Abstract
Large eddy simulations on film cooling hole array on a flat plate was carried out to investigate upstream turbulence effect. Circular cylinders were configured to create a turbulent boundary layer and its diameter has been adjusted to generate 13% upstream turbulence intensity in the main flow. Due to the small pitch to diameter configuration of the cylinder, two-dimensional LES analysis was carried out in advance and the results showed that LES was an essential method to resolve flow field around and downstream circular cylinder, which was not available in RANS simulations. The three-dimensional LES results showed reasonable agreement in turbulence intensity and normalized velocity distributions along the vertical with measured data. According to the blowing ratio, the cooling flow coverage on the surface along the stream-wise direction was varied and well agreed with measured data. Additionally, upstream boundary flows were partially ingested inside the cooling hole and discharged again near along the centerline of the cooling hole. This accounted for film cooling effectiveness distribution inside the cooling hole surface and along the centerline. The current study revealed that the LES for predicting turbulent boundary layer behaviors due to upstream turbulence generation source was an effective and feasible method. Moreover, the LES effectively resolved flow fields such as film cooling flow behaviors and corresponding film cooling effectiveness distributions.
Highlights
To improve gas turbine engine performances such as specific power and efficiency, the turbine inlet temperature of the gas turbine should be increased
In this study, Large Eddy Simulation (LES) analysis has been used for predicting upstream circular cylinder effect on the film cooling flow on the flat plate, which is discharged far downstream of the circular cylinder row
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Summary
To improve gas turbine engine performances such as specific power and efficiency, the turbine inlet temperature of the gas turbine should be increased. Judging from the results of previous studies mentioned above, as flow fields of the combustor and turbine in gas turbines usually experience very high turbulent flows, methods are required to introduce turbulence information when using the LES method to predict problem-dependent eddies in the simulation and its effects on combustor and turbine performances. Implementing obstacle geometry in the computational domain at the upstream of the flow domain of interest is an effective method to introduce turbulence information in the boundary layer. LES generally captures velocity field behind the cylinder successfully For this reason, in this study, LES analysis has been used for predicting upstream circular cylinder effect on the film cooling flow on the flat plate, which is discharged far downstream of the circular cylinder row
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