Blade tip alula of turbine or steam turbine moving-blade

Abstract

The present invention provides a tip vane of guided vane of turbine or steam turbine related to field of turbomachine. The tip vane comprises a front edge wing, a pressure surface wing, a suction surface wing and a tail edge wing, the pressure surface wing and the suction surface wing are little vanes expended between front edge point A and tail edge point B of leaf along circumference, front edge point D and C of pressure surface wing and suction surface wing are lied on front edge point A or between front edge point A and most thickness part of guided vane; the tail edge point F and E of the pressure surface wing and the suction surface wing are arranged on tail edge point B or between tail edge point B and the most thickness part of guided vane; the front edge wing and tail edge wing are connected smoothly with the pressure surface wing and suction surface wing, and the front edge wing and the tail edge wing are extended parts of pressure surface wing and suction surface wing at front edge and tail edge. The present invention reduces effect of flow field in channel by tip leakage, tip leakage vortex and scraping gyres, improves cascade flow field, and enhances mechanical efficiency of impeller at the same time.

Description

technical field [0001] The invention relates to the field of turbomachinery, in particular to the design of tiplets applied to moving blades of various turbines or steam turbines. Background technique [0002] In turbomachinery, the geometric dimension of the tip clearance between the tip of the moving blade and the casing is very small compared with the entire flow path, but it affects the flow of nearly 20% of the blade flow path, especially Smaller turbines or steam turbines, etc. The blade tip clearance has the following adverse effects: 1) The existence of the blade tip clearance will reduce the actual flow of the working fluid, resulting in a decrease in work near the blade tip, channel blockage, and increased cascade loss; The suction surface of the blade forms the tip leakage vortex, and the interaction between the tip leakage vortex and the channel vortex makes the flow in the cascade channel more complicated, the flow loss increases, and the air outlet angle is ch...

AI Technical Summary

Problems solved by technology

The blade tip clearance has the following adverse effects: 1) The existence of the blade tip clearance will reduce the actual flow of the working fluid, resulting in a decrease in work near the blade tip, channel blockage, and increased cascade loss; The suction surface of the blade forms the tip leakage vortex, and the interaction between the tip leakage vortex and the channel vortex makes the flow in the cascade channel more complicated, the flow loss increases, and the air outlet angle is changed at the same time; 3) Since the rotor moves relative to the casing wall, Cause the frictional movement of the boundary layer on the casing wall, forming a friction vortex

The three effects brought by the tip clearance all change the distribution of the flow field in the turbomachinery to varying degrees and increase the flow loss in the turbomachinery

The flow loss caused by the blade tip clearance and the secondary flow loss such as the blade tip leakage vortex and the blade tip friction vortex generally account for a considerable proportion of the total loss of the turbomachinery, resulting in an increase in the total loss of the turbomachinery

If the existing blade shroud is used, the blade shroud and the outer casing need to adopt a multiple sealing system, and the blade shroud rotates at high speed, and the centrifugal force is large, which will increase the stress of the moving blade, thereby reducing the reliability of the turbomachinery to a certain extent

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