Abstract
The influence of film-hole position on internal and external heat transfer was investigated using Computational Fluid Dynamics (CFD). A simplified geometry of an integrated configuration of a ribbed channel, film hole and mainstream passage is modeled to represent a turbine internal and external cooling scheme. The proposed configurations with nine different positions of film holes are parameterized to conduct a series of CFD calculations at a target blowing ratio of 0.8, 1.1 and 1.7. Since the present study is taking a comparative approach, CFX with SST models is applied as a primary tool and the results are compared with Fluent solver for selected cases (total 36 cases). Among the proposed nine positions, the film holes located in the separated flow region of a ribbed channel showed considerable enhancement in film effectiveness with minimum reduction and potential improvement in internal heat transfer. The finding offers a design opportunity to enhance internal as well as external heat transfer.
Highlights
Since cooled turbine airfoil was introduced for gas turbine application, there is a continuous effort to improve the performance of film cooling
The previous studies focused only on film performance or the internal heat transfer of a ribbed internal cooling channel, the present study aims to evaluate the influence of film-hole location on internal as well as external heat transfer
The boundary condition of the inlet of the ribbed cooling channel is adjusted to achieve target blowing ratios (0.8, 1.1 and 1.7) of the film hole positioned at DP00 while the boundary condition of the mainstream flow is fixed
Summary
Since cooled turbine airfoil was introduced for gas turbine application, there is a continuous effort to improve the performance of film cooling. For BR = 2.0, the highest values were shown when the film hole was positioned in the downstream of the rib [11] In another experimental study [12] on the configuration of a 60◦ rib with three film positions (downstream, middle and upstream of the rib), the regional average effectiveness increased as blowing ratio increased (BR = 0.4~0.8). The flow control parameters for internal and external heat transfer are (1) blowing ratio of film and (2) Reynolds number of ribbed cooling channels. For this purpose, a parametric geometry was produced for conducting the series of mesh generation and analysis. Additional studies on the sensitivity of mesh density, RANS solver and the turbulent model were conducted to demonstrate the validity of the computational approach for the present study
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