Variation of Acoustic Energy Across Sudden Area Expansions Sustaining a Subsonic Flow

The acoustic energy balance of a sudden area expansion is known to be altered in the presence mean flow. In this work, Ronneberger’s quasi-steady model describing response sustaining subsonic flow arbitrary Mach number revisited using absorption coefficient, shown function inlet [Formula: see text], cross-sectional ratio and upstream reflection coefficient text]. These analytical predictions are tested two-step numerical strategy, whereby variables obtained Reynolds-averaged Navier–Stokes simulations fluctuating computed in-house linearized equations solvers. agreement between results found excellent for all geometries, flows, boundary conditions investigated. generation by observed analytically numerically high-Mach-number flows undergoing slight increase given conditions. Conversely, it that substantial damping occurs across expansions characterized wide range parameters Moreover, entropy vorticity fluctuations generated at expansion, but have negligible impact on low intermediate numbers. Finally, reasonably accurate up Helmholtz numbers corresponding frequency many industrial applications.