高超声速再入试验的辐射光谱定量测量

利用膨胀管对宽度为45 mm和90 mm的半圆柱模型进行了地球再入高超声速流动试验,再入速度为8 km/s。试验利用配有ICCD相机的光谱仪,测量了具有空间分辨的激波后辐射光谱,光谱范围为250~550 nm,得到了沿流体方向的激波辐射轮廓线。分析发现在该光谱范围内辐射主要为CN(B-X)带系分子光谱。利用卤钨灯对该波段光谱进行定标,得到了激波层辐射的绝对辐射亮度。通过采用两种模型辐射亮度对模型宽度归一化后发现,绕流场高温气体辐射存在较强的自吸收现象,同时观测到了绕流场激波的三维效应。通过实验发现,CN(B-X)Δv=0带系的3-3振动带系385.2 nm波长位置和0-0带系388.4 nm波长位置辐亮度之比随着流场靠近模型边缘而逐渐下降,这表明激波层内辐射的动态非平衡特征。

Measurements of absolute radiative emissions for supersonic reentry

An expansion tube facility was operated using two half-cylinder models with width of 45 mm and 90 mm respectively for producing high-enthalpy flows at the nominal velocity of 8 km/s relevant to Earth reentry.Spatially resolved emission spectroscopy in the wavelength range from 250 nm to 550 nm behind a shock wave was recorded by a spectrometer with ICCD camera.Shock wave stagnation streamline was observed along the flow direction.It is found that the spectrum are dominated by the CN(B-X)violet band.A halogen tungsten lamp was used to realize calibration and the absolute radiation luminance of the shock layer was obtained.By comparing the model widths normalized by two kinds of model radiances,it can be found that there is a strong self-absorption of high temperature gas radiation around the flow fluid.In addition,three-dimensional effect was observed.It can be found that the ratio between spectral radiance at 385.2 nm in the CN(B-X)violet 3-3 band and spectral radiance at 388.4 nm in the CN(B-X)violet 0-0 band is decreasing along the distance toward the model edge.The results illuminated that dynamical non-equilibrium features exists in the shock layer along the distance of the model edge.