燃气轮机涡轮动叶顶部气动与传热特性的数值研究

Numerical investigation on aerodynamic performance and heat transfer of rotor tip in gas turbine

应用SSTκ-ω湍流模型并结合SIMPLEC算法,对燃气轮机涡轮动叶叶顶间隙及通道冷却流场进行数值模拟。通过在叶顶靠近吸力面侧、压力面侧以及中弧线位置处设置冷却孔排,研究不同孔排布置对叶顶气动性能及气膜冷却效果的影响。结果表明:冷却喷气有效削弱了叶顶间隙泄漏损失,降低了泄漏涡对叶栅出口截面气动损失的影响;在肩壁的作用下泄漏流形成了分离涡,涡流的移动强化了叶顶的传热和冷却效果,增强了壁面与泄漏流之间的对流换热,同时在靠近上端壁和沿着流道轴向方向形成均匀的压力梯度;叶顶孔排有效地组织了二次流并减小了叶顶表面的温度梯度和叶栅通道下游的气动损失,但对整个叶栅通道气动性能的改变影响较小。

With the SST k-ωturbulent model,SIMPLEC algorithm was adopted to study the aerodynamic performance of the blade tip by establishing three numerical models of the turbine rotor blade with three kinds of squealer tips,the holes close to the suction side,the pressure side and the position of the middle line respectively to further understand the effects of aerodynamic performance and the heat transfer charac-teristic with different structures of the tip and study the distribution of the tip film cooling effectiveness.The results show the jet flow can effectively reduce the leakage flow and weaken the effect from the clearance flow on aerodynamic performance.The leakage flow in the tip clearance under the effect of the shoulder wall forms separation vortex which have a great impact on the heat transfer characteristic and film cooling performance of the tip and strengthen the heat convection between the wall and the leakage flow,the vortex near the upper endwall and along the axial chord forms uniform pressure gradient.The holes on the tip effec-tively organize the secondary flow which decreases the temperature gradient on the tip surface and the aero-dynamic performance loss the downstream of the cascade,but less effect on the change of the aerodynamic performance of all cascade.