超超临界汽轮机合缸轴端漏汽量对中压第1级透平级冷却性能的影响

Effect of Shaft Seal Leakage on IP First-stage Steam Cooling Performance of an Ultra-supercritical HIP Combined Steam Turbine

采用耦合流场计算和共轭传热的方法,研究了超超临界汽轮机合缸轴端(过桥)汽封漏汽量(即轴端漏汽量)对中压第1级动叶及叶轮冷却性能的影响,对无蒸汽冷却、蒸汽冷却和轴端漏汽时中压第1级透平级的冷却性能进行了对比,并分析了3种轴端漏汽量时中压第1级透平级的冷却效果.结果表明:随着轴端漏汽量的增大,中压第1级透平级效率逐渐下降;当轴端漏汽量为9.68kg/s时,相比于无轴端漏汽时透平级效率降低了0.68%;轴端漏汽对中压第1级部件的冷却机理与冷却蒸汽相同,二者冷却效果的不同主要是由于其流量和温度不同;与蒸汽冷却相比,随着轴端漏汽量的增大,冷却蒸汽与轴端漏汽的混合蒸汽对叶根的冷却效果减弱,导致叶根温度整体上升,但温度梯度减小.

The effect of shaft seal leakage on intermediate-pressure （IP） first-stage steam cooling perform- ance of an ultra-supereritical high intermediate pressure （HIP） combined steam turbine was numerically investigated by coupled flow-field calculation and conjugated heat-transfer method, while the steam cooling characteristics were analyzed and compared respectively under no steam cooling, steam cooling and leakage steam cooling conditions. Results show that turbine stage efficiency at first stage of IP cylinder decreases with the rise of shaft leakage flow rate; for a shaft leakage flow rate of 9.68 kg/s, the turbine stage effi- ciency would be decreased by 0.68% in comparison with the zero leakage case; the cooling mechanism of leakage steam on the first-stage components is same as that of the cooling steam, and their cooling effects are different due to their different flow rates and temperatures; compared with the steam cooling condi- tion, the cooling effect on blade root by steam mixture from both shaft leakage and coolant flow weakens with the rise of leakage flow rate, resulting in increased temperature but reduced temperture gradient at blade root.