COMPARISON OF EXPERIMENTS, FULL-ANNULUS CALCULATIONS AND HARMONIC-BALANCE-CALCULATIONS OF A MULTI-STAGE COMPRESSOR

Abstract

The 4.5 stage DLR research compressor Rig250, which is representative of the front stages of a modern high pressure compressor, has been investigated experimentally and numerically. In order, to enable comparisons with the timeresolved experimental data both steady and unsteady numerical simulations have been performed. In these simulations, both time- and frequency-domain methods have been employed. For the time-domain calculations the model consisted of the full annulus mesh of the first two stages including the IGVs and struts located upstream in a swan neck. In total, the mesh has about 1x109 nodes and is distributed over 6000 blocks. For the frequency-domain calculations the Harmonic Balance (HB) method has been used. By exploiting the spatial and temporal periodicity of the configuration the HB method only requires a single passage to be resolved per blade row, thus significantly reducing the mesh size and calculation time. In this work the results of the time- and frequencydomain simulations are compared with each other and the available steady and unsteady experimental data. In particular, the importance of selecting the appropriate Fourier modes and the challenge this presents in multistage configurations is emphasized. The drawbacks and advantages of the two numerical methods are discussed.