NUMERICAL SIMULATION AND THEORETICAL ANALYSIS OF THE 3D VISCOUS FLOW IN CENTRIFUGAL IMPELLERS

Abstract

This paper investigates the three-dimensional viscous flow in centrifugal impellers through theoretical analysis and numerical simulations, which is a summary of the authors’ recent work. A quantitative evaluation of the different contributions to the streamwise vorticity is performed, namely, the passage vortices along the endwalls due to the flow turning; a passage vortex generated by the Coriolis forces proportional to the local loading and mainly active in the radial parts of the impeller; blade surface vortices due to the meridional curvature. In the numerical simulation the NASA Large Scale Centrifugal Compressor (LSCC) impeller with vaneless diffuser is computed at three flow rates. An advanced Navier-Stokes solver, EURANUS/TURBO is applied with an algebraic turbulence model of Badwin-Lomax and a linear k-ε model for closure, for different meshes. An in-depth validation has been performed based on the measured data. An excellent agreement is obtained for most of the data over a wide region of the flow passage. Structures of the 3D flow in the blade passage and the tip region, and their variations with flow rate as well, are analysed based on the numerical results.