BURNING RATE AND PRESSURE DEFLAGRATION LIMIT (PDL) CHARACTERISTICS OF A GAP/AP PROPELLANT SYSTEM

For the application to a mass flux controllable gas generator, GAP is one of the most suitable high energetic materials because of its relatively high pressure exponent. However, its PDL and low pressure burning rate characteristics are not fully investigated yet and it is necessary to know them in detail for such an application. Moreover, a GAP/AP propellant system is considered more feasible because the addition of AP to GAP may be effective to extend the combustible region. Therefore, peculiar attention should be paid to burning rate characteristics of a GAP/AP propellant system. High pressure burning rate of a GAP/AP propellant system has been obtained with a strand burner, and PDL and low pressure burning rates have been investigated by means of a X-ray device as functions of AP content, AP particle size and depressurization rate. The X-ray device is, basically, composed of X-ray source, combustion chamber and X-ray sensor, and the depressurization rate is controllable. The signal at the output of the sensor is sent to a digital acquisition system controlled by PC. Precise calibration between sample length and X-ray signal gives instantaneous sample length during the burning test, thus, instantaneous burning rate taking its time derivative. Therefore, it is possible to obtain low pressure burning rate and PDL simultaneously in one test at a certain depressurization rate. Results of PDL and low pressure burning rate measurements of a GAP/AP propellant system are hereafter presented and discussed.