A Comparison of the Streamline Throughflow and Streamline Curvature Methods for Axial Turbomachinery

The axial flow turbo machinery throughflow equation states that radial gradients of rothalpy, entropy and moment of momentum affect the conservation of tangential vorticity. The streamline throughflow method (STFM) transforms this equation, expressed in terms of stream function in a radial-axial co-ordinate system, to an equation for streamline radial position in a stream function-axial co-ordinate system. The paper assesses the accuracy and efficiency of the STFM relative to the streamline curvature method (SCM) by comparing streamline positions and velocity profiles to analytical results. Test cases include flow through a single actuator disc, flow through twin actuator discs using a coarse computational grid, compressible flows through an almost choked nozzle, through single and twin actuator discs, and swirling flow using sloped stations. Results from the STFM and SCM agreed about equally well with analytical solutions for the same number of streamlines. The STFM, however, was much more tolerant of distorted computational grids and used an order of magnitude less computer time to converge. The test cases show that the STFM is suitable for annuli with large variations in hub and tip radius, for highly swirling and compressible flow, and is more robust and converges faster than the SCM. To demonstrate the practical applicability of the STFM a multistage compressor was simulated and STFM results compared with experiment.