Measurement and validation of nitrogen radiative intensity in shock tube
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摘要: 超高速飞行器的热防护设计必须考虑激波层内高温气体发射与吸收的辐射能量，需要有效的辐射加热评估手段。相应飞行条件下的光谱辐射强度地面实验测量是验证数值模型和方法、理解高焓流动的重要手段。基于燃烧驱动激波管，发展辐射强度标定技术，针对富氮气环境，开展高温气体光谱辐射强度的高分辨定量化测试，掌握辐射特征，为数值验证提供基础数据。实验获得了激波速度5.70和6.20km/s条件下的气体光谱辐射强度精细结构，数据表明激波波后的非平衡过程对辐射强度存在很大影响。通过求解耦合化学反应动力学模型的Navier-Stokes方程和辐射特性模型，得到对应实验条件下的流场参数和辐射强度，计算结果和实验数据符合很好，验证了数值模拟方法。Abstract: The radiative energy emitted and absorbed by high temperature gas in the shock layer must be considered in the thermal protection system design of hypervelocity vehicles. Efficient evaluation methods are needed to predict the radiative heat flux. Absolute radiance measurement in ground facilities is an important way to understand the physics of the high enthalpy flow and to improve the numerical models. Radiance calibration techniques have been developed in a combustion-driven shock tube. High resolution spectral radiative intensities have been measured in rich N2 environment to validate the numerical models. Detailed radiance spectral structures have been acquired at shock velocity 5.70 and 6.20km/s. It is found that the non-equilibrium process behind the shock affects the gas radiation remarkably. Numerical simulations under corresponding experimental conditions have been conducted using an in-house built code solving Navier-Stokes equations with chemical reaction models and radiation models. The results show that computational results agree well with experimental data.
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图 2 激波管辐射定量测试实验的原位标定系统和仪器示意图
Figure 2. Schematic diagram of in-situ calibration system for absolute radiation measurement in shock tube
图 3 响应系数和系统偏置的标定结果
Figure 3. Calibration results of response coefficient and system bias
图 4 800Pa、5.70km/s状态的N2辐射强度定量试验结果
Figure 4. Quantized radiance measurement of N2 at 800Pa, 5.70km/s
图 5 激波速度5.66km/s的流场参数计算结果
Figure 5. Computational results of flow parameter at shock velocity 5.66km/s
图 6 6μs延迟的辐射强度计算结果和对比
Figure 6. Comparison of radiance between computation and experiment at 6μs time delay
图 7 6μs延迟不同组分的辐射强度计算结果和对比
Figure 7. Comparison of radiance between computation emitted from different species and experiment
图 8 500Pa、6.20km/s状态的N2辐射强度定量试验结果
Figure 8. Quantized radiance measurement of N2 at 500Pa, 6.20km/s
图 9 激波速度6.20km/s的流场参数计算结果
Figure 9. Computational results of flow parameter at shock velocity 6.20km/s
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