Investigations of Film Cooling Effect on Squealer Tip with Plasma Actuation

Film cooling performance on a gas turbine squealer tip was numerically investigated by incorporating plasma actuation forces into the momentum equations of Reynolds-averaged Navier-Stokes equations. The objective was to analyze the impact of plasma actuation strength and actuation frequency on the film cooling effectiveness and total pressure loss in tip region. Furthermore, a plasma control strategy was proposed to improve the coolant coverage on the cavity floor of squealer tip, and the mechanism of plasma actuation on the coolant and mainstream in the tip gap was elucidated. The results showed that the downstream plasma actuation within the squealer cavity effectively counteracts the swirling effect provided by the upstream coolant to the downstream coolant. Such resistant effect is increased with increasing the actuation strength and actuation frequency. When the plasma actuation is minimal, the upstream coolant provides little swirling effect to the downstream coolant in squealer cavity, resulting in effective film cooling effect on the cavity floor near trailing edge. As the actuation strength increases, the coolant near the trailing edge is blown away from the cavity floor by the upstream coolant, but the film cooling effect on the central part of cavity floor becomes better. Compared to the no actuation case, the area-averaged film cooling effectiveness on the cavity floor of squealer tip is increased by 25. 11 % for actuation strength Ds = 204. The actuation frequency displays a similar effect on the film cooling at squealer tip as the actuation strength. If the actuation strength is fixed at Ds = 156, the area-averaged film cooling effectiveness on the cavity floor is increased by 28. 71 % for actuation frequency D9 = 6. 25 and actuation frequency 29. 27% respectively as compared to the no actuation case. Additionally, non-uniform plasma actuation on the squealer tip leads to a 39. 12% increase in the area-averaged film cooling effectiveness on the cavity floor compared to the no actuation case. Notably, the total pressure loss in the rotor blade is almost unchanged with the specified plasma excitation. © 2024 Xi'an Jiaotong University. All rights reserved.