Application of ultrasonic real-time measurement technology in solid rocket motor

Ultrasonic measurement of burning rate is an advanced technique. For application of ultrasonic measurement in solid rocket motor test, some typical materials used in solid rocket motor (SRM) are measured by ultrasonic technique, and their ultrasonic signal signatures were obtained. The real-time thickness variation of solid propellant at ordinary pressure is measured by an ultrasonic transducer mounted on the outside of the motor shell. A data processing method is proposed to manipulate the echo wave for real-time measurement of burning rate. The proposed method was successfully used in a hot fire test in which the propellant burns at ordinary pressure. The variation in thickness of propellant and its burning rate at ordinary pressure was obtained. The influence of temperature distribution near burning surface on burning rate test is analyzed. The results show that for motor with metal shell, a window must be made on the metal shell to let enough ultrasonic wave energy penetrate the interface between shell and isolator, and for composite shell motor the probe can be mounted outside the shell directly. The influence of temperature variation near burning face caused by combustion on measurement is negligible. The proposed data processing method can be used effectively to obtain the variation of grain thickness. © 2016, Editorial Board of Acta Armamentarii. All right reserved.