Aspects of Numerical Simulation of Turbomachinery Flows

In light of the Vision 2020 goals formulated by ACARE (Advisory Council for Aeronautics Research in Europe), the development of new aircraft engines has become a very challenging task. Rather ambitious aims have been set with respect to environmental concerns, operational efficiency as well as manufacturing costs and time-to-market. This necessitates fast and reliable design tools being able to analyse even intricate details of a future engine. The use of simulation methods in the industrial design process has thus increased significantly over the past decade and is continuing to do so. This is especially true for the gas turbine aerodynamics representing the primary problem in turbomachinery. Turbomachinery flows are characterized by the succession of rotating and non-rotating blade rows in the compressor and turbine components. Thus, the accurate prediction of the flow in these blade rows as well as their interaction is of uppermost importance in numerical flow simulation (CFD) in turbomachinery today. To this end, DLR has devised the flow solver TRACE, which solves the compressible Navier-Stokes equations in a Finite-Volume framework. The multistage capability along with a hybrid (structured/unstructured) approach allows for the computation of complex geometries. The solver also comprises additional modules addressing problems such as aeroacoustics, aeroelasticity, multi-phase and real-gas flows. A linearized and an adjoint solver are available. After a brief introduction into the essential problems of turbomachinery CFD, the presentation addresses the various capabilities of TRACE along with typical application examples. Additionally, two issues will be discussed in some more detail, viz. turbulence modelling and erosion prediction. Finally, an outlook will be given