Revision as of 10:58, 19 October 2011

Flows Around Bodies

Underlying Flow Regime 2-11

Abstract

The flow around airfoils at high (beyond stall) angles of attack is a fundamental problem of external aerodynamics. Conventional RANS turbulence models are not only incapable of predicting a steady mean flow for this UFR with acceptable accuracy but also "by definition" cannot capture its essential features (inherent 3-dimensionalty and unsteadiness) which are of significant interest for aero-acoustics and aero-elasticity applications. These circumstances have defined the primary choice of specific test case, namely the flow around a NACA0021 airfoil at 60° angle of attack, as the only one for which experimental data on unsteady as well as mean flow characteristics are available [‌27, 28] and for which a wide spectrum of computations with different CFD codes has been carried out in the framework of the EU DESider Project [‌5]. The very similar case of the thinner NACA0012 airfoil in deep stall is employed as a related secondary test case from which past experience allows additional best practice advice (BPA) to be extracted. Two principal purposes are envisaged for this UFR case and BPA. Firstly, to document the experience gained with respect to the most suitable computational techniques, in order to advise users considering the practical computation of similar flows. Secondly, the case is envisaged as an ideal verification case for testing new developments or implementations of turbulence-resolving models, such as hybrid RANS-LES approaches.

Contributed by: Charles Mockett; Michael Strelets — CFD Software GmbH and Technische Universitaet Berlin; New Technologies and Services LLC (NTS) and St.-Petersburg State Polytechnic University