Axial and Centrifugal Compressor Mean Line Flow Analysis Method

This paper describes a method to estimate key aerodynamic parameters of single and multi -stage axial and centrifugal com pressors. Th is mean -line compressor code COMDES provides the capability of sizing single and multi -stage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler eq uation , the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code , and are modeled at off design. When run in the off -design analysis mode , it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle . The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor , loading levels and incidence, when matching multi -stage comp ressor blade rows at design and at part -speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three -stage NASA 74 -A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76 -B three -stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off -design speeds by adjusting the variable inlet guide v ane and variable stator geometry angles to control the rotor diffusion factor and incidence angles .