludwieg tube hypersonic wind tunnel the velocity domains lower and higher than the original Ludwieg tube hypersonic wind tunnel could be obtained respectively by changing the throat blockage area.For the extension to larger Mach range,the quality of the flow field was increased after using the appropriate settling chamber.For the case of extension to the low Mach range,the flow in the settling chamber was more complicated.Flow stabilizing methods were used in this article to improve the quality of the flow field.This article explored the feasibility of the method for expanding the speed range of the Ludwieg tube tunnel,which provided a reference for the application of the Ludwieg tube wind tunnel in basic experimental research.