Study on flow characteristics of leakage in the last stage inner blade tip clearance of steam turbine

Internal steam leakage in turbines from the high-pressure side to low-pressure through clearances causes loss, resulting reduced efficiency and potentially compromising safe operation of turbine. Therefore, a comprehensive understanding flow characteristics blade tip is crucial improve turbines. In this paper, last stage blades cylinder certain 600 MW ultra-supercritical turbine unit were studied. A wet model turbulence established, under different inlet parameters, outlet clearance sizes analyzed. The results showed that an increase size affects angles rotor blades, with significant changes occurring near tip. main velocity inside channel fluctuates violently starting 70% axial position. high entropy region located exit blade, its range expanding as increases. change at 60% height above, more intense area. relative amount uniformly variation. Generally, for every 0.1% height, increases by ∼0.31%–0.42%, decreases 0.34%–0.44%. study can provide theoretical basis guidance improving