Abstract:

In order to reduce the tip leakage loss, a pressure correction based, 3D Reynoldsaveraged Navier-Stokes equations CFD code with Reynolds stress model and wall function is used to simulate the effects of the passive control of an improved tip of a pressure side tip shelf with vertical squealer tip on the tip leakage flow in a turbine rotor. With different shelf heights and depths in an improved tip, the effect on the tip leakage flow, especially on the efficiency, is sequentially simulated and compared with the baseline flow field with a flat tip. The results show that the recirculation region appearing in the tip region and the inclined shelf near pressure side can block the tip leakage flow in the effect of an improved tip, then the turbine efficiency increases. The height of tip platform shelf has more effect on the turbine efficiency, and the shelf height has an optimal value, where the turbine efficiency can increase by 0.215%.The shelf depth has less effect on the flow field, and the turbine efficiency slightly increases when the shelf depth is small.

Key words: tip clearance height, tip leakage vortex, squealer tip, passive control, numerical simulation