Vortex Shedding and Wave Propagation in Transonic Two-dimensional Cavity Flows

Article type: Research Article

Authors: Khan, M.U. | Hirahara, H. | Kawahashi, M.

Affiliations: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Urawa, Saitama 338-8570, Japan. | Faculty of Engineering, Saitama University, 255 Shimo-Okubo, Urawa, Saitama 338-8570, Japan.

Abstract: Flows over a two-dimensional rectangular cavity, which length to depth ratios are 1 and 2, were studied experimentally and numerically at Mach numbers, 0.55 to 0.85. The flow pattern and unsteady wave propagation were visualized by using a schlieren technique. The pressure fluctuation in the cavity was analyzed by FFT. Its spectrum distribution was discussed for several flow Mach numbers. The experimental results were compared with the previous theory in terms of the discrete frequencies. Comparing experimental results and those theoretical predictions, oscillation modes in transverse and longitudinal directions were discussed with visualized flow images. A numerical simulation was carried out by a finite difference method at a free stream Mach number of 0.8. The numerical simulation demonstrated the periodic formation of the vortices at the leading edge and shedding to the trailing edge. A comparison of the numerical result with experimental observation shows a good agreement in terms of flow pattern in the cavity.

Keywords: subsonic and transonic cavity flow, sound emission, schlieren technique

Journal: Journal of Visualization, vol. 3, no. 4, pp. 331-339, 2001