Reynolds Number Effects on Internal Flow and Performance in a Transonic Centrifugal Compressor Impeller

Abstract

This paper presents effects of Reynolds number on the flow field and performance in a transonic centrifugal compressor impeller. Steady-state single passage RANS simulations with the low-Reynolds number k-omega turbulence model have been conducted to investigate the effects. The machine Reynolds number was changed in the range of 10⁴ to 10⁶ under the similarity rule in turbomahines. The substantial changes in vortical flow structures and separated flow patterns are described by taking advantage of the data mining techniques: vortex identification and limiting streamline topology analysis with the line integral convolution (LIC) method. The simulations also show the performance deterioration with Reynolds number decrease, but its trend is somewhat different from the expectation from the previous research papers.