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Transient Modeling of Hybrid Rocket Low Frequency InstabilitiesA comprehensive dynamic model of a hybrid rocket has been developed in order to understand and predict the transient behavior including instabilities. A linearized version of the transient model predicted the low-frequency chamber pressure oscillations that are commonly observed in hybrids. The source of the instabilities is based on a complex coupling of thermal transients in the solid fuel, wall heat transfer blocking due to fuel regression rate and the transients in the boundary layer that forms on the fuel surface. The oscillation frequencies predicted by the linearized theory are in very good agreement with 43 motor test results obtained from the hybrid propulsion literature. The motor test results used in the comparison cover a very wide spectrum of parameters including: 1) four separate research and development programs, 2) three different oxidizers (LOX, GOX, N2O), 3) a wide range of motor dimensions (i.e. from 5 inch diameter to 72 inch diameter) and operating conditions and 4) several fuel formulations. A simple universal scaling formula for the frequency of the primary oscillation mode is suggested.
Document ID
20040139910
Document Type
Conference Paper
Authors
Karabeyoglu, M. Arif (Stanford Univ.)
DeZilwa, Shane (NASA Ames Research Center Moffett Field, CA, United States)
Cantwell, Brian (Stanford Univ.)
Zilliac, Greg (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2003
Subject Category
Spacecraft Design, Testing and Performance
Report/Patent Number
AIAA Paper 2003-4463
Funding Number(s)
CONTRACT_GRANT: NCC2-1172
CONTRACT_GRANT: NAG3-2884
CONTRACT_GRANT: NAG3-2615
CONTRACT_GRANT: NCC2-1300
Distribution Limits
Public
Copyright
Public Use Permitted.

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