Modelling the Streamline Curvature Effects in Turbomachinery Flows

Turbomachinery flows show significant streamline curvature with corresponding effects on turbulence development. Generally, linear eddy viscosity turbulence models, which are widely used in industrial aerodynamic design, do not predict these effects accurately, leading to less reliable RANS-simulations. In this work, therefore, a modification is made to the two-equation turbulence model of Wilcox [1]. Although this extension is a simple and pragmatic approach, the effects of streamline curvature are accurately reproduced for many presented applications, ranging from simple generic test cases to multistage compressor flows. Improved predictions of performance maps are achieved, which is mainly due to improved modelling in regions with higher streamline curvature, e.g. tip vortex and end-wall boundary layers. The curvature correction enables a greater mass flow range to be simulated and increases the numerical stability. Furthermore, the new approach requires only local variables, which makes it applicable to complex flows and easy to implement in existing codes.