A time-efficient optimization of subsonic centrifugal compressors with vaneless diffuser using 1D mean line approach based on empirical loss correlations

Abstract

The present paper focuses on the time-efficient optimization of subsonic centrifugal compressors with vaneless diffuser using a one-dimensional mean line approach based on empirical loss correlations. The main motivation for this research is the application of a compressor loss model, in-house developed and tested, in optimization task for the preliminary design of centrifugal compressor used in turboprop applications. While operational, various loss mechanisms and physical phenomena may occur in centrifugal compressors. Models of these losses, which are precisely described in this work, combined with off-design performance prediction algorithm, constitute an essential tool for predicting the off-design behavior of centrifugal compressors. This study utilizes an off-design performance prediction algorithm based on an iterative loop as the core of the geometry optimization process. The reconstruction of the subsonic Eckardt-O compressor’s geometry is described in great detail, and it is then transformed into parametric model using Bezier curves for further optimization. This process included the optimization of a total of 36 parameters describing various geometrical elements. A suitable candidate was found as a result of this optimization. By comparing the flow paths, it was concluded that the optimized compressor is more economical in terms of connection dimensions, which can be important in certain applications. Another comparison showed that the optimized compressor achieves comparable results in terms of pressure ratio as the original geometry and surpasses it in terms of efficiency by 1.49%.