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ABSTRACT
The adiabatic film-cooling effectiveness on a thermal barrier coating surface is investigated numerically. A film-cooling hole with an inclination angle of 35° is placed upstream the deposition configuration. The depositions are arranged on the external wall with three different positions. For no-mist models, the cooling performances downstream the wall are investigated for the blowing ratios of 0.5, 0.75, and 1.0. Results show that the adiabatic film-cooling effectiveness without surface deposition is decreased by increasing the blowing ratio. To investigate the effects of both different locations and 4.4% mist injection on the film cooling, a discrete phase model (DPM) is used. It is found that the film-cooling effectiveness is improved remarkably from the deposition position to the wall downstream. In addition, deposition formation at the middle location shows a good cooling effectiveness, but the lowest value of the film-cooling effectiveness occurs upstream the deposition position.
Nomenclature
| c | = | deposition location (distance), m |
| d | = | film hole throat diameter, m |
| Deff | = | effective diffusion coefficient |
| h | = | height of deposition, m |
| k | = | turbulence kinetic energy, m2/s2 |
| M | = | blowing ratio, =ρjVj/ρ∞V∞ |
| P | = | pressure, N/m2 |
| S. F | = | source term |
| T | = | temperature, K |
| u | = | streamwise velocity component, m/s |
| V | = | velocity magnitude, m/s |
| w | = | width of deposition, m |
| x, y, z | = | coordinate direction distance, m |
| α | = | inclination angle, deg |
| ϵ | = | turbulence dissipation rate, m2/s3 |
| η | = | adiabatic film-cooling effectiveness, = (Taw–Ti)/(Tj–Ti) |
| λ | = | thermal conductivity, W/m K |
| θ | = | nondimensional temperature, = (T–Ti)/(Tj–Ti) |
| ρ | = | density, kg/m3 |
| τ | = | stress tensor, N/m2 |
| Subscripts | = | |
| a | = | area average value |
| aw | = | adiabatic wall |
| c | = | centerline |
| i | = | mainstream flow |
| j | = | coolant jet |
| t | = | turbulent |
Nomenclature
| c | = | deposition location (distance), m |
| d | = | film hole throat diameter, m |
| Deff | = | effective diffusion coefficient |
| h | = | height of deposition, m |
| k | = | turbulence kinetic energy, m2/s2 |
| M | = | blowing ratio, =ρjVj/ρ∞V∞ |
| P | = | pressure, N/m2 |
| S. F | = | source term |
| T | = | temperature, K |
| u | = | streamwise velocity component, m/s |
| V | = | velocity magnitude, m/s |
| w | = | width of deposition, m |
| x, y, z | = | coordinate direction distance, m |
| α | = | inclination angle, deg |
| ϵ | = | turbulence dissipation rate, m2/s3 |
| η | = | adiabatic film-cooling effectiveness, = (Taw–Ti)/(Tj–Ti) |
| λ | = | thermal conductivity, W/m K |
| θ | = | nondimensional temperature, = (T–Ti)/(Tj–Ti) |
| ρ | = | density, kg/m3 |
| τ | = | stress tensor, N/m2 |
| Subscripts | = | |
| a | = | area average value |
| aw | = | adiabatic wall |
| c | = | centerline |
| i | = | mainstream flow |
| j | = | coolant jet |
| t | = | turbulent |