Computation of Laminar-Turbulent Transition in Turbumachinery Using the Correlation Based γ-Re_θ Transition Model

The accurate numerical simulation of the flow through turbomachinery depends on the correct prediction of boundary-layer transition phenomena. Especially heat transfer and skin friction investigations demand a reliable simulation of the transition process. Many models have been developed to simulate the transition process, ranging from simple algebraic models to very sophisticated transport models. But nearly all models suffer from the need to determine boundary layer parameters and from their difficult application in three-dimensional flows. Therefore, in this work the correlation based γ-Re_θ transition model developed by Menter and Langtry is implemented into the in-house Reynolds-averaged Navier-Stokes solver. This model avoids the calculation of non-local parameters and is thus very suitable for three-dimensional general flow situations. Two additional transport equations, one for the intermittency and one for the momentum thickness Reynolds number, which is a criterion for the transition onset, are added to the well known SST turbulence model by Menter. Instead of the proprietary model correlations by Menter et al. the authors used correlations by other research groups within the in-house code and tested these correlations for simple flat-plate test cases. The non-satisfying results indicate a strong code dependency of the model. Therefore also in-house correlations are presented and validated. A comprehensive study of the model performance on the well known ERCOFTAC flat plate test cases is performed. After this validation the model is applied to the steady flow in a T106A and a T106 turbine cascade.