Research on the numerical simulation of aerodynamic noises of shear flow based on linearized Euler equations

Abstract

This paper numerically simulated the propagation of different sound sources in inhomogeneous media through solving linearized Euler equations (LEE). In space, dispersion-relation-preserving (DRP) scheme and compact difference scheme of high-order accuracy were used for dispersion. In time, Runge-Kutta (Low Dispersion and Dissipation Runge-Kutta) method with low-dispersion and low-dissipation was applied to push ahead. Nonreflecting boundary condition was adopted at the far-field boundary. In the meanwhile, numerical filtering was conducted for numerically computational results. The scattering of Gaussian pulse source around a cylinder was taken as a verification example. Numerical simulation results were compared with theoretical solutions to verify the correctness of numerical simulation method of aerodynamic noises in this paper. Numerical simulation was conducted for the sound propagation of monopole sound source in the shear layer and the sound propagation of different modes of sound sources in and out the tailpipe nozzle of engines. Numerical simulation results showed: The treatment for dispersion schemes and boundary conditions in this paper could well simulate the propagation process of aerodynamic noises in the shear layer; the shear flow would have an impact on the amplitude and propagation direction of aerodynamic noises in the flow field; for different modes of pipe sound sources, the shear layer would cause different refraction effects; the direction of sound radiation was rather centralized for the single pipe mode and dispersive for the multi-pipe mode. In addition, the dispersive-ness of sound radiation became stronger and stronger with the increased pipe modes. Namely, the directivity of sound presented to be a petal. The shear layer would reduce the dispersion effect of multi-pipe modes in the direction of sound radiation.