Research on Emission Spectrum Temperature Measurement Methods of Boron-Based Fuel Flames

Boron (B) has the advantages of high gravimetric oxidation heat value, high volumetric oxidation heat value, and clean combustion products, making it an ideal metal fuel to improve the specific impulse of the solid motor. In this paper, the emission spectrum temperature measurement experiment was carried out, based on BO₂, which is an important intermediate product of boron-based fuel combustion flame. Through molecular spectrum theory research, the energy composition of BO₂ molecular spectrum was analyzed, and the theoretical spectral model of the A-X transition band of BO₂ molecule was established, utilizing molecular spectral constants and spectral fitting software. The temperature sensitivity of the theoretical spectral model was studied under different temperature and band broadening parameters. In addition, this paper also preprocessed the data of the experimental spectrum and realized the fitting of the theoretical spectrum and the experimental spectrum through the least squares method, thereby retrieving the gas phase temperature of the combustion flame under different experimental conditions. It has proved that the temperature measurement method based on BO₂ molecular emission spectrum is a feasible approach under the conditions of complex combustion flame of boron-based fuel.