Computations of Unsteady Separating Flows over an Oscillating Airfoil

摘要

Unsteady separating flows over oscillating airfoils occur in many important engineering applications, such as airplanes, helicopter rotors in forward flight, and turbine blades. There are some distinct features of the unsteady separating flows (dynamic stall) over a rapidly oscillating airfoil that draw the special attention of many scientists. These features include large amounts of force and moment hysteresis and oscillatory pressure fluctuations. In most situations, these features of dynamic stall significantly limit the performance of the device. The primary objective of the present study is to identify the most accurate, robust, and economic turbulence model for dynamic stall computations. However, testing all of the turbulence models available is simply impractical. Alternatively, only a few popular and representative models are selected after surveying papers and reports on separated flows. The Baldwin-Lomax (B-L) model is selected because of its popularity as a zero-equation model. The Spalart-Allmaras (S-A) model is chosen among one-equation models because of its excellent performance. Finally, the k- e model is selected because it is the most popular two-equation model.