http://orcid.org/0000-0002-6068-0891
![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
Air film cooling is a conventional cooling technique that has been successfully used for gas turbine hot-section components, such as combustor liners, combustor transition pieces, and turbine vanes and blades. However, the increased benefit seems to approach a limit. This paper investigates the film cooling effectiveness considering mist injection. All the studies for various boundary conditions are conducted numerically, including the effects of droplet size, the flow rates of droplet injection, and the coolant air. Film cooling is also affected by the interaction between deposition and mist injection. A deposition configuration is located near the film hole with an inclination angle of 35°. Results show that the combined effect of injection and deposition is to weaken the film cooling effectiveness, especially upstream of x/d = 19. For the coolant air at a low speed, the mist injection cannot provide better cooling protection than without the mist injection.
Nomenclature
| c | = | deposition location (distance), m |
| d | = | film hole throat diameter, m |
| Deff | = | effective diffusion coefficient, m2/s |
| Dp | = | diameter of droplets, m |
| 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 | = | stream-wise velocity component, m/s |
| V | = | velocity magnitude, m/s |
| w | = | width of deposition, m |
| x, y, z | = | coordinates, m |
| Greek symbols | = | |
| 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) |
| θ | = | density, kg/m3 |
| τ | = | stress tensor, N/m2 |
| Subscripts | = | |
| air | = | air film cooling (cases without mist injection) |
| aw | = | adiabatic wall |
| i | = | mainstream flow |
| j | = | coolant jet |
| mist | = | mist film cooling (cases with mist injection) |
| t | = | turbulent |
| Superscripts | = | |
| ’ | = | pulsating component |
Nomenclature
| c | = | deposition location (distance), m |
| d | = | film hole throat diameter, m |
| Deff | = | effective diffusion coefficient, m2/s |
| Dp | = | diameter of droplets, m |
| 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 | = | stream-wise velocity component, m/s |
| V | = | velocity magnitude, m/s |
| w | = | width of deposition, m |
| x, y, z | = | coordinates, m |
| Greek symbols | = | |
| 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) |
| θ | = | density, kg/m3 |
| τ | = | stress tensor, N/m2 |
| Subscripts | = | |
| air | = | air film cooling (cases without mist injection) |
| aw | = | adiabatic wall |
| i | = | mainstream flow |
| j | = | coolant jet |
| mist | = | mist film cooling (cases with mist injection) |
| t | = | turbulent |
| Superscripts | = | |
| ’ | = | pulsating component |