Assessment of a novel k-omega turbulence model for transonic centrifugal impeller simulations

Numerical simulation of high pressure ratio transonic centrifugal compressors is challenging for the existing turbulence models. A lagged k-. model proposed by Olsen and Coakley for nonequilibrium effects was first applied to simulate the transonic centrifugal impeller SRV2-O. As comparative case studies, four other turbulence models (k-omega model, RNG k-epsilon model, SST-CC model, and EARSM model) were also computed. The comparison showed that (i) the selection of the turbulence model had a great influence on SRV2-O impeller simulations; (ii) the lagged k-omega model had an advantage over othermodels in terms of overall pressure ratio and internal flow characteristics; and (iii) the lagged model predicted a smaller blockage area caused by leakage vortex breakdown than othermodels, closer to the experimental result. The detailed parameter examination indicated that the nonequilibrium parameter a(0) in the lagged model had little influence on the Mach number distribution and choking mass flow rate but a significant influence on the static pressure on the shroud casing. For a higher Mach number compressor, a smaller a(0) is recommended for bettering the simulation accuracy.