Behaviour of turbulence models in steady and unsteady transonic cascade flows

摘要

The behaviour and effects of turbulence models in unsteady 2-D transonic cascade flows are studied. This qualitative numerical experimentation is to understand the flow mechanism and the effects of turbulence models in such a complex flow field. Large difference between the turbulence models used are observed in the parameters which are sensitive to the shock location such as pitching moment. The Johnson-King model (JKM) is known to predict shock locations slightly upstream of the Baldwin-Lomax model (BLM) in some adverse pressure gradient conditions in steady flows. It is confirmed that this tendency is unchanged in the unsteady flows tested. The unsteady cases have a time delay when compared with the steady cases. This time delay is slightly smaller with the JKM than the BLM. This is thought to be caused by the addition of the streamwise convection and diffusion effects in the JKM. The maximum Reynolds shear stresses around the trailing edge vary significantly between the turbulence models. However the wake region seems to be interacting with the separated region and careful study into handling of the wake seems to be necessary.