用气膜冷却来防止热斑引起的涡轮叶片过热

Using film cooling to keep the turbine blades from overheat induced by hot streaks

关键词:  涡轮叶片  热斑+  非定常流  薄膜冷却  数值仿真

Key words:  Turbine blade  Hot streak~+  Unsteady  Film cooling  Numerical simulation

摘要:

为了防止燃烧室出口热斑引起涡轮叶片过热,通过求解二维非定常N-S方程研究了热斑对高压涡轮一级叶片型面压力和温度的非定常影响,并对气膜冷却这种热防护方法进行了尝试。计算结果与公开发表的实验数据基本吻合。结果显示热斑的存在对涡轮级型面压力影响微小,但是会导致动叶型面特别是压力面的温度显著升高并随时间大幅波动。在动叶压力面鳃区引入气膜冷却对型面压力和热斑在涡轮级内的运动影响不大,但可以有效地阻隔高温热斑与压力面的直接接触,并显著降低壁温和减小温度随时间波动的幅度。

Abstract:

To prevent the turbine blades from overheat induced by combustor hot streaks,two-dimensional unsteady Navier-Stokes simulations were performed on a typical high-pressure turbine stage to study the effects of hot streaks on the airfoils surface pressure and temperature.Such measure as film cooling was tried to protect the turbine blades from overheat caused by hot streaks.Numerical results are consistent well with the available experimental data in open literature.The results show that the existence of hot streaks have little effect on the blades surface pressure,but will lead to time-averaged surface temperature increase on rotor blades especially on pressure surface and augmentation of temperature unsteadiness.Injecting coolants at the gill region on rotor pressure surface have small influence on the blade surface pressure and the migration of hot streaks in turbine stage,but can prevent the hot spots from direct impact on pressure surface to decrease the time-averaged and the fluctuation of surface temperature.