A STUDY OF NONLINEAR EDDY-VISCOSITY MODELS IN A FLOW SOLVER FOR TURBOMACHINERY

摘要

In the field of computational fluid dynamics for turbomachinery flow applications, two-equation eddy-viscosity models are widely used, as they integrate extensive physical aspects and require an acceptable amount of computer resources. In the area of turbomachinery they are used for flows in various blade configurations, whereas for each case slight advantages or disadvantages may be observed. Although computation results generally show good agreement with real flow quantities, serious deviations appear for complex geometries. Within the frame of the national cooperative project "Turbulente Stroemungen mit starker Stromlinienkruemmung" (turbulent flows with strong streamline curvature) new approaches to turbulence modelling and model extensions were implemented in the Navier-Stokes Solver PANTA (RANS, URANS), which was developed at the Institute of Jet Propulsion and Turbomachinery at the RWTH Aachen University and tested on turbomachinery relevant cases. The objective was to derive improved turbulence models which lead to better flow simulations and predictions of flow quantities in the area of turbomachinery. Thereby, special consideration was given to the effects of streamline curvature. Various turbulence models and model extensions were investigated, which take into account the influence of rotation and streamline curvature. Here, a model extension for the parameterization of the eddy-viscosity coefficient - the method by Rung - and the Explicit Algebraic Reynolds Stress Model by Wallin and Johansson (EARSM) as well as an extension of the model proposed by Hellsten (EARSM-CC) are applied. The improvement potential and the deficits remaining further on of the examined models and model extensions are presented and evaluated.