A Study of Instability Phenomenon in a Supercritical Diffuser Flow

Research Project

Project/Area Number	60550127
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Fluid engineering
Research Institution	Kyushu University
Principal Investigator	MATSUO Kazuyasu Graduate School of Engineering Sciences, Kyushu University, 国立大学(その他), 教授 (30037759)
Co-Investigator(Kenkyū-buntansha)	MOCHIZUKI Hiroaki Graduate School of Engineering Sciences, Kyushu University, 総合理工学研究所, 助手 (70038058)
Project Period (FY)	1985 – 1986
Project Status	Completed (Fiscal Year 1986)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
Keywords	Supercritical diffuser / transonic flow / shock wave / choking / 流体振動
Research Abstract	1. The behavior of a shock wave in a supercritical diffuser under a constant overall pressure ratio is classified into a stable oscillation about its mean shock position and an unstable one where a shock wave is generated downstream of its throat and moves upstream and the cycle is repeated. 2. An analysis of the stability criterion of a shock wave which interacts with periodic, lowfrequency downstream pressure disturbances has been performed taking the diffuser efficiency of the subsonic flow downstream of a shock wave into consideration. 3. The behavior of stable and unstable shock waves in a two-dimensional circular diffuser has been experimentally clarified by a schlieren optical method and by pressure measurements. 4. The response and subsequent motion of shock waves by the interaction of small-amplitude pressure disturbances are presended as a function of the Mach number where the shock is initially located and the diffuser efficiency of the subsonic region downstream of the shock. 5. The curve of neutral stability which relates the diffuser efficiency to the Mach number of a shock wave is obtained and it is shown that the criterion agrees well with the present experimental results as well as with the previous experimental ones.