Influence of a Hub-Groove on the Unsteady Losses of a Transonic Compressor Stage

Abstract

In this paper the influence of a non-symmetrical sidewall-contour on the flow field of an axial compressor is investigated. In earlier studies, carried out at the DLR Institute of Propulsion Technology in Cologne, it has been shown that it is possible to influence secondary flow regimes by a non-symmetrical sidewall contour. With the help of the contour a vortex is generated that serves as an aerodynamic barrier and thus reduces the flow transport orthogonal to the main flow direction. In this paper the described method of flow manipulation is investigated for the compressor rotor at the hub wall. It turns out that despite the unsteady inflow conditions the vortex is stably generated and works as an aerodynamic separator. The rotor hub region increases its flow capacity. A higher pressure ratio is achieved at a highly loaded operating point. The efficiency at this point remains unchanged. List of Symbols and Abbreviations m M-relative mass flow, y +-dimensionless wall distance, η-isentropic efficiency, π-total pressure ratio, ω-vorticity , BPrVar-back pressure variation, MVDRmeridional velocity density rate, OP-operating point, PR-pressure ratio, TVD-Total Variation Diminishing