Research On Measurement Method Of Propellant Combustion Temperature Based On Two-color Planar Laser-induced Fluorescence

Propellant is an important part of rocket launch.It is of great guiding significance to study the gas composition,temperature and sufficient combustion conditions in the combustion process of propellant,which are also the basis of efficient and orderly combustion of propellant.In the combustion field diagnosis technology,temperature is one of the important parameters to study the combustion mechanism.Qualitative or quantitative study of two-dimensional temperature field distribution in propellant combustion process has important guiding significance for in-depth understanding of flame combustion morphology,flame combustion composition detection,combustion surface preparation.Two-dimensional temperature of alcohol lamp and propellant combustion flame will be measured by two-color plane laser-induced fluorescence temperature measurement technology.Two-color planar laser-induced fluorescence temperature measurement system is designed,and the modules of the temperature measurement system are summarized.Before setting up the chip light shaping module,the chip light simulation and simulation are carried out and the actual focal length of each cylindrical mirror is obtained,tested the gain of the camera equipment in the fluorescence detection module,provided the timing system of the system and detect the energy of the laser output by the laser module,a temperature calibration system is designed to measure the combustion flame temperature of alcohol lamp and propellant.The experiment of two-dimensional temperature measurement of alcohol lamp flame is carried out.Before the experiment,the drift of the laser output wavelength is observed and the excitation spectrum line to excite the OH in the combustion flame of the alcohol lamp is set,and the fluorescence image of the corresponding wavelength is collected.The temperature calibration system is used to measure the outer flame,inner flame and flame core temperature of alcohol lamp.The measurement results are 851.7±1.5K,775.6±1.3K and 679.7±0.9K.According to the fluorescence image and temperature measurement results,the two-dimensional temperature field distribution image is calculated and inversed.The results show that the relative errors of the average temperature,outer flame temperature,inner flame temperature and flame core temperature of the two-dimensional temperature field distribution image obtained by the combination of Q₁（10）/P₁（7）and Q₂（11）/P₁（7）are less than 4%compared with the calibration temperature,which verifies the feasibility of the two-color plane laser-induced fluorescence temperature measurement method.Finally,the experiment of two-dimensional temperature measurement of propellant flame is carried out.Before the experiment,the propellant ignition experiment and temperature calibration experiment are carried out.The temperatures of propellant samples are 675.2±2.0K,710.2±2.5K and 771.5±3.5K.The original fluorescence image of propellant flame and the inversion calculation of two-dimensional temperature field image of flame are obtained.Then the temperature results of thermocouple calibration are compared with the two-dimensional temperature field distribution image.The results show that the relative errors of two-dimensional temperature field distribution images of sample 1 excited by Q₂（11）/P₁（7）combination and sample 2 excited by Q₁（10）/P₁（7）and Q₂（11）/P₁（7）combination are 1.08%,0.98%and 0.80%respectively.Therefore,Q₂（11）and P₁（7）are the best spectral lines for measuring the combustion flame temperature of alcohol lamp and propellant.