Accession Number:

AD0618818

Title:

NONLINEAR AXIAL COMBUSTION INSTABILITY IN SOLID PROPELLANT MOTORS,

Descriptive Note:

Corporate Author:

CANADIAN ARMAMENT RESEARCH AND DEVELOPMENT ESTABLISHMENT VALCARTIER (QUEBEC)

Personal Author(s):

Report Date:

1963-11-20

Pagination or Media Count:

10.0

Abstract:

Nonlinear axial combustion instability occurs when one or more strong gaseous compression waves propagate longitudinally within a solid propellant rocket motor. The nonlinear unsteady flow field derives energy through interaction with the combustion process and causes an increase in the time-averaged burning rate, pressure, and thrust. This behavior has been investigated using polyurethane-ammonium perchlorate propellanta and some 200 motors in the size range 2-in.-diam by 10-in.-long to 17-in.-diam by 180-in.long. Reproducible results were obtained. The motors were found to be linearly stable and nonlinearly unstable with respect to initiation of instability. Thus, normal proof firings are unlikely to detect inherent instability, since a flow disturbance of finite amplitude is required to trigger the system. A pulse injection method of triggering was applied to all firings. As operating pressures increased above a critical value P the motors became capable of instability, the severity increasing monotonically with the restriction ratio. The effect on the critical value of changing the motor scale, length to diameter ratio, grain cross section, grain temperature, and of adding aluminum alloy and lithium fluoride to the propellant was determined. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE