进口热斑存在时叶顶间隙对涡轮效率影响的数值计算

Numerical Simulation on the Effect of Tip Clearance on Efficiency of Turbine when Hot Streak Exist

利用非线性谐波法对某型燃气轮机2级涡轮进行了数值计算,对比研究了存在进口热斑时,叶顶间隙对带冠涡轮与不带冠涡轮气动效率的影响,并分析了带冠涡轮封严齿表面温度场分布受叶顶间隙影响的变化规律,与实验结果的对比验证了计算的可信性。研究发现:叶顶间隙小于0.24 mm时,不带冠涡轮具有更高的效率;带冠涡轮泄漏流一部分通过叶顶间隙流失,一部分受壁面剪切力作用形成涡团,以动能的形式耗散在叶冠容腔内;封严齿与机匣之间形成的高速射流与容腔内涡流相互作用,导致封严齿表面温度场分布不均;叶顶间隙为0.1 mm时,封严齿温度最高,在叶型设计改进时应重点考虑第一齿的冷却设计。所得结论可为涡轮叶片设计改型和进一步改进冷却方案提供理论依据和决策参考。

Nonlinear harmonic method（ NLH） was used for the calculation on gas turbine which has two stages. Comparative research on the aerodynamic efficiency of the gas turbine when hot streak exists was carried out. Effect of the shrouded blade tip clearance height on temperature of blade teeth was also analyzed. Research found that,when tip clearance height was below 0. 24 mm,the unshrouded type has higher efficiency. The leakage flow in the shrouded turbine can be divided in to two parts： one part will form the leakage vortex and the other part will be dissipated in the form of kinetic energy. The high speed leakage flow will interact with the vortex which will cause asymmetric temperature distribution of the blade teeth. The temperature will be highest when the clearance height was0. 1 mm. The first tooth of the blade will be paid much attention when improve the blade design. The acquired results can provide a theoretical basis for blade cooling design.