高焓流场球头外形气动热试验研究

Experimental study on aerodynamic heat of sphere heads in high enthalpy flow

再入地球大气层时,飞行器的再入速度极高,面临严重的气动加热问题。为了研究高焓流动导致的热化学非平衡现象,在高焓膨胀风洞FD-14X中开展了球头外形的热流测量试验以及CFD仿真模拟。FD-14X为中国空气动力研究与发展中心新建成的高焓膨胀风洞,速度模拟能力达到第二宇宙速度,总温模拟能力超过10000 K,能够产生总焓70 MJ/kg的试验气体。试验来流总焓16.9~63.5 MJ/kg,球头直径20~50 mm,流场采用自发光拍照,同时CFD仿真采用Park双温非平衡模型计算球头绕流流场。试验与仿真结果表明:来流总焓大于5 MJ/kg时,球头绕流场存在显著的热化学非平衡现象;304钢模型壁面在来流总焓小于20 MJ/kg时表现为非催化壁面特性,在来流总焓大于30 MJ/kg时表现为催化壁面特性;当球头表面镀氧化锆膜、来流总焓49.5 MJ/kg时,球头壁面表现为非催化壁面特性。

Vehicles re-entering the Earth's atmosphere with extremely high re-entry velocities face serious aerodynamic heating problems.In order to investigate the thermochemical non-equilibrium phenomenon caused by high enthalpy flow,heat flux measurement experiments and CFD simulations of the spherical head profile have been carried out in the wind tunnel FD-14X,which is a newly constructed high enthalpy expansion wind tunnel of the China Aerodynamic Research and Development Center(CARDC).It has the ability to generate incoming flow with the second cosmic velocity and the total temperature greater than 10000 K,thus it can produce flows with a total enthalpy up to 70 MJ/kg.In this study,the heat flux measurement on the hemispheres with diameters of 20~50 mm in the flow of a total enthalpy of 16.9~63.5 MJ/kg was carried out,and the flow fields were photographed by self-illumination.CFD simulations of the flow fields around the hemispheres were carried out using the two-temperature non-equilibrium model.The numerical and experimental results show that when the total enthalpy of the incoming flow is greater than 5 MJ/kg,there is a remarkable thermochemical non-equilibrium phenomenon in the flow field around the sphere heads.When the total enthalpy of incoming flow is less than 20 MJ/kg,the wall surface of the 304 steel model shows the noncatalytic characteristic;when the total enthalpy of the incoming flow is greater than 30 MJ/kg,the wall surface of the 304 steel model shows the catalytic characteristic.When the hemisphere surface is coated with a zirconia film and the total enthalpy of the incoming flow is 49.5 MJ/kg,the surface of the model shows the characteristics of a noncatalytic wall.