正攻角状态下尾迹对低压涡轮附面层的渗透及转捩的影响

Effects of Wakes on Penetration and Transition of Boundary Layer of Low-Pressure Turbine under Positive Incidence Condition

为研究正攻角状态下尾迹对低压涡轮附面层的渗透以及转捩过程的影响,分别在设计攻角和+10°攻角下,对高负荷低压涡轮叶型的吸力面附面层流动进行了数值模拟与实验。数值模拟使用CFX软件,采用大涡模拟模型。结果表明,在+10°攻角下,尾迹对附面层转捩过程的促进作用比设计攻角下更为显著,这是由于正攻角下的尾迹中心射流与吸力面切向的夹角更大,使得尾迹扰动渗透入附面层的深度更深,尾迹放大Klebanoff条纹强度更强,尾迹诱导转捩起始位置更靠上游。

In order to study the penetration of the upstream wakes into the boundary layer and the effect on transition of the boundary layer under positive incidence,the boundary layer on the suction surface of a highlyloaded low pressure turbine was investigated at design and +10° incidence conditions under numerical simulation and experiment. The simulations are performed with the CFX,by use of large eddy simulation(LES). It is found that the wakes play a greater role in promoting the transition of the boundary layer at +10° incidence than that at0° incidence. The turbulence of the wake under +10° incidence penetrate much deeper into the boundary layer due to the larger intersection angle between the direction of wake center and the tangent of the suction surface.Moreover,the intensity of the wake-amplified Klebanoff streaks is stronger,and the wake-induced transition onset is more upstream under +10° incidence.