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ABSTRACT
The flow and heat transfer mechanisms of mist/air film cooling are studied in this paper with three hole types under three blowing ratios. The velocity vectors and three-dimensional contours of the vortices are shown in this paper in order to investigate the mist/air cooling characters with different hole types. Both the span averaged and centerline film cooling effectiveness are studied in this paper to compare the cooling performance of three cooling hole types.
Mist/air cooling performances of cylindrical hole, fan-shaped hole, and console hole are studied numerically. Flow structures of mist/air jets are studied. Both centerline and span averaged film cooling effectiveness are studied. Results show that the kidney vortex uplifts the mists further away from the flat plate and the antikidney vortex uplifts the mists near the lateral edge of the hole gradually. Mists enhancement on cooling effectiveness is significantly impaired at a higher blowing ratio in cylindrical hole and fan-shaped hole cases. The cooling effectiveness can maintain a relatively high value at each blowing ratio in console hole cases.
Nomenclature
| D | = | diameter of the film cooling hole inlet, m |
| d | = | diameter, m |
| l | = | slot width of the console hole exit, m |
| M | = | blowing ratio |
| P | = | pressure, Pa |
| Re | = | mainstream Reynolds number |
| T | = | temperature, K |
| Tu | = | turbulent intensity |
| TV | = | total vorticity value, 1/s2 |
| Uin | = | velocity at the mainstream inlet, m/s |
| vc | = | velocity of coolants, m/s |
| u | = | velocity component along the x direction, m/s |
| v | = | velocity component along the y direction, m/s |
| w | = | velocity component along the z direction, m/s |
| x | = | coordinate along the direction of the mainstream inlet velocity, m |
| y | = | coordinate along the span-wise or lateral direction, m |
| z | = | coordinate along the direction normal to the flat plate surface, m |
| η | = | adiabatic film cooling effectiveness |
| μ | = | dynamic viscosity, Pa/s |
| ρ | = | density, kg/m3 |
| Subscript | = | |
| av | = | span averaged value |
| aw | = | adiabatic wall |
| c | = | coolant |
| center | = | centerline value |
| console | = | console hole |
| cylindrical | = | cylindrical hole |
| fan | = | fan-shaped hole |
| main | = | mainstream |
| out | = | mainstream outlet |
| p | = | particle |
Nomenclature
| D | = | diameter of the film cooling hole inlet, m |
| d | = | diameter, m |
| l | = | slot width of the console hole exit, m |
| M | = | blowing ratio |
| P | = | pressure, Pa |
| Re | = | mainstream Reynolds number |
| T | = | temperature, K |
| Tu | = | turbulent intensity |
| TV | = | total vorticity value, 1/s2 |
| Uin | = | velocity at the mainstream inlet, m/s |
| vc | = | velocity of coolants, m/s |
| u | = | velocity component along the x direction, m/s |
| v | = | velocity component along the y direction, m/s |
| w | = | velocity component along the z direction, m/s |
| x | = | coordinate along the direction of the mainstream inlet velocity, m |
| y | = | coordinate along the span-wise or lateral direction, m |
| z | = | coordinate along the direction normal to the flat plate surface, m |
| η | = | adiabatic film cooling effectiveness |
| μ | = | dynamic viscosity, Pa/s |
| ρ | = | density, kg/m3 |
| Subscript | = | |
| av | = | span averaged value |
| aw | = | adiabatic wall |
| c | = | coolant |
| center | = | centerline value |
| console | = | console hole |
| cylindrical | = | cylindrical hole |
| fan | = | fan-shaped hole |
| main | = | mainstream |
| out | = | mainstream outlet |
| p | = | particle |