高超声速对流环境下冷点效应对圆箔式热流传感器测热特性的影响研究

在高超声速对流环境测量气动加热时，圆箔式热流传感器表面温度往往低于被测物体表面温度，这种表面温度的不连续会影响边界层流动，使热流测量结果产生偏差。针对高超声速对流条件下的钝头-平板模型，采用数值模拟方法研究了传感器表面局部低温引起的"冷点效应"形成机理以及对表面热流的影响。结果表明:被测物体表面壁焓H_w与恢复焓H_re的比值H_w/H_re越高，"冷点效应"越明显；传感器表面温度T_w2与被测物体表面温度T_w1的比值T_w2/T_w1越小，"冷点效应"越明显；来流雷诺数Re对"冷点效应"影响较小。在马赫数Ma=18的来流条件下，研究分析了冷点效应对传感器测量结果的影响，结果表明:冷点效应使测量结果偏高1.25倍，复现了热流预示结果与试验结果的差异。

Study on the influence of cold spot effect on the thermal measurement characteristics of circular foil heat flow sensor in hypersonic convection environment

When a circular foil heat flux sensor is used to measure aerodynamic heating in a hypersonic convection environment, the surface temperature of the sensor is often lower than the surface temperature of the measured object. This surface temperature discontinuity would affect the flow of the boundary layer, which could distort the heat flux measurement result. For a blunt-head plate model, the numerical simulation method was used to study the formation mechanism of the "cold-spot effect" and the influence of the local low temperature of the sensor surface on the surface heat flux under hypersonic flow conditions. The results show that:the higher H_w/H_re is, which represents the ratio of the surface enthalpy of the measured object to the recovery enthalpy of the flow, the more obvious the "cold-spot effect" is; the lower T_w2/T_w1 is, which represents the ratio of the sensor surface temperature to the measured surface temperature, the more obvious the "cold-spot effect" is; the flow Reynolds number Re has less effect on the cold spot effect. The deviation of measurement results in response to the "cold spot effect" is analyzed under the condition of Mach 18 flow. The results show that the "cold spot effect" can make the measurement result 1.25 times higher, which reproduces the difference between the heat flow prediction results and the test results.