Numerical Rebuilding And Mechanism Analysis Of Shock/Boundary-layer Interaction In High-Enthalpy Tunnel

In this paper,JF-10 hydrogen-oxygen detonatiom-driven high enthalpy shock tunnel in the Institute of Mechanics of the Chinese Academy of Science is taken as the object of study to carry out the numerical rebuilding and mechanism analysis of shock/boundary-layer interaction in high-enthalpy tunnel.The nozzle flow-fields and the test model flow-fields in the test section flow-fields of the high-enthalpy shock tunnel are calculated sequentially,and the non-equilibrium effects are investigated.First,operational states in the total temperature range of 4000?10000K,total pressure range of 10?99MPa and total enthalpy range of 5.3?27MJ/kg are selected to carry out nozzle flow-field simulation.The effects of raising total pressure to suppress the thermochemical freezing in the nozzle are analyzed.The freestream parameters over wide range of speed and density are prepared for the subsequent analysis of freestream non-equilibrium on the flow with shock/boundary-layer interaction.Before carrying out the test segment model flow-field calculation,the compression corner is taken as an example to analyze the influence of grid resolution in the direction of flow on capture of flow field structure.The ratio of flow grid scale to local boundary thickness is proposed as the flow grid criterion parameter.Then the numerical simulation and analysis of compression corner flow and double wedge flow under multiple tunnel operating conditions are carried out,and the effect of non-equilibrium of free-stream in in high-enthalpy tunnel on flow is studied by comparing the flow-fields under the equilibrium free-stream and non-equilibrium free-stream of the same total enthalpy or the same speed.The results showed that the flow-field structure and wall characteristic of non-equilibrium free-stream and equilibrium free-stream which has the same velocity and Mach number are consistent under conditions of no separation or little separation.For a compression corner flow and double wedge flow with a strong separation,even if the same speed and Mach number are maintained,the non-equilibrium of the free-stream will significantly promote separation.This shows that for flow with shock-wave boundary-layer interaction and complex flow wave structure,the effect of free-stream thermochemical state is greater than that of bluff body.In this type of flow,the effect of velocity or Mach number under the condition of the same total enthalpy increases.This paper also expands the research group's non-equilibrium flow-field calculation program to realize 3D multi-block grid parallezation calculation.Through the numerical simulation of the three-dimensional compression corner and three-dimension double wedge flow with finite extension,then variation of the flow along the direction of the flow and the difference between the three-dimensional and two-dimensional flow structure are analyzed,and the influence of the three-dimensional effect is investigated.The results showed that there is no significant difference between the central symmetry plane and the two-dimensional flow-field,but after leaving central symmetry plane,the shock intensity decrease,and the shock wave detachment distance and the length of the separation area gradually decrease.The pressure drops sharply near the side edge of the model,and the high pressure gas above the model expands towards the side edge zone,producing a series of expansion waves.The numerical simulation and analysis of the high enthalpy tunnel nozzle and shock /boundary-layer interaction flow in high enthalpy tunnel will provide a reference for the detailed understanding of the flow-field characteristic of high enthalpy tunnel and the effective implementation of the non-equilibrium experiments.