In search of improved cooling of gas turbine blades, the thermal performances of two different film cooling hole geometries (horn-shaped and cylindrical) are investigated in this numerical study. The horn-shaped hole is designed from a cylindrical hole by expanding the hole in the transverse direction to double the hole size at the exit. The two hole shapes are evaluated singly and in tandem. The tandem geometry assumes three configurations made by locating the cylindrical hole at three different positions relative to the horn-shaped hole such that their two axes remain parallel to one another. One has the cylindrical hole downstream from the center of the horn-shaped hole, a second has the cylindrical hole to the left of (as seen by the flow emerging from the horn-shaped hole) and at the same streamwise location as the horn-shaped hole (? = 90°) and the third has an intermediate geometry between those two geometries (downstream and to the left of the horn-shaped hole-? = 45°). It is shown from the simulation results that the cooling effectiveness values for the ? = 45° and 90° cases are much better than that for ? = 0° (the first case), and the configuration with ? = 45° exhibits the best cooling performance of the three tandem arrangements. These improvements are attributed to the interaction of vortices from the two different holes, which weakens the counter-rotating vortex pairs inherent to film cooling jet to freestream interaction, counteracts with the lift forces, enhances transverse tensile forces and, thus, enlarges the film coverage zone by widening the flow attachment region. Overall, this research reveals that integration of horn-shaped and cylindrical holes provides much better film cooling effectiveness than cases where two cylindrical film cooling holes are applied with the same tandem configuration.
|Original language||English (US)|
|Title of host publication||Aerospace Heat Transfer; Computational Heat Transfer; Education; Environmental Heat Transfer; Fire and Combustion Systems; Gas Turbine Heat Transfer; Heat Transfer in Electronic Equipment; Heat Transfer in Energy Systems|
|Publisher||American Society of Mechanical Engineers|
|State||Published - 2017|
|Event||ASME 2017 Heat Transfer Summer Conference, HT 2017 - Bellevue, United States|
Duration: Jul 9 2017 → Jul 12 2017
|Name||ASME 2017 Heat Transfer Summer Conference, HT 2017|
|Other||ASME 2017 Heat Transfer Summer Conference, HT 2017|
|Period||7/9/17 → 7/12/17|
Bibliographical noteFunding Information:
This work was supported by National Natural Science Foundation of China (51676163), by the Fundamental Research Funds of Shaanxi Province (2015KJXX-12), and by the Fundamental Research Funds for the Central Universities (3102015JCS05001).
Copyright © 2017 ASME.
- Blowing ratio
- Film cooling
- Horn-shaped hole
- Interaction of vortices