Development of a 2-D Compressor Streamline Curvature Code

Abstract

Two-dimensional compressor flow simulation software has always been a very valuable tool in compressor preliminary design studies, as well as in compressor performance assessment, operating under uniform and non-uniform inlet conditions. In this context, a new streamline curvature (SLC) software has been developed capable of analyzing the flow inside a compressor in two dimensions. The software was developed to provide great flexibility, in the sense that it can be used as: a) A performance prediction tool for compressors of a known design, b) A development tool to assess the changes in performance of a known compressor after implementing small geometry changes, c) A design tool to verify and refine the outcome of a preliminary compressor design analysis, d) A teaching tool to provide the student with an insight of the two-dimensional flow field inside a compressor and how this could be effectively predicted using the SLC method, combined with various algorithms and loss models, e) A 2-D compressor model that can be integrated into a conventional 0-D gas turbine engine cycle simulation code for the investigation of the influence of non-uniform radial pressure profiles on whole engine performance. Apart from describing in detail the design, structure and execution of the SLC software, this paper also stresses the importance of developing robust, well thought-out software and highlights the main areas a potential programmer should focus on in order to achieve this. This manuscript highlights briefly the programming features incorporated into the development of software before continuing to explain the internal workings of individual algorithms. The paper reviews in detail the set of equations used for the prediction of the meridional flow field. Numerical aspects of the application procedure of the full radial equilibrium equation are examined. The loss models incorporated for subsonic and supersonic flow are presented for design and off design operating conditions. Deviation angle rules are presented, together with the parameters for quantifying the diffusion process. Moreover, the methods used for the prediction of surge and choke are discussed in detail. Finally, the end wall boundary layer displacement thickness calculation is discussed briefly, in conjunction with the blockage factor computation. The code has been validated against experimental results which are presented in this paper together with the strong and weak points of this first version of the software and the potential for future development.