Improvements in the measurement of hybrid rocket fuel regression rate using ultrasonic transducers

Abstract

Presented are the improvements to an ultrasonic transducer measurement system capable of measuring fuel regression as a function of motor burn time and port location. The measurement technique involved the use of an Ultrasonic Transducer System (UTS) composed of sixteen ultrasonic transducer assemblies, two multiplexers (pulser/receiver), and a data collection/reduction system. Fuel regression rate data is computed from the UTS detected web thicknesses. During sub-scale motor operation, web thicknesses at up to 8 stations in the motor were measured incorporating buffer and instrumentation amplifiers and a low-pass filter. Ultimately, the ultrasonic transducer system improvements will allow reliable measurements at 16 stations in a 250 KIbf hybrid motor to be tested beginning in September 1997 and running through 1999.