ACOUSTIC LOSSES OF A SUBSCALE, COLD-FLOW ROCKET MOTOR FOR VARIOUS 'J' VALUES
- 1 February 1966
- report
- Published by Defense Technical Information Center (DTIC)
Abstract
Acoustic dissipation studies were undertaken using a subscale, cold- flow rocket motor model to determine the effect of purely geometric variables on the acoustic performance leading to axial mode combustion instability. Cold air served as the working fluid to simulate the internal flow and to obtain a critical nozzle throat condition. Using interchangeable metal parts, it was possible to simulate the geometry of a cylindrical-bore grain at various real motor burn times and also to vary the nozzle throat diameter. The results confirmed the speculation that, for practical motor designs, the radiation of acoustic energy through the nozzle is the largest source of loss for the axial mode and increases with the J of the motor. In view of the change in J with time during burning, this loss can vary conspicuously during the motor burn time.Keywords
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