Performance prediction and parametric study of the combined axial-centrifugal compressor

Axial and centrifugal compressors are essential components in gas turbine engines, effectively serving various applications such as aircraft propulsion, marine and land transportation, and power generation. A combined axial-centrifugal compressor stands out as an effective solution, harnessing the advantages of both compressor types. This research delivers a thorough examination of the energy loss correlations associated with these compressors. A carefully selected configuration for the combined compressor is established, leading to the development of a one-dimensional (1D) mean line model. This robust model is employed to accurately predict the performance of the axial, centrifugal, and combined axial-centrifugal compressors. The predictions generated by this model align remarkably well with experimental data from a gas turbine engine operating line. The average discrepancies in pressure ratio and isentropic efficiency predictions for the axial compressor are impressively low at 0.6% and 4.5%, respectively. For the centrifugal compressor, the average differences are also minimal, sitting at 3.4% for pressure ratio and 3.5% for efficiency. Furthermore, the average discrepancy in pressure ratio prediction for the combined compressor reaches just 3.4%. Additionally, the performance curves for the axial, centrifugal, and combined compressors are calculated utilizing the developed model. Finally, an in-depth parametric study is conducted to systematically investigate how various factors such as the solidities of the axial rotor and stator, the axial length of the impeller, and the tip clearance values of the axial rotor and impeller impact the performance of the combined compressor.