22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-3.5.3

EXPERIMENTAL STUDY ON SELF INDUCED EXCITATION PHENOMENA OF OPPOSING JET IN SUPERSONIC FLOW

K. Karashima (1), S.Aso, G. Takami (2), K.Sato (3)
(1) Nishinippon Institute of Technology, Japan; (2) Kyushu University, Japan; (3) ISAS, Japan

Keywords: supersonic flows, opposing jets, shock waves

The self-induced oscillations in supersonic opposing jet to supersonic free stream have been investigated. In opposing jet flows in supersonic flows the flow fields have stable region and unstable region, depending on the ratio of total pressure of free stream to total pressure of opposing jet. In the present study the ratio of total pressure of free stream to total pressure of opposing jet , P0j/P0, are selected as 0.469, 0.655, 0.984 and 1.51 . Free stream Mach number and opposing jet Mach number are 2.5 and 1.5 respectively. The experimental model consists of semi-spherical nose and cylindrical body. The flow fields are visualized by the Schlieren technique and recorded by high speed video camera. Also pressure fluctuations on the model surface are measured. The results show that there are two features in self-induced shock wave oscillations and bow shock wave oscillation is observed in lower total pressure ratio and recompression shock wave oscillation is observed in higher total pressure ratio. Also the peak frequencies for both cases are different. The pressure time history and instantaneous flow pattern show good correlations. The global properties of selfindeuced shock wave oscillation of opposing jets in supersonic flows have been revealed.

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