Application of a CFD Code for Unsteady Transonic Aerodynamics to Problems in Aeroacoustics

Abstract

Prediction of unsteady aerodynamic pressure distributions is an important step towards analyzing the flutter characteristics of an airplane. For this purpose, a Computational Fluid Dynamics code, originally developed for predicting steady transonic flow past bodies of complex geometry, was extended to handle unsteady aerodynamic problems, in which the unsteady solution could be viewed as a harmonic perturbation to the steady transonic flow. The predicted unsteady flow effects were compared with linear solutions for subsonic flow problems. The predicted results were also compared with available experimental data on unsteady pressure distributions on an oscillating wing in transonic flow. In all these cases, excellent agreements were obtained.Scattering and diffraction play important roles in determining noise generated by turbulent sources near solid bodies. Scattering of engine noise by the fuselage, wings and the empennage influences community and interior noise levels in an aircraft. There are many areas in aeroacoustics where application of advanced Computational Fluid Dynamics (CFD) tools can provide valuable insight into the physics of the problem. In this paper, applications of the above unsteady CFD code to several specific areas are illustrated.