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ABSTRACT
In the present paper, numerical analysis has been performed to investigate the film-cooling performance of a cylindrical hole, cylindrical hole with upstream parallel auxiliary holes, cylindrical hole with downstream parallel auxiliary holes, and a cylindrical hole with both upstream and downstream parallel auxiliary holes. Four kinds of film-cooling holes are compared through Reynolds-averaged Navier–Stokes (RANS) analysis for four blowing ratios: 0.5, 1.0, 1.5, and 2.0. The result shows that the auxiliary holes enhance the film-cooling effectiveness. The cylindrical hole with upstream auxiliary holes is better for protecting the text surface than the cylindrical hole with downstream auxiliary holes. In general, the hole with both upstream and downstream parallel auxiliary holes shows the most effective film protection compared with the other three cases tested in this work, especially in blow ratios 0.5 and 1.0.
Nomenclature
| D | = | film-cooling hole diameter |
| Eg | = | heat transfer coefficient ratio |
| h | = | local heat transfer coefficient with film cooling |
| h0 | = | heat transfer coefficient without film-cooling holes |
| M | = | blow ratio: M = ρjuj/ρ∞u∞ |
| q | = | heat flux constant |
| Re | = | Reynolds number |
| T | = | temperature (K) |
| u | = | velocity (m/s) |
| x | = | coordinate in the stream-wise direction |
| y | = | coordinate normal to the test surface |
| y+ | = | the normalized distance |
| z | = | coordinate in the lateral direction |
| α | = | injection angle of film-cooling hole |
| ρ | = | density (kg/m3) |
| η | = | film-cooling effectiveness |
| Θ | = | cooling effectiveness |
| Subscripts | = | |
| aw | = | adiabatic wall |
| j | = | coolant jet |
| ∞ | = | main stream |
| s | = | spatially averaged value |
Nomenclature
| D | = | film-cooling hole diameter |
| Eg | = | heat transfer coefficient ratio |
| h | = | local heat transfer coefficient with film cooling |
| h0 | = | heat transfer coefficient without film-cooling holes |
| M | = | blow ratio: M = ρjuj/ρ∞u∞ |
| q | = | heat flux constant |
| Re | = | Reynolds number |
| T | = | temperature (K) |
| u | = | velocity (m/s) |
| x | = | coordinate in the stream-wise direction |
| y | = | coordinate normal to the test surface |
| y+ | = | the normalized distance |
| z | = | coordinate in the lateral direction |
| α | = | injection angle of film-cooling hole |
| ρ | = | density (kg/m3) |
| η | = | film-cooling effectiveness |
| Θ | = | cooling effectiveness |
| Subscripts | = | |
| aw | = | adiabatic wall |
| j | = | coolant jet |
| ∞ | = | main stream |
| s | = | spatially averaged value |