Further increases in film-cooling effectiveness is a primary goal of the gas turbine industry. One effect that has been, for the most part, ignored in film-cooling studies, is the effect that a cross-flow at the hole entrance (which would occur on the internal side of the turbine blade) has on exiting jet and the cooling capabilities of that jet. This CFD study has investigated how different coolant flow directions at the inlet to either a round cooling hole or a shaped cooling hole can affect the overall cooling performance of that jet. The shaped cooling hole, which is fully expanded at 15°, had a lateral hole spacing of six hole diameters while the round hole had a lateral hole spacing of three hole diameters. Engine conditions were simulated in that a density ratio of two was used with a blowing ratio of M = 0.5 for the round hole and M = 1 for the shaped cooling hole. This allowed a direct comparison between the two geometries on the basis of equal coolant per blade pitch. The coolant supply flows at the hole entrance were considered to be either a plenum condition; parallel and in the same or opposite direction of the mainstream at the hole exit; or perpendicular to the mainstream at the hole exit. All of the flowing supplies had a channel Reynolds number of 30,000 and a channel height of 3 diameters. Results indicate that for the round cooling hole the adiabatic effectiveness values for a plenum and supply channel flow at 90° were essentially the same even though the flow features inside the coolant hole were significantly different. The adiabatic effectiveness for the shaped cooling hole, however, was significantly reduced when the coolant supply flow was perpendicular to the mainstream flow direction.
|Original language||English (US)|
|Number of pages||10|
|Journal||American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD|
|State||Published - Dec 1 1997|
All Science Journal Classification (ASJC) codes
- Mechanical Engineering
- Fluid Flow and Transfer Processes