涡轮叶片叶顶间隙变化减敏研究

采用数值方法联合标准k-ω两方程湍流模型求解雷诺平均Navier-Stokes方程组,研究了平顶和分别采用被动、主动以及复合间隙控制方法的凹槽顶、平顶喷气、凹槽顶喷气4种不同叶顶结构下涡轮性能对叶顶间隙变化的敏感性,分析了间隙变化对间隙流场结构及损失的影响,研究了涡轮性能随叶顶间隙变化的规律,并对采用不同间隙控制方法的叶顶结构所带来的效率收益对攻角变化敏感性进行了评估.结果表明:在不同间隙控制方法下叶顶泄漏涡强度随间隙的增加速度变缓,尤其在复合间隙控制方法下更为明显,从而使得在复合间隙控制方法下涡轮性能对间隙变化的敏感度最低;仅仅涡轮叶片前缘区域泄漏流动对攻角变化比较敏感,使得凹槽顶结构具有最佳的攻角变化适应性. 

Investigations on desensitization of blade tip clearance variation in turbine blades

Numerical investigation was performed to simulate the sensitivity of turbine performance to blade tip clearance variation for four different tips including flat tip and other three tips: cavity tip, flat tip with injection and cavity tip with injection; passive, active and compound clearance control methods were used respectively by solving Reynolds-averaged Navier-Stokes equations in conjunction with a standard k-ω two-equation turbulence model. The influences on the clearance flow structure and losses caused by tip clearance variation were analyzed. In addition, the variation of the turbine performance which changes by the different clearances was investigated. Furthermore, the sensitivities of the efficiency-gains caused by different clearance control methods to changes in incidence angles were assessed. Results show that, with different clearance control methods, the growth rate of the strength of tip leakage vortex slows down, especially for the compound clearance control method. This leads to the results that the compound clearance control method presents the lowest sensitivity of turbine performance to clearance variation. In addition, only the leakage flows over the front part of the blade are sensitive to incidence angle variation, which causes the best adaptability of cavity tip to incidence angle variation.