| 主权项 |
1. A turbine assembly comprising a turbine blade and a casing, the casing surrounding the turbine blade and defining a gap therebetween, the turbine blade having a longitudinal axis, a suction side, a pressure side and a tip extending between the pressure and suction sides, wherein at least a portion of the tip comprises a shaped feature provided on a surface of the tip, the shaped feature having a first surface extending from the pressure side which is angled in a direction from the pressure side to the suction side with respect to a tangent at a free edge and with respect to a plane to which the longitudinal axis is normal to define a convergent portion configured to accelerate a flow over a portion of the tip in use from a subsonic speed to a transonic or a supersonic speed, wherein the shaped feature comprises a second surface angled up to 10° with respect to the plane to which the longitudinal axis is normal, wherein the shaped feature comprises a minimum tip gap between the shaped feature and the casing, and a remainder of the tip surface comprises a nominal tip gap between the remainder of the tip surface and the casing, the nominal tip gap being greater than the minimum tip gap, and wherein a ratio of the nominal tip gap to the minimum tip gap is 2:1. |
