固体火箭发动机羽流辐射光谱测温方法研究

固体火箭发动机羽流具有高温、高速与强辐射特征，羽流温度是发动机工作状态与性能的重要表征参数。准确测量固体火箭发动机羽流温度对了解发动机内部燃烧情况以及发动机综合性能具有重要的参考价值。随着激光与光谱学的发展，激光光谱技术逐步应用于固体推进剂燃烧及发动机羽流温度测量。辐射光谱测温法通过测量火焰辐射光谱来实现温度的非接触在线测量，具有测温范围宽、响应快及可靠性高等优点，可应用于固体火箭发动机羽流温度测量。在此提出了基于火焰辐射光谱的固体火箭发动机羽流温度测量方法，采用350～1 000 nm波段光纤光谱仪搭建了发动机羽流火焰辐射光谱测量系统，利用标准辐射黑体炉开展光谱仪响应系数标定，获得响应系数随波长的变化曲线，并以此用作羽流辐射光谱数据修正。之后将该测量系统应用于标准Φ118固体火箭发动机地面试验，开展典型12%铝质量含量推进剂发动机羽流辐射光谱实验测量，选取不同时刻羽流辐射光谱分析了发动机羽流辐射光谱特征，并利用双色法灰性判断原理对羽流火焰灰体特性进行讨论，验证在675～745 nm波段发动机羽流火焰辐射可近似认为灰体，该波段辐射率随波长变化最大相对偏差为4.01%，相对均方差为1.53%。因此，基于普朗克辐射定律开展辐射光谱拟合参数获得不同时刻羽流温度与辐射率参数，并讨论测量结果与发动机工作状态的关系。最后，开展12%，15%与19%铝质量含量的不同推进剂配方固体火箭发动机羽流辐射光谱测量，将辐射光谱法温度测量值与理论热力计算值进行比较，两者最大偏差值为5.40%，讨论了不同铝含量推进剂发动机羽流辐射光谱特征，并结合温度与辐射率测量结果，分析了固体推进剂铝含量对辐射光谱、羽流温度及辐射率的影响。通过固体火箭发动机羽流辐射光谱测温方法研究，为固体火箭发动机性能评估及推进剂配方优化等研究提供了有效的羽流参数测量手段。分析获得的推进剂铝含量对发动机羽流辐射光谱、温度及辐射率参数的影响，为降低固体发动机羽流特征信号提供了重要的实验数据支撑。

Research on Radiation Spectroscopy Thermometry of Plume of Solid Rocket Motor

The plume of solid rocket motor has the characteristics of high temperature, high speed and intense radiation. The temperature of the plume is an essential parameter of condition and performance.The accurate temperature measurement of the plume of a solid rocket motor is important to provide a valuable reference for understanding the internal combustion condition and the overall performance of the motor. With the development of laser and spectroscopy, the laser spectroscopy technology is gradually applied to the measurement of combustion of solid propellant and plume temperature. Radiation spectroscopy thermometry can realize the non-intrusive and on-line measurement of temperature by measuring the radiation spectrum of flame. It has the advantages of wide temperature measuring range, fast response and high reliability. It can be applied to measure the temperature of the plume of the solid rocket motor. In this paper, the thermometry based on radiation spectroscopy was proposed to measure the temperature of the plume of the solid rocket motor. The measurement system of the radiation spectrum of the plume of the solid rocket motor was built using a 350～1 000 nm fiber spectrometer. Moreover, the spectral response coefficient was calibrated with a standard radiation blackbody furnace. The curve of response coefficient with wavelength was obtained to revise the measured radiation spectrums of the plume. Then the measurement system was applied to ground tests of standard Φ118 solid rocket motors, the radiation spectrums of the plume of the solid rocket motor, which with a typical 12% aluminum mass content propellant, were measured. The characteristics of radiation spectrums at different working times were analyzed. Furthermore, the graybody assumption was discussed based on the two-color gray judgment principle. The radiation of plume in a 675～745 nm spectral range can be considered as graybody.The maximum relative deviation of emissivity with wavelength was 4.01%, and the corresponding mean-variance was 1.53%. Therefore, the parameters of temperature and emissivity at the different working times were obtained by spectral fitting based on Planck radiation law. The maximum deviation between the temperature measurement and the theoretical thermodynamic calculation is 5.40%. Besides,the relationship between the measurement results and conditions were discussed, the radiation spectrums of the plume of the solid rocket motors with 12%, 15%, and 19% aluminum mass content propellants were measured, and the characteristics of radiation spectrums with different aluminum mass content were discussed. In addition, the influences of aluminum mass content on radiation spectrums, temperature, and emissivity of the plume were analyzed with the measurement results. This research on radiation spectroscopy thermometry of the plume of the solid rocket motor can provide the tool for performance evaluation and formulation optimization of the solid rocket motor. The influences of aluminum mass content of propellant on radiation spectrums, temperature, and emissivity of the plume can provide the experimental data support for reducing the characteristic signal of the plume of the solid rocket motor.