不同叶尖间隙下的涡轮转子出口 三维流场测量

采用圆锥四孔高频压力探针测量了某涡轮不同叶尖间隙下转子出口的三维时均流场.结果表明转子出口参数均呈现明显的周期特性.叶尖间隙对转子出口流动品质有较大影响;间隙大时,泄漏流显著,对应的机匣二次流动较弱;间隙小时,机匣附近的二次流动较强.泄漏流区域的速度低,对应的相对总压小,损失大;泄漏流导致气流亏转,对应的静压高,膨胀程度小于主流,增大间隙,膨胀比变小,涡轮做功能力下降. 

Measurements of three-dimensional flow field at exit of a turbine rotor passage in different tip clearances

The time-resolved flow field downstream of a turbine rotor with different tip clearances was measured using a fast-response four-hole pressure probe.The results show that the flow is obviously periodic due to the rotor.It also indicates that the tip leakage flow has profound effects on the flow field.With bigger tip clearance,the leakage flow is relatively stronger and the secondary flow near the casing wall is weaker.When the tip gap is smaller,the secondary flow near the casing wall becomes stronger.The velocity in the leakage flow region is very low and the loss is high,which leads to substantial flow blockage.The flow under-turning due to the leakage flow is also clearly seen in the measurements.The static pressure in the leakage flow is higher than that in the main flow.The work done by the rotor with bigger tip clearance is lower than that with smaller tip clearance.