Study On The Influence Of Wall Temperature On Thermal Environment Of Several Typical Hypersonic Vehicles

With the continuous development of hypersonic vehicle,its shape is more and more complex,the flight Mach number is increasing,the flight time is longer and longer,resulting in the increasing aerodynamic heating,which puts forward higher requirements for the current thermal environment prediction accuracy.However,in the long flight process,the aerodynamic heating at different positions of the aircraft is not uniform,which leads to the further difference between the temperature distribution and the initial wall temperature,which puts forward new requirements on how to consider the influence of the wall temperature on the thermal environment in the future hypersonic vehicle design process.Aiming at the influence of wall temperature on the thermal environment of hypersonic vehicle,the typical structures such as ball head,compressed corner,blunt rudder with gap are selected in this paper.The software independently developed by the research group is used to solve the Navier Stokes equation of viscous compressibility based on the finite volume method.Some conclusions are obtained,including the following aspects:The wall temperature has little effect on the flow field structure of the ball head,the wall temperature increases,the density near the wall decreases,the viscosity coefficient increases,the heat flux around the ball head decreases gradually,and the dimensionless heat flux changes little.The hot wall correction formula has a good correction effect on the ball head,which meets the practical application needs.With the increase of the wall temperature,the overall structure of the compression corner flow field has little change.However,due to the large change of the physical parameters of the fluid near the wall,the separation point of the corner separation vortex moves forward,and then the attachment point moves backward,and the interference area at the corner expands.The heat flux in most areas of the compression corner decreases with the increase of the wall temperature,and the heat flux in the interference area decreases more than that in the non interference area.In addition,by comparing the heat flux calculated by the variable wall temperature and the heat flux corrected by the hot wall correction formula,it is found that the accuracy of the hot wall correction formula in the interference area is reduced and the applicability is insufficient.When the wall temperature increases,the overall structure of the separation vortex around the blunt rudder changes little,but its size increases,which changes the location and distribution of separation streamline and reattachment streamline around the blunt rudder,and the interference area of the blunt rudder expands;at the same time,the interior of the gap is gradually "blocked" and the transverse separation reattachment weakens.The heat flux in most areas of the blunt rudder decreases with the increase of the wall temperature,and the heat flux in the gap and the rudder shaft decreases more,but the heat flux in some areas of the interference area increases with the increase of the wall temperature.In addition,by comparing the heat flux calculated by the variable wall temperature and the heat flux corrected by the hot wall correction formula,it is found that the direct use of the hot wall correction formula in the interference area around the blunt rudder also has the problems of local accuracy reduction and applicability shortage.The results of coupled calculation for blunt rudder show that the heat flux at the local position of rudder shaft is lower than that obtained by traditional calculation method in real situation,and the temperature level obtained by bidirectional coupling calculation is lower than that by unidirectional coupling calculation in aerodynamic heat / heat transfer calculation.The study of this paper further deepens the understanding of the influence of wall temperature on the flow of ball head,compression corner,blunt rudder with gap and other typical structures,and has reference significance for the applicability of the hot wall correction formula in these models.