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International Journal of Aerospace Engineering
Volume 2015, Article ID 751029, 7 pages
Research Article

Frequencies of Transverse and Longitudinal Oscillations in Supersonic Cavity Flows

1Department of Energy and Environmental Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka 816-8580, Japan
2Power Systems Plant Engineering Department, Mitsubishi Heavy Industries, 2-1-1 Shinhama Arai-Cho, Takasago, Hyogo 676-8686, Japan
3Plant and Machinery Division, Nippon Steel & Sumikin Engineering, 46-59 Nakabaru, Tobata-Ku, Kitakyushu, Fukuoka 804-8505, Japan

Received 29 July 2015; Accepted 4 October 2015

Academic Editor: Keh-Chin Chang

Copyright © 2015 Taro Handa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A supersonic flow over a rectangular cavity is known to oscillate at certain predominant frequencies. The present study focuses on the effect of the cavity length-to-depth () ratio on the frequency for a free-stream Mach number of 1.7. The pressure oscillations are measured by changing the ratio from 0.5 to 3.0, and the power spectral density is calculated from the temporal pressure signals for each ratio. The results demonstrate that the spectral peaks for an ratio of less than ~1 and greater than ~2 are accounted for by the feedback mechanisms of the transverse and longitudinal oscillations, respectively. The results also demonstrate that the spectral peaks in the transition (1 <~ <~ 2) are accounted for by either of the two feedback mechanisms of transverse and longitudinal oscillations; that is, the flows under the transition regime oscillate both transversely and longitudinally.