Numerical Simulation of a Radial Difusor Airflow Considering Different Turbulence Models and Computational Parameters

In the present work are presented results from numerical simulations performed with the ANSYS-CFX code. It is studied a radial diffuser flow case, which is the main academic problem used to study the flow behavior on flat plate valves. The radial flow inside the diffuser has important behaviors such as the turbulence decay downstream and recirculation regions inside the valve flow channel due to boundary layer detachment. These flow structures are present in compressor reed valves configurations, influencing in a greater extent the compressor efficiency. The main target of the present paper was finding the simulation set-up (computational domain, boundary conditions and turbulence model) that better fits with experimental data published by Tabatabai and Pollard (1987). The local flow turbulence and velocity profiles were investigated using four different turbulence models, two different boundary conditions set-up, two different computational domains and three different flow conditions (Rein – Reynolds number at the diffuser inlet). Where used the Baseline (BSL) k-ω; the k-ε; the RNG k-ε; and the Shear Stress Transport (SST) k-ω turbulence models. The performed computational results analysis and comparison with experimental data show that the choice of the turbulence model, as well as, the choice of the other computational conditions, play an important rule on results physical quality and accuracy.