Abstract
Modeling the heat transfer characteristics of highly turbulent flow in gas turbine film cooling is important for providing better insights and engineering solutions to the film cooling problem. This study proposes a modified detached eddy simulation (DES) model for better film cooling simulations. First, spatially varying anisotropic eddy viscosity is found from the results of the large eddy simulation (LES) of film cooling. Then the correlation for eddy viscosity anisotropy ratio has been established based on the LES results and is proposed as the modification approach for the DES model. The modified DES model has been tested for the near-field film cooling simulations under different blowing ratios. Detailed comparisons of the centerline and 2D film cooling effectiveness indicate that the modified DES model enhances the spanwise spreading of the temperature field. The DES model leads to deviations of 62.4%, 39.8%, and 33.5% from the experimental centerline effectiveness under blowing ratios of 0.5, 1.0, and 1.5, respectively, while the modified DES reduces the deviations to 51.5%, 26.7%, and 28.9%. The modified DES model provides a promising approach for film cooling numerical simulations. It embraces the advantage of LES in resolving detailed vortical structure dynamics with a moderate computational cost. It also significantly improves the original DES model on the spanwise counter rotating vortex pair (CRVP) spreading, mixing, and effectiveness prediction.
Highlights
Gas turbines provide power to various applications such as power generation, aero-engines, land and sea-based transportation, and mechanical drives [1]
Simulation results were obtained with the Unsteady Reynolds-averaged Navier–Stokes equations (URANS), detached eddy simulation (DES), and modified DES model
URANS results were mainly used to provide a reference for the centerline effectiveness comparison, whereas the instantaneous and time-averaged contours obtained with DES and modified DES were analyzed in detail
Summary
Gas turbines provide power to various applications such as power generation, aero-engines, land and sea-based transportation, and mechanical drives [1]. A flat plate and leading-edge film cooling simulation by Sakai et al [27] clearly showed that RANS underpredicts the spanwise spreading of film cooling jets compared to the measured data and DES results This shows the importance of the DES model in practical applications and makes it very useful to gas turbine designers. The well-developed enhanced spanwise eddy viscosity approach, which was originally proposed to create better RANS film cooling simulations, was successfully adopted as a modification to the DES model in Yu and Yavuzkurt [25]. The time-averaged measurements resulted in a base dataset on film cooling effectiveness that can be used to study and validate the modified DES under different blowing ratios. The results are analyzed and compared with the experimental data to demonstrate the benefits of the three-directional eddy viscosity modified DES model
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