Some Aspects of Acoustic Shock Emission of High-Speed Nozzles

Abstract

The problem of acoustic shock emission of high-speed nozzles is discussed in terms of the theoretical aspects of nonisentropic wave generation. [J. Acoust. Soc. Amer. 45, 339(A) (1968)]. Some of the recent developments in the analytical and computational aspects of the problem are presented with emphasis upon exhaust shocks of conical structure. Initial efforts to isolate the mechanism of shock emission in terms of nonisentropic sources indicate that local velocity fluctuation are of second-order magnitude and serve as a triggering device rather than as actual acoustic flow sources. In effect, the mathematical model indicates that shock-wave emission predominates in the mechanism of high-speed exhaust noise. [This study is supported by the Unsteady Aerodynamics Branch of the National Aeronautics and Space Administration in Huntsville, Alabama.]