Comparative Study of Turbulence Models in Separated-Attached Diffuser Flow

摘要

Diffuser flow is characterized by locally attached separation bubble which is also common in compressor cascade flow. To predict the separation region accurately with RANS solvers, turbulence enclosure models are critical to the CFD ability to capture adequately the separation. In general two-equation models are regarded as practical choice and developed for diffusion flow, such as k-ε, k-ω, shear stress transportation (SST), as well as v2-f.In this paper, five common turbulence models were selected to predict the attached separation flow in an experiment-studied planar diffuser with the software FLUENT. k-ε model failed to predict the attached separation. S-A model, Wilcox's k-ω model, SST k-ω model and v2 f model predicted the separation bubble near the inclined wall and the S-A model's reattached length is longest while the v2-f model is smallest. The k-ω model presented the same capability with SSt model in capturing the separation bubble along the inclined wall of the diffuser but smaller gradient of velocity near wall in the outlet part.