Spectra of noise and amplified turbulence emanating from shock-turbulence interaction

This work is a small extension of our NACA studies of the early fifties that predicted amplification of turbulence on passing through a shock wave (observed for turbul ent boundary 1 ayers), as well as the generat i on of intense noise (observed for supersonic jets). The first solved the basic gasdynamics problem of the interaction of an infinite planar shock with a single three-dimensional spectrum component of turbulence (an oblique sinusoidal "shear wave"). The second developed the comprehensive 30 spectrum analysis necessary to generalize the scenario to the interaction of a shock wave with convected homogeneous turbulence. Numerical calculations were carried out to yield curves (vs. Mach number) of rms sound pressure, temperature fluctuation, and two components of turbulent velocity downstream of the shock, for two cases of preshock turbul ence. The present numeri cal study reproduces these for one case and provides in addition their one-dimensional power spectra (vs. wavenumber or frequency). Ratios of the