Preliminary design optimization of profile losses in multi-stage axial compressors based on complex method

Abstract

This paper illustrates a numerical technique undertaken for preliminary design optimization of profile losses in multi-stage axial compressors. Design process has been carried out based on one-dimensional row by row calculations along compressor mean line. The main objective of the optimization process was to find the best distribution of pressure ratios along compressor stages in order to maximize the overall efficiency, which is itself a non-linear function of governing variables. In this respect, only profile losses, identified as the most dominant ones, are focused on and minimized during the optimization process. Pressure ratios of stages have been taken as design variables. Diffusion factor and De Haller number of each blade row were considered as the main constraints during the optimization process. Numerical optimization was based on a sequential search technique, referred to as complex method. Design process in parallel to the numerical optimization is examined on a ten-stage axial compressor of known general performance data. Final results showed an increase of about 2.7 per cent in the total efficiency relative to its initial value calculated during the preliminary design process.