Temperature Measurement Of Solid Rocket Unstable Combustion Based On Ultrasonic Sensor

With the rapid development of China’s aviation industry,there are higher requirements for the indicators and performance of the aviation solid rocket motor.As a very keyparameter in the working process of the aviation solid rocket motor,whether thetemperature of the combustion chamber and plume of the solid rocket motor can be measured very accurately,It will directly affect the design and manufacturing process of solid rocket motor.The temperature of the engine exhaust can reach 1300 ℃,and the temperature of the combustion chamber can even reach more than 3000 ℃.Therefore,many traditional temperature sensors,such as thermocouple sensor(whose temperature range can only reach1800 ℃),compared with the high temperature of 3000 ℃ in the combustion chamber,obviously can not meet the requirements,and can not measure the temperature of the engine combustion chamber.Although there is no theoretical upper range limit for radiation thermometry,it is an indispensable link in the process of material emissivity modification,so it also makes the difficulty of dealing with the results of radiation thermometry to a certainextent.In addition,the stage of using the radiation temperature will also be greatly different because of the role of the intermediate medium.Combined with the engineering practice,in the industrial site environment,the environment is obviously poor,and the final measurement results will be more affected by the intermediate medium,so the final accuracy can not be maintained at a high level.In this paper,a temperature sensor is designed and manufactured by using ultrasonic temperature measurement technology.Iridium rhodium alloy is selected as the sensor material.The diameter of the sensor and the diameter of the reflection groove are determined,and the length of the reflection section is determined.The sensitivity is0.005 ? / ℃ and the repeatability is 98% under 95 confidence interval.After several sensor calibration,the following results are obtained: at the same temperature,the temperature error of platinum rhodium thermocouple and sensor is within 0.5 percentage point,and the absolute value of mean square error in the whole range is 5 ℃.Through the experiment,it is found that the sensor has the feature of small error,which is convenient to repeat.Then,the finite element simulation of solid rocket motor plume temperature distribution is carried out by using FLUENT software,and the plume temperature test is carried out on the test platform,and the results are compared.Finally,the acoustic modal analysis of the combustor cavity is carried out,and the analysis results are consistent with the theoretical analysis,which fully verifies the accuracy of the numerical simulation.The working process of solid rocket motor combustor is simulated by finite element method.Four assumptions are made for the working process of combustor.The numerical simulation results show that when the internal combustion chamber of solid rocket motor reaches a stable state,the internal temperature exceeds 3000 ℃.