二次流动对气冷涡轮叶栅流场的影响

Effect of the secondary flow on the film cooling turbine cascade

关键词:  气膜冷却  二次流动  边界层转捩  相互作用  数值仿真

Key words:  Film-cooling  Secondary flow  Boundary layer transition  Interaction  Numerical simulation

摘要:

针对典型跨声速高压涡轮叶型平面叶栅吸力面单排孔气膜冷却,采用数值模拟方法,比较分析了加入气膜冷却前后流场变化。结果表明,由于二次流动的影响,加入气膜冷却以后吸力面后部接近下壁面处没有受到冷气保护而直接暴露于主流高温燃气,在实际高压涡轮中将极大的降低叶片寿命。没有气膜冷却情况下,吸力面接近下壁面处边界层仍有可能因受到二次流动的影响发生转捩;加入气膜冷却情况下,气膜孔中心位置下游边界层由于射流和主流的相互作用将转变为湍流边界层,而由于孔间距的影响,只有射流和主流充分掺混以后才能影响到整个叶片的范围。

Abstract:

Presented the influence of the secondary flow to the suction side sigle row film cooling with numerical simulation.The results indicate that the rear part of the sunciton side near the end wall suffers from the main flow high temperature gas because of the secondary flow and the film cooling has no effect in this aera.In the condition without film cooling,the secondary flow will trigger the boundary lay transition on the suction side near the end wall.The boundary layer downstream of the cooling hole can also be triggered by the interaction between the main flow and the cooling jet.