Y-shaped wing-shaped baffle plate capable of inhibiting power fluctuation of vortex strip region and use method

Abstract

The invention belongs to the technical field of draft tubes of water turbines, and particularly relates to a Y-shaped wing-shaped baffle capable of restraining power fluctuation of a vortex zone and a using method of the Y-shaped wing-shaped baffle. According to the technical scheme, the Y-shaped wing-shaped baffle capable of restraining the power fluctuation of the vortex strip area comprises a bottom branch, one side of the bottom branch is connected to the inner wall of a draft tube, two suspension branches are fixed to the other side of the bottom branch, and the included angle between the bottom branch and the suspension branches is larger than 120 degrees. The invention provides a Y-shaped wing-shaped baffle capable of restraining power fluctuation of a vortex strip area and a using method. The problem that when a water turbine is started to run and passes through the vortex strip area, a cavitation vortex strip of a draft tube causes violent power low-frequency oscillation is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water turbine draft tube, and particularly relates to a Y-shaped airfoil baffle capable of inhibiting power fluctuation in vortex zone and a use method. BACKGROUND

[0002] The water turbine is a power machine for converting kinetic energy of water flow into rotary mechanical energy, and belongs to the turbine machine in fluid machinery. Most of the modern water turbines are installed in hydropower stations to drive power generation equipment. The counterattack water turbine is provided with a draft tube, which is a bend pipe (also known as a diffuser) with an increasing cross-sectional area, and functions to discharge the water flow at the outlet of the runner to the downstream and recover the energy of a part of the water flow at the outlet of the runner to fully utilize the potential energy of the water flow.

[0003] When the water turbine starts to run through the vortex zone, vortex flow appears downstream of the runner and induces eccentric vortex zone. The vortex zone usually evolves into cavitation vortex zone to cause severe power low-frequency oscillation, which seriously affects the safe operation and stability of the water turbine unit in the hydropower station. The measures for relieving the problem in engineering mainly include three types: 1) optimizing the runner to widen the stable operation range (such as patents CN201133321, CN1530538 and CN1499073); 2) inhibiting low-frequency pulsation by jet flow (water supplement, air supplement, etc.) (such as patents CN101501329, CN200975311 and CN101975132A); and 3) installing a flow stabilizing device to destroy the vortex zone structure (such as patents CN1740556, CN1702317 and CN202140227U).

[0004] Details of the prior art: 1) structural components: the counterattack water turbine mainly includes a runner and a draft tube; 2) positional relationship between the components: the draft tube is connected downstream of the runner to receive the water flow at the outlet of the runner; 3) functions of the components: the runner converts kinetic energy of water flow into rotary mechanical energy, and the draft tube realizes water discharge and energy recovery; 4) whole working process: water flow drives the runner to rotate → the water flow at the outlet of the runner enters the draft tube → the water flow in the draft tube decreases in flow rate and increases in pressure to form an inverse pressure field (vortex zone) → the vortex zone induces power fluctuation. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the purpose of the present application is to provide a Y-shaped airfoil baffle capable of inhibiting power fluctuation in vortex zone and a use method, so as to solve the problem of severe power low-frequency oscillation caused by cavitation vortex zone in the draft tube when the water turbine starts to run through the vortex zone.

[0006] The technical scheme adopted by the present application is as follows: A Y-shaped airfoil baffle capable of inhibiting power fluctuation in vortex zone, comprising a bottom branch, one side of the bottom branch being connected to the inner wall of a draft tube, and the other side of the bottom branch being fixed with two hanging branches, and the included angle between the bottom branch and the hanging branches being greater than 120°.

[0007] This invention only adds components inside the tailrace pipe, leaving the rest of the pipe unaffected. Furthermore, the Y-shaped airfoil baffle can be designed after the entire runner design is completed. During manufacturing, only the corresponding slot for the Y-shaped airfoil baffle needs to be added inside the tailrace pipe, and the Y-shaped airfoil baffle itself needs to be manufactured. Different Y-shaped airfoil baffles can also be added depending on the specific operating conditions.

[0008] When the water flow into the turbine's vortex belt, the Y-shaped airfoil baffle installed in the draft tube begins to function. The bottom branch connects to the inner wall of the draft tube, directly disrupting the vortex belt's rotational structure. Simultaneously, two suspended branches cut into the core rotational region of the vortex belt, their upstream surfaces colliding with the swirling flow to generate a backflow that neutralizes the swirling flow in the middle of the draft tube, effectively reducing the circumferential water velocity. The synergistic effect of these two aspects significantly reduces the intensity and size of the draft tube vortex belt, thereby mitigating low-frequency power oscillations.

[0009] As a preferred embodiment of the present invention, the cross-section of the suspended branch is arc-shaped, and the suspended branch smoothly transitions to the bottom branch. The arc-shaped suspended branch can cut into the rotating core region of the vortex belt, and its upstream surface collides with the swirling flow.

[0010] As a preferred embodiment of the present invention, the suspended branch bends away from the other suspended branch.

[0011] As a preferred embodiment of the present invention, the bottom branch is connected to the inner wall of the straight conical section of the tailrace pipe, and the Y-shaped airfoil baffle is close to the upper end face of the tailrace pipe. This position precisely corresponds to the core area where the vortex belt is generated, and can directly act on the vortex and vortex belt, thus solving the problem of limited intervention effect in non-core areas in the prior art.

[0012] As a preferred embodiment of the present invention, the width D1 of the bottom branch along the radial direction of the tailwater pipe satisfies: 0.45R≤D1≤0.55R; where R is the inlet radius of the tailwater pipe.

[0013] As a preferred embodiment of the present invention, in a cross section perpendicular to the tailpipe, the ratio of the width D2 of the cantilever branch to the width D1 of the bottom branch satisfies: 0.5≤D2 / D1≤1.

[0014] As a preferred embodiment of the present invention, the length L1 of the bottom branch along the axial direction of the tailwater pipe satisfies: L1 < L0; where L0 is the length of the straight conical section of the tailwater pipe.

[0015] As a preferred embodiment of the present invention, the end faces of the bottom branch and the cantilever branch are perpendicular to the axis of the tailwater pipe.

[0016] The aforementioned size constraints ensure that the Y-shaped airfoil baffle is compatible with the tailrace structure without generating additional hydraulic losses, while also guaranteeing the vortex suppression effect.

[0017] As a preferred embodiment of the present invention, the inner wall of the straight conical section of the tailrace pipe is provided with a groove, and one side of the bottom branch is detachably connected to the groove. The Y-shaped airfoil baffle is detachably installed through the groove pre-set on the inner wall of the straight conical section of the tailrace pipe, and the installation / removal state can be freely switched according to whether the turbine has entered the vortex zone, so as to meet the operating requirements under different working conditions and improve the equipment adaptability.

[0018] A method for using a Y-shaped airfoil baffle that suppresses power fluctuations in the vortex zone includes the following steps: S1: Determine the environment for starting and operating the turbine runner; if the startup process will enter the vortex zone, proceed to step S2; otherwise, proceed to step S3. S2: When starting and entering the vortex zone, install the Y-shaped airfoil baffle inside the tailrace pipe, start the turbine runner, and the bottom branch collides with the swirling flow to generate a reverse jet, and the suspended branch destroys the rotating structure of the vortex zone. S3: When starting without entering the vortex zone, remove the Y-shaped airfoil baffle from the draft tube and then start the turbine runner.

[0019] The beneficial effects of this invention are as follows: 1. When the water flow into the turbine's vortex belt, the Y-shaped airfoil baffle installed in the draft tube begins to operate. The bottom branch connects to the inner wall of the draft tube, directly disrupting the vortex belt's rotational structure. Simultaneously, two suspended branches cut into the core rotational region of the vortex belt, their upstream surfaces colliding with the swirling flow to generate a backflow that neutralizes the swirling flow in the middle of the draft tube, effectively reducing the circumferential water flow velocity. The synergistic effect of these two aspects significantly reduces the intensity and size of the draft tube vortex belt, thereby mitigating low-frequency power oscillations.

[0020] 2. This invention only adds components inside the tailrace pipe, while the rest of the pipe remains unaffected. Furthermore, the Y-shaped airfoil baffle can be designed after the entire impeller design is completed. During manufacturing, only a corresponding slot for the Y-shaped airfoil baffle needs to be added inside the tailrace pipe, and the Y-shaped airfoil baffle itself needs to be manufactured. Different Y-shaped airfoil baffles can also be added depending on the specific operating conditions. Attached Figure Description

[0021] Fig. 1 This is an assembly drawing of the present invention; Fig. 2 This is a schematic diagram of the structure of the present invention; Fig. 3 This is the front view of the present invention.

[0022] In the diagram: 1-bottom branch; 2-hanging branch; 3-tailwater pipe. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0025] like Figs. 1-3 As shown, the Y-shaped airfoil baffle with power fluctuation suppression in the vortex zone of this embodiment includes a bottom branch 1. One side of the bottom branch 1 is connected to the inner wall of the draft tube 3, and two suspended branches 2 are fixed to the other side of the bottom branch 1. The included angle between the bottom branch 1 and the suspended branches 2 is greater than 120°. The bottom branch 1 and the two suspended branches 2 of the Y-shaped airfoil baffle are both hydrofoils, which reduces the hydraulic loss of the turbine.

[0026] Furthermore, the cross-section of the suspended branch 2 is arc-shaped, and the suspended branch 2 smoothly transitions with the bottom branch 1. The arc-shaped suspended branch 2 can cut into the rotating core region of the vortex belt, and its upstream surface collides with the swirling flow.

[0027] The suspended branch 2 bends away from the other suspended branch 2.

[0028] Furthermore, the bottom branch 1 is connected to the inner wall of the straight conical section of the tailpipe 3, and the Y-shaped airfoil baffle is close to the upper end face of the tailpipe 3. This position precisely corresponds to the core area where the vortex belt is generated, and can directly act on the vortex and the vortex belt, solving the problem of limited intervention effect in non-core areas of the existing technology.

[0029] The width D1 of the bottom branch 1 along the radial direction of the tailrace pipe 3 satisfies: 0.45R≤D1≤0.55R; where R is the inlet radius of the tailrace pipe 3. That is, the width of the bottom branch 1 is approximately half the inlet radius of the tailrace pipe 3.

[0030] Within the cross section perpendicular to the tailpipe 3, the ratio of the width D2 of the cantilever branch 2 to the width D1 of the bottom branch 1 satisfies: 0.5≤D2 / D1≤1.

[0031] The length L1 of the bottom branch 1 along the axial direction of the tailwater pipe 3 satisfies: L1 < L0; where L0 is the length of the straight conical section of the tailwater pipe 3.

[0032] The end faces of the bottom branch 1 and the hanging branch 2 are perpendicular to the axis of the tailwater pipe 3.

[0033] The aforementioned size constraints ensure that the Y-shaped airfoil baffle is compatible with the tailrace tube 3 structure without generating additional hydraulic losses, while also guaranteeing the vortex suppression effect.

[0034] Furthermore, the inner wall of the straight conical section of the tailrace pipe 3 is provided with a groove, and one side of the bottom branch 1 is detachably connected to the groove. The Y-shaped airfoil baffle is detachably installed through the groove pre-set on the inner wall of the straight conical section of the tailrace pipe 3. The installation / removal state can be freely switched according to whether the turbine has entered the vortex zone, so as to meet the operating requirements under different working conditions and improve the equipment adaptability.

[0035] The method of using the Y-shaped airfoil baffle for suppressing power fluctuations in the vortex zone in this embodiment includes the following steps: S1: Determine the environment for starting and operating the turbine runner; if the startup process will enter the vortex zone, proceed to step S2; otherwise, proceed to step S3. S2: When starting and entering the vortex zone, install the Y-shaped airfoil baffle inside the tailrace pipe 3, start the turbine runner, the bottom branch 1 collides with the swirling flow to generate a reverse jet, and the suspended branch 2 destroys the vortex zone rotation structure. S3: When starting without entering the vortex zone, remove the Y-shaped airfoil baffle from the draft tube 3, and then start the turbine runner.

[0036] This invention only adds components inside the tailrace pipe 3, without affecting the rest of the structure. Furthermore, the Y-shaped airfoil baffle can be designed after the entire runner design is completed. During manufacturing, only the corresponding slot for the Y-shaped airfoil baffle needs to be added inside the tailrace pipe 3, and the Y-shaped airfoil baffle itself needs to be manufactured. Different Y-shaped airfoil baffles can also be added depending on the specific operating conditions.

[0037] Working Principle: In existing technologies, when a turbine starts up and enters the vortex zone, the water flow entering the draft tube 3 carries a certain circumferential velocity, easily forming a draft vortex. This vortex propagates downstream and simultaneously causes severe power oscillations in the turbine. However, in the Y-shaped airfoil baffle provided in this embodiment, which suppresses power fluctuations in the vortex zone, the Y-shaped airfoil baffle installed on the straight conical section of the draft tube 3 begins to function when the turbine enters the vortex zone. The bottom branch 1 connects to the inner wall of the draft tube 3, directly disrupting the rotational structure of the vortex. Simultaneously, two suspended branches 2 cut into the core rotational region of the vortex, their upstream surfaces colliding with the swirling flow, generating a backflow that neutralizes the swirling flow in the middle of the draft tube 3, effectively reducing the circumferential water velocity. The synergistic effect of these two aspects significantly reduces the intensity and scale of the vortex in the draft tube 3, thereby alleviating low-frequency power oscillations.

[0038] The Y-shaped airfoil baffle adopts an integrated design of "1 bottom branch 1 + 2 suspended branches 2", and all three branches are hydrofoils. The curved branches bend away from the central axis of the two curved branches. This structure can simultaneously achieve the dual functions of "bottom branch 1 colliding with the vortex to generate a reverse jet to neutralize the vortex" and "suspended branches 2 cutting into the core of the vortex belt to destroy the rotating structure". It is the core technical feature for suppressing the vortex belt and power fluctuation of the tailpipe 3.

[0039] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A Y-shaped airfoil baffle having a vortex sheet region with suppressed power fluctuations, characterized by: The bottom branch (1) is connected to the inner wall of the draft tube (3) on one side, and the other side is fixed with two branches of the suspended branch (2), and the included angle between the bottom branch (1) and the suspended branch (2) is greater than 120°.

2. A Y-shaped airfoil baffle with suppression of power fluctuations in the vortex zone according to claim 1, characterized in that: The cross section of the suspended branch (2) is arc-shaped, and the suspended branch (2) and the bottom branch (1) are smoothly connected.

3. A Y-shaped airfoil baffle with suppressed power fluctuations in the vortex sheet region according to claim 2, characterized in that: The suspended branch (2) is curved in the direction away from the other suspended branch (2).

4. The Y-shaped airfoil baffle with suppressed power fluctuation in vortex zone according to claim 1, characterized in that: The bottom branch (1) is connected to the inner wall of the straight cone section of the draft tube (3).

5. The Y-shaped airfoil baffle with suppressed power fluctuations in the vortex sheet region according to claim 1, wherein: The width D1 of the bottom branch (1) along the radial direction of the draft tube (3) satisfies: 0.45R≤D1≤0.55R; wherein R is the inlet radius of the draft tube (3).

6. A Y-shaped airfoil baffle having a suppression of power fluctuations in the vortex sheet region according to claim 5, characterized in that: In the cross section perpendicular to the draft tube (3), the ratio of the width D2 of the suspended branch (2) to the width D1 of the bottom branch (1) satisfies: 0.5≤D2 / D1≤1.

7. The Y-shaped airfoil baffle with suppressed power fluctuations in the vortex sheet region according to claim 1, wherein: The length L1 of the bottom branch (1) along the axial direction of the draft tube (3) satisfies: L1<L0; wherein L0 is the length of the straight cone section of the draft tube (3).

8. A Y-shaped airfoil baffle having a suppression of power fluctuations in the vortex sheet region according to claim 7, characterized in that: The end surface of the bottom branch (1) and the suspended branch (2) is perpendicular to the axis of the draft tube (3).

9. The Y-shaped airfoil baffle with suppressed power fluctuations in the vortex sheet region according to claim 1, wherein: The inner wall of the straight cone section of the draft tube (3) is provided with a clamping groove, and one side of the bottom branch (1) is detachably connected with the clamping groove.

10. A method of using a Y-type airfoil baffle having a power fluctuation suppressing vortex zone, using the Y-type airfoil baffle having a power fluctuation suppressing vortex zone according to any one of claims 1 to 9, characterized by: The method comprises the following steps: S1: judge the environment of the runner start operation; if the start process enters the vortex zone, step S2 is executed; otherwise, step S3 is executed; S2: under the condition of starting into the vortex zone, install the Y-shaped airfoil baffle in the draft tube (3), start the water turbine runner, the bottom branch (1) collides with the rotating flow to generate reverse jet, and the suspended branch (2) destroys the vortex rotating structure; S3: under the condition of starting without entering the vortex zone, remove the Y-shaped airfoil baffle from the draft tube (3), and then start the water turbine runner.

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