عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In present investigation, the flow field passing through a highly loaded low pressure (LP) turbine cascade is numerically studied at design and off-design conditions. The Field Operation and Manipulation (OpenFOAM) platform is used as the Computational Fluid Dynamics (CFD) tool. Firstly, the influences of grid resolution on the results of RANS k-ε and k-ω models and LES utilizing Spalart-Allmaras subgrid scale model (LES-SA) are investigated and compared with those of the experimental measurements. Numerical results show that a pressure under-shoot is obtained near the end of blade pressure surface which is highly sensitive to grid resolution and flow turbulence modeling. Secondly, it is shown that the LES-SA model is able to resolve separation on the coarse and fine grid resolutions. The LES-SA results show the separation about S/C=0.85 whereas the experiments measure it about S/C=0.75.Thirdly, the off-design flow condition is modeled by imposing negative and positive inflow incidence angles. The numerical results of LES-SA model show that a separation bubble is generated on blade pressure side. The calculation of total pressure drop at incidence angles between -20 and +8 degrees illustrates that the k-ω and LES-SA models could estimate the minimum total pressure drop at the design point.
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