An Integrated Throughflow Method for the Performance Analysis of Variable Cycle Compression Systems

A streamline curvature method based integrated throughflow analysis approach is newly developed to deal with component matching problems of variable cycle compression systems. The construction of variable cycle compression system is modularly modelled in the procedure. Splitting and confluent flow are elaborately disposed. A numerical method based on the "streamline floating"character of streamline curvature method is developed to model the function of forward variable area bypass injector. Moreover, extensive models used in the throughflow calculations, including minimum loss incidence, deviation and loss models were assessed, selected and modified. Finally, code validations were conducted on three representative traditional compressors, i. e. NASA rotor 67, NASA stage 37 and a custom-designed low-speed repeating four-stage compressor. Both the predicted overall characteristics and spanwise profiles agree reasonably well with the experimental data. The validated procedure was finally used to sketch the performance maps of a double bypass compression system under two different control rules, i. e. the first bypass throttling and the second bypass throttling. The results show some aspects of the difficulties and complications in operating a variable cycle compression system, and meanwhile, demonstrate the superiority of the newly developed integrated throughflow method.