有无叶顶冷却涡轮叶栅气热性能的旋转效应研究

为揭示叶片或机匣旋转条件和叶顶冷却对涡轮动叶气热性能的影响机理,选用LISA 1.5级涡轮动叶片,构建叶顶冷却孔,开展了不同冷气流量下的数值模拟研究。计算结果表明:不同旋转条件下,当冷气与主流的流量比为0.3%时,叶栅能量损失最低,当流量比为1.0%时,间隙泄漏流量最低、叶顶传热性能最好。叶片旋转、机匣旋转和平移运动都能降低泄漏损失和泄漏流量,叶片旋转时,叶栅出口下游上半叶高截面的能量损失最大降低约26.10%。旋转效应对泄漏损失的影响不随流量比变化而改变,但对叶栅总损失和叶顶传热品质的影响随流量比增加会不同。当流量比小于0.3%时,叶片旋转情况下叶栅总损失低于静止工况但高于机匣运动工况,且叶顶传热品质最优;当流量比大于0.7%时,叶片旋转使叶栅总损失最高,机匣运动使叶顶传热品质最优。

Study of Rotating Effects on Aero-thermal Performance of a Turbine Cascade With and Without Tip Cooling

In order to clarify the effects of blade or casing rotation and tip cooling on the aero-thermal performance of turbine rotors, numerical simulations are conducted for a rotor blade of LISA one-half-stage turbine. Cooling holes are generated on the blade tip, and various coolant mass flow rates are involved. Numerical results show that under different rotating conditions, the energy loss of the cascade is the lowest when the mass flow ratio of coolant to mainstream fluid equals 0.3%, while the tip leakage mass flow rate is the smallest and the tip heat transfer quality is the highest when the mass flow ratio equals 1.0%. Blade rotation, casing rotation and casing linear moving can decrease the tip leakage loss and leakage mass flow rate. The energy loss over the upper half span area downstream of the cascade outlet is reduced by a maximum value of 26.10% under the blade rotation. With the change in the mass flow ratio, rotating effects on the tip leakage loss are not varied, but those on the total loss and tip heat transfer quality are altered. When the mass flow ratio is lower than 0.3%, the rotating blade case has lower total loss than the stationary case but higher than casing moving case. This case also has the most favorable heat transfer quality. When the mass flow ratio is higher than 0.7%, the total loss is the largest for the blade rotation case, and the heat transfer quality is the best under the casing moving condition.