A saw-tooth plasma actuator for film cooling efficiency enhancement of a shaped hole

• Published in: Plasma science & technology Vol. 19; no. 8; pp. 125 - 137
• Main Author: 李国占 俞建阳 刘华坪 陈浮 宋彦萍
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2017
• Subjects: counter rotating vortex pair; film cooling; large eddy simulation; saw-tooth plasma actuator; shaped hole; 冷却效率; 大涡模拟; 强化; 形状; 气膜冷却; 激励器; 等离子体; 锯齿形
• ISSN: 1009-0630; 1009-0630
• DOI: 10.1088/2058-6272/aa6744

This paper reports the large eddy simulations of the effects of a saw-tooth plasma actuator and the laidback fan-shaped hole on the film cooling flow characteristics, and the numerical results are compared with a corresponding standard configuration（cylindrical hole without the sawtooth plasma actuator）. For this numerical research, the saw-tooth plasma actuator is installed just downstream of the cooling hole and a phenomenological plasma model is employed to provide the 3D plasma force vectors. The results show that thanks to the downward force and the momentum injection effect of the saw-tooth plasma actuator, the cold jet comes closer to the wall surface and extends further downstream. The saw-tooth plasma actuator also induces a new pair of vortex which weakens the strength of the counter-rotating vortex pair（CRVP） and entrains the coolant towards the wall, and thus the diffusion of the cold jet in the crossflow is suppressed.Furthermore, the laidback fan-shaped hole reduces the vertical jet velocity causing the disappearance of downstream spiral separation node vortices, this compensates for the deficiency of the saw-tooth plasma actuator. Both effects of the laidback fan-shaped hole and the saw-tooth plasma actuator effectively control the development of the CRVP whose size and strength are smaller than those of the anti-counter rotating vortex pair in the far field, thus the centerline and the spanwise-averaged film cooling efficiency are enhanced. The average film cooling efficiency is the biggest in the Fan-Dc=1 case, which is 80% bigger than that in the Fan-Dc=0 case and 288% bigger than that in the Cyl-Dc=0 case.