Mixed-flow water turbine runner blade outlet edge trimming method

A runner blade and blade outlet technology is applied in the field of edge trimming of the runner blade outlet of a Francis turbine, which can solve the problems such as the inability to prevent or eliminate the whistle of the turbine and the cracks of the runner blades, so as to avoid the generation of blade cracks and simplify the repair. Type technology, the effect of ensuring mechanical strength

Active Publication Date: 2018-10-16
DONGFANG ELECTRIC MACHINERY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The method disclosed in this patent document for alleviating the pressure pulsation hazard in the vaneless zone of the Francis pump turbine is proposed on the basis of the cause of the pressure pulsation in the vaneless zone. Prevent or eliminate the howling noise of the turbine and the cracks of the runner blades caused by the hydraulic elastic resonance of the blades induced by the Karman vortex street at the runner outlet

Method used

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  • Mixed-flow water turbine runner blade outlet edge trimming method
  • Mixed-flow water turbine runner blade outlet edge trimming method
  • Mixed-flow water turbine runner blade outlet edge trimming method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] A method for modifying the outlet edge of a Francis turbine runner blade, comprising the following steps:

[0035]a. Cut out the airfoil of the blade and determine the repair area of ​​the blade outlet side 1. The blade outlet side 1 includes an integrally formed upper section, a middle section and a lower section, and the length of the upper section and the lower section are both L 1 , L 1 It is 3% of the nominal diameter of the runner, the middle section is the trimmed area, the upper and lower sections are the non-profiled area, the transition between the profiled area and the non-profiled area is smooth, and the thickness of the outlet edge of the blade before the trimming is t 1 ;

[0036] b. Thickness of blade outlet edge after trimming is t 2 , the thickness of the outlet edge of the blade after modification is the thickness of the outlet edge of the blade before modification t 1 0.4 times of 0.4; the angle θ between the straight line segment in the blade fron...

Embodiment 2

[0043] A method for modifying the outlet edge of a Francis turbine runner blade, comprising the following steps:

[0044] a. Cut out the airfoil of the blade and determine the repair area of ​​the blade outlet side 1. The blade outlet side 1 includes an integrally formed upper section, a middle section and a lower section, and the length of the upper section and the lower section are both L 1 , L 1 It is 3.5% of the nominal diameter of the runner, the middle section is the trimmed area, the upper and lower sections are the non-modified area, the transition between the trimmed area and the non-modified area is smooth, and the thickness of the outlet edge of the blade before the trimming is t 1 ;

[0045] b. Thickness of blade outlet edge after trimming is t 2 , the thickness of the outlet edge of the blade after modification is the thickness of the outlet edge of the blade before modification t 1 0.45 times of 0.45 times; the angle θ between the straight line segment in the ...

Embodiment 3

[0053] A method for modifying the outlet edge of a Francis turbine runner blade, comprising the following steps:

[0054] a. Cut out the airfoil of the blade and determine the repair area of ​​the blade outlet side 1. The blade outlet side 1 includes an integrally formed upper section, a middle section and a lower section, and the length of the upper section and the lower section are both L 1 , L 1 It is 4% of the nominal diameter of the runner. The middle section is the trimmed area, and the upper and lower sections are non-profiled areas. There is a smooth transition between the trimmed area and the non-profiled area. The thickness of the outlet edge of the blade before the trimming is t 1 ;

[0055] b. Thickness of blade outlet edge after trimming is t 2 , the thickness of the outlet edge of the blade after modification is the thickness of the outlet edge of the blade before modification t 1 0.5 times of ; the angle θ between the straight line segment in the blade front ...

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Abstract

The invention discloses a mixed-flow water turbine runner blade outlet edge trimming method. The mixed-flow water turbine runner blade outlet edge trimming method comprises the following steps of: step a. cutting to obtain a blade wing profile, and determining a blade outlet edge trimming area; step b. enabling a molded line of the back of a blade after edge trimming and a molded line of the backof the blade before edge trimming to be in circular arc transition, wherein the radius R is 4-7 times of the thickness t1 of the outlet edge of the blade before edge trimming; step c. determining thefinal geometric dimension of the outlet edge trimming of the blade; step d. determining the sizes of a child-mother sample plate and a circular arc sample plate of the back of the blade, and integrally machining the child-mother sample plate and the circular arc sample plate of the back of the blade; step e. marking off on the outlet edge of the blade, and determining the final position of the back pressure edge of the outlet of the blade after trimming; step f. adjusting the angle of the outlet edge of the blade till the angle meets the size of the son-mother sample plate; and step g. grinding the circular arc of the black of the blade till the circular arc meets the size of the circular arc sample plate of the back of the blade. The mixed-flow water turbine runner blade outlet edge trimming method can prevent or eliminate water turbine squealing and blade cracks generated by blade hydraulic power elastic resonance induced by the Karman vortex street of a runner outlet, and improves the structure integrality of the mixed-flow water turbine runner and the operation safety of the water turbine.

Description

technical field [0001] The invention relates to the field of water turbines, in particular to a method for modifying the outlet edge of runner blades of a Francis water turbine. Background technique [0002] Among all the flow-induced vibration problems of Francis turbines, the resonance induced by the Karman vortex street at the outlet of the runner blades is a very destructive hydroelastic vibration. Once this kind of resonance occurs, there will be howling noise when the turbine is running, and it will cause large area cracks in the runner blades in a short time. The resonance induced by the Karman vortex street at the outlet of the Francis turbine runner blades usually appears in the operating area of ​​the runner with high flow velocity, that is, the high load operating area of ​​the Francis turbine. In addition, the frequency of howling is high, and the frequency of howling increases with the increase of turbine load. Therefore, in actual engineering, it is not diffi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F03B3/12F03B3/02F03B11/04B24B19/14
CPCB24B19/14F03B3/02F03B3/121F03B11/04Y02E10/20Y02P70/10
Inventor 石清华龚莉李国元
Owner DONGFANG ELECTRIC MACHINERY
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