Investigation of the Characteristics of the Velocity-Coupled Response Functions of Solid Propellants,
GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
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This paper describes the results of an experimental investigation which has been concerned with the validity of state-of-the-art approaches which use the so-called velocity-coupled response functions to determine the stability of solid propellant rocket motors. These approaches are based upon the fundamental assumption that the propellant velocity-coupled response function is a propellant property which is independent of location within the combustor. The validity of this assumption was investigated in a modified impedance tube setup specifically developed for this study. It consisted a driver propellant sample at the upstream end of the tube and test propellant samples on the side walls at a desired location downstream of the driver propellant. An acoustic driver located at the downstream end of the tube was used to simulate conditions in an instable motor by exciting a standing acoustic wave of desired properties in the tube. During a test, the driver was turned on, all the propellant samples were ignited and a series of pressure transducers attached to the tube wall was used to measure the resulting standing wave structure. These data together with a specially developed data reduction program were used to determine the velocity-coupled response functions of the test propellant samples.