Assessment of a novel k–ω 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–ω 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–ω model, RNG k–ε 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–ω model had an advantage over other models 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 other models, closer to the experimental result. The detailed parameter examination indicated that the nonequilibrium parameter a₀ 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 a₀ is recommended for bettering the simulation accuracy.