The design and optimization of a multistage radial compressor vaneless diffuser, cross-over and return channel is presented. An analytical design procedure for 3D blades with prescribed load distribution is first described and illustrated by the design of a 3D return channel vane with leading edge upstream of the cross-over. The analysis by means of a 3D Navier–Stokes solver shows a substantial improvement of the return channel performance in comparison with a classical 2D channel. Most of the flow separation inside and downstream of the cross-over could be avoided in this new design. The geometry is further improved by means of a 3D inverse design method to smooth the Mach number distribution along the vanes at hub and shroud. The Navier–Stokes analysis shows a rather modest impact on performance but the calculated velocity distribution indicates a more uniform flow and hence a larger operating range can be expected. The impact of vane lean on secondary flows is investigated and further performance improvements have been obtained with negative lean.

Issue Section:
Technical Papers
Keywords:
compressors, channel flow, Navier-Stokes equations, flow separation, Mach number, swirling flow
Topics:
Blades, Compressors, Design, Flow (Dynamics), Geometry, Mach number, Pressure, Flow separation, Optimization, Suction
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Copyright © 2004
 by ASME
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