The augmentation of internal tip heat transfer in gas turbine blades using a pair of delta-winglet vortex generators

A novel method to enhance the heat transfer on the internal tip surface of gas turbine blades was developed. Effects of delta-winglet vortex generators (DWVG) and their angle of attack on the vortical structures and mechanism of enhanced heat transfer were investigated. Seven different angles of attack were considered: 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The Reynolds number varies from 10,000 to 50,000. Flow topology analysis was employed to better understand the evolution of vortices in the turn region. Results showed that a vortex was induced on the leeward side of the DWVG as the angle of attack was greater than 0°, which significantly enhanced the local heat transfer. Also, an extra saddle point was generated at the tip surface on the windward side of the DWVG as the angle of attack is greater than 45°, indicating that a vortex wass formed. The internal tip heat transfer increased as the angle of attack of the DWVG increased. The optimal design was reached when the angle of attack is greater than 60°. Compared with the smooth channel, the heat transfer and overall thermal performance are enhanced by up to 9.5% and 8.1%, respectively.