Time-Frequency Analysis of Rocket Nozzle Wall Pressures during Start-up Transients

Baars, W, Tinney, C and Ruf, J 2011, 'Time-Frequency Analysis of Rocket Nozzle Wall Pressures during Start-up Transients', in Konrad Bajer; Jacek Kopeć; Miron Kursa; Kamil Kwiatkowski and Piotr Podziemski (ed.) Proceedings of the 13th European Turbulence Conference (ETC13), Warsaw, Poland, 12-15 September 2011, pp. 2464-2473.


Document type: Conference Paper
Collection: Conference Papers

Title Time-Frequency Analysis of Rocket Nozzle Wall Pressures during Start-up Transients
Author(s) Baars, W
Tinney, C
Ruf, J
Year 2011
Conference name ETC13
Conference location Warsaw, Poland
Conference dates 12-15 September 2011
Proceedings title Proceedings of the 13th European Turbulence Conference (ETC13)
Editor(s) Konrad Bajer; Jacek Kopeć; Miron Kursa; Kamil Kwiatkowski and Piotr Podziemski
Publisher Institute of Physics Publishing
Place of publication Bristol, United Kingdom
Start page 2464
End page 2473
Total pages 10
Abstract Surveys of the fluctuating wall pressure were conducted on a sub-scale, thrust- optimized parabolic nozzle in order to develop a physical intuition for its Fourier-azimuthal mode behavior during fixed and transient start-up conditions. These unsteady signatures are driven by shock wave turbulent boundary layer interactions which depend on the nozzle pressure ratio and nozzle geometry. The focus however, is on the degree of similarity between the spectral footprints of these modes obtained from transient start-ups as opposed to a sequence of fixed nozzle pressure ratio conditions. For the latter, statistically converged spectra are computed using conventional Fourier analyses techniques, whereas the former are investigated by way of time-frequency analysis. The findings suggest that at low nozzle pressure ratios -- where the flow resides in a Free Shock Separation state -- strong spectral similarities occur between fixed and transient conditions. Conversely, at higher nozzle pressure ratios -- where the flow resides in Restricted Shock Separation -- stark differences are observed between the fixed and transient conditions and depends greatly on the ramping rate of the transient period. And so, it appears that an understanding of the dynamics during transient start-up conditions cannot be furnished by a way of fixed flow analysis.
Subjects Aerodynamics (excl. Hypersonic Aerodynamics)
DOI - identifier 10.1088/1742-6596/318/9/092001
Copyright notice Copyright © (2011) by the Institute of Physics All rights reserved.
ISBN 9781622765430
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