Analysis of High Speed Multistage Compressor Throughflow Using Spanwise Mixing

Abstract

Previous RAE papers have described the application of an S1-S2 flow calculation system, which does not model spanwise mixing, to the RAE C147 high speed research core compressor. Although this has proved a valuable design and analysis tool, it is shown by comparison with detailed interstage traverse measurements that it does not model accurately the radial profiles of stagnation temperature, pressure and flow angle as they develop through the C147. Published work utilising low speed compressor measurements has shown that the inclusion of spanwise mixing terms in throughflow analysis can improve the modelling of radial profiles while allowing more realistic loss models to be used. This paper describes the application of the Gallimore/Cumpsty spanwise mixing model to the C147 compressor. A brief description of the modelling is given, especially the simple annulus wall model not covered by the Gallimore/Cumpsty papers. Then a model of the C147 flow is constructed using simple endwall loss and deviation assumptions, together with other changes needed to represent what seems to be a hub stall. It is concluded that the mixing terms enable realistic radial distributions of loss and deviation to reproduce the observed flow. The temperature mixing terms are particularly important in a high speed unit because they prevent the erroneous accumulation of high temperatures near the walls.