Mary Fran. Desrochers, Gary W. Olsen, Chris Luchini, and M. Keith Hudson
ABSTRACT: The development of the hybrid rocket motor has been plagued by combustion instabilities. These are usually monitored as fluctuations in chamber pressure and are on the order of tens of Hz in frequency. Previous work using our labscale hybrid system has also indicated instabilities at these frequencies. These have been attributed to fuel chuffing or other phenomena. Additional studies, in areas such as IR and other spectral monitoring, have indicated that these oscillations are also present in the plume as light emission flicker. However, they were not investigated in the previous work. This paper presents a study of these specific phenomena and attempts to correlate plume flicker, acoustic data, and higher speed chamber pressure monitoring. It was found that the plume flicker frequencies match those found using high speed pressure transducers, although these light intensity fluctuations demonstrate greater amplitude. Acoustic data could not be correlated, as it appears as a form of white noise. The authors feel that flicker data offers an inexpensive but sensitive alternative to high-speed pressure transducer use.
Keywords: hybrid rocket, exhaust plume, plume diagnostics, combustion diagnostics, engine health monitoring, optical emissions, acoustic emissions
Ref: JPyro, Issue 13, 2001, pp35-39
(J13_35)
© Journal of Pyrotechnics and CarnDu Ltd
