A CFD-Based Throughflow Solver Using Cascade Potential Theory for Axial Compressor Flow Modeling

Abstract

This paper describes the use of the Hess & Smith cascade potential method as an additional feature for throughflow modeling. This method is incorporated inside ASTEC, a CFD-based throughflow solver developed by Safran Tech providing local blade loading information for blade force and loss modeling. The test cases are all subsonic, composed of two compressors cascades and a low speed compressor. The two profile families for the cascades are a classical NACA 65 009 and a controlled diffusion cascade designed by the Whittle Laboratory. The compressor is the well studied CME2, a research single stage designed by Safran Aircraft Engines. From the potential calculation, boundary layers and wakes are calculated on the blades providing deviation angles and profile losses. The tip leakage losses are also estimated from blade loading at the tip of a rotor. The results are compared to MISES code predictions, RANS simulations, experimental data and classic Lieblein empirical correlations. This work aims to model compressors flow with geometry-based classic analytical methodologies for a minimal use of empiricism. The predictions are good on bi-dimensional cascades cases compared to several other methodologies and at mid-span for the multiple incidences considered compared to experimental cascade results. For the compressor case, the blade loading near mid-span of the rotor blades show good agreement compared to RANS results leading to an overall good capture of the performance characteristic trends near design point. There is still room for improvements near the end-walls, mostly due to the lack of hub boundary layer model in the actual methodology. These results still build a step on which the enrichment of the flow model can be pursued.