Viscous-flow two-dimensional analysis including secondary flow effects

During the last few, decades extremely powerful Quasi-three-dimensional (3D ) codes and fully 3D Navier-Stokes solvers have been developed anti success fully utilized in the design process and optimization of multistage axial-f low compressors. However, most of these methods proved to be difficult in h andling and extremely time consuming. Due to these disadvantages, the prima ry stage design and stage matching its well as the off-design analysis is n owadays still based on just 2D methods incorporating loss-, deviation- and end wall modeling. Only the detailed 3D optimization is normally. performed by means of advanced 3D methods. In this paper a fast and efficient 2D cal culation method is presented, which already in the initial design phase of multistage axial flow compressors, considers the influence of hub leakage f lows, tip clearance effects, and other end wall flow phenomena. The method is generally based on the fundamental approach by Howard and Gallimore (199 2). In order to allow a more accurate prediction of skewed and nondeveloped boundary layers in turbomachines, an improved theoretical approach was imp lemented. Particularly the splitting of the boundary layers into an axial a nd tangential component proved to be necessary in order to account for the change between rotating and stationary end walls. Additionally, a new appro ach is used for the prediction of the viscous end wall zones including hub leakage effects and strongly skewed boundary layers. As a result, empirical correlations for secondary flow effects are no longer required. The result s of the improved method are compared with conventional 2D results includin g 3D loss- and deviation-models, with experimental data of a three-stage re search compressor of the Institute for Jet Propulsion anti Turbomachinery o f the Technical University of Aachen and with 3D Navier-Stokes solutions of the V84.3A compressor and of a multistage Siemens research compressor. The results obtained using the new method show a remarkable improvement in com parison with conventional 2D methods. Due to the high quality and the extre mely short computation time, the new method allows an overall viscous desig n of multistage compressors for heavy duty gas turbines and aeroengine appl ications.