Large-eddy simulation of turbulent separated flows over an isolated air

Abstract

The large eddy simulation is used to solve the separated flows over an NACA0012 isolated airfoil with the freestream Reynolds number of 2.8 x 10 at angles of attack from 0° to 45° . Separated flow structures over the isolated airfoil and corresponding aerodynamic characteristics including pressure fluctuations at different angles of attack are presented in details. In the numerical simulation, a weakly compressible flow model and the body fitted grid technique are used. Introduction The study of the flow past an isolated airfoil is closely related to its application to the aircraft wings, propellers, and helicopter rotor blades. Particularly, in the development of high lift wings for short take off and landing aircraft, the lifting devices oftentimes offer their optimum performance at the condition of separation. Thus it is very necessary to investigate structures and characteristics of separated flows at large angles of attack by use of one effective numerical method. Because the Large eddy simulation is an accurate method of simulating complex turbulent flows in which the large scale turbulent structures are directly computed while small scales are modeled, this paper uses this method to solve Navier Stokes equations which control large scale turbulent structures and to present characteristics of pressure fluctuations on the surface of the airfoil. Copyright © 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. A Weakly-Compressible Flow Model and the Large Eddy Simulation Governing Equations In this numerical simulation, we used a weakly compressible flow model presented by Strigberger and Song et al to compute the separated flows over an isolated airfoil. The governing equations are