A device for eliminating cluster pressure pulsations in the lower cavity of the top cover of a pump-turbine

Abstract

The present invention discloses a device for eliminating clustered pressure pulsations in the lower cavity of the top cover of a pump-turbine, belonging to the technical field of water turbines. The device includes disturbance components arranged on the top cover or the bottom ring in the vaneless area of the pump-turbine. The vaneless area is the area formed between the head of the runner blade of the pump-turbine and the blade of the movable guide vane. The disturbance components are arranged in a circumferential circle around the runner of the water turbine on the top cover or the bottom ring, forming a continuous or discontinuous annular raised structure. By pasting the disturbance components on the top cover and / or the bottom ring in the vaneless area of the pump-turbine, the structure of the stationary components is changed, and the flow separation is destroyed, so as to achieve the effect of eliminating the clustered pressure pulsations in the lower cavity of the top cover and reducing the vibration of the top cover of the pump-turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic turbines, and particularly to a device for eliminating clustered pressure pulsations in the lower cavity of the top cover of a pump-turbine. Background Art

[0002] Currently, in the pump condition of a pump-turbine, especially in the high-lift condition, clustered pressure pulsations exist in the lower cavity of the top cover, as Figure 6 shown. These clustered pressure pulsations are characterized by small amplitude, wide frequency band, and large energy, and as the lift increases, the amplitude increases and the frequency shifts towards the high-frequency direction. In the high-lift pump condition of the pump-turbine, this pressure pulsation is likely to cause the vibration of the top cover of the pump-turbine.

[0003] In order to eliminate this pressure pulsation, researchers have conducted a series of model test research work on the lower cavity of the top cover of the pump-turbine, but none of them have achieved the desired effect. On the other hand, through numerical simulation, it is found that the clustered pressure pulsations in the lower cavity of the top cover are caused by rotational separation flow, that is, when the runner rotates, the outlet flow velocity distribution is uneven, flow separation occurs, and vortices are generated. To eliminate the clustered pressure pulsations, it is necessary to destroy the vortices.

[0004] In the prior art, the Chinese invention patent with the publication number CN115711243A discloses a movable guide vane with a horizontal edge that can eliminate the separated-flow vortices in the vane-less area of a pump-turbine. This patent solution sets a horizontal edge on the side of the movable guide vane close to the runner to eliminate the separated-flow vortices, thereby suppressing the problem of excessive vibration displacement of the top cover of the pump-turbine caused by the separated-flow vortices in the vane-less area under the high-lift pump condition. However, through experimental verification, it is found that the horizontal edge structure in this patent does not achieve the effect of eliminating the separated-flow vortices. Analyzing the reason, it is because the movable guide vane is far from the runner, and considering that the design of the horizontal edge cannot affect the normal opening and closing of the movable guide vane, the designed length of the horizontal edge is limited, resulting in its inability to achieve the expected effect of eliminating the separated-flow vortices. Summary of the Invention

[0005] In order to solve the problem that the clustered pressure pulsations in the lower cavity of the top cover of the existing pump-turbine cause the vibration of the top cover of the pump-turbine, the present invention proposes a device for eliminating the clustered pressure pulsations in the lower cavity of the top cover of the pump-turbine. By setting annular disturbance components on the top cover and / or bottom ring in the vane-less area, the structure of the stationary components is changed, thereby destroying the separated-flow vortex structure and achieving the effect of eliminating the clustered pressure pulsations in the lower cavity of the top cover.

[0006] To achieve the above invention purpose, the technical solution of the present invention is as follows:

[0007] A device for eliminating clustered pressure pulsations in the lower chamber of a top cover of a water pump turbine comprises a disturbance component arranged on a top cover or a bottom ring in a bladeless area of the water pump turbine, wherein the bladeless area is an area formed between the heads of runner blades and movable guide vanes of the water pump turbine; the disturbance component is arranged on the top cover or the bottom ring around the circumference of the water turbine runner to form a continuous or discontinuous annular convex structure.

[0008] Furthermore, the disturbance component is provided simultaneously on the top cover and the bottom ring of the bladeless area.

[0009] Furthermore, the cross-section of the disturbance component along the axial direction of the impeller is distributed from the impeller side to the movable guide vane side, and the length of the cross-section satisfies that the end thereof close to the impeller does not exceed the edge of the fixed portion thereof close to the impeller side, and the end thereof close to the movable guide vane does not exceed the circle formed by the positions of the low-pressure edges of the guide vanes when the movable guide vane rotates clockwise around the guide vane shaft from a closed state to reach a maximum opening.

[0010] Furthermore, a starting end of the section of the disturbance component along the axial direction of the rotor close to the rotor coincides with an edge of the fixed portion of the disturbance component close to the rotor.

[0011] Furthermore, the cross-sectional shape of the disturbance component along the axial direction of the runner is a NACA airfoil, a circle, a rectangle, a trapezoid or a triangle.

[0012] Furthermore, the thickness of the disturbance component satisfies that the influence of the disturbance component on the hydraulic performance of the turbine is less than 1%.

[0013] Furthermore, the disturbance component is fixed by gluing, and the adhesive is TS828 high-performance acrylic structural adhesive.

[0014] Furthermore, for the disturbance component arranged on the top cover, the cross section thereof along the axial direction of the runner is flush with the side edge of the top cover at one end close to the runner.

[0015] Furthermore, for the disturbance component arranged on the bottom ring, the end of the cross section thereof along the axial direction of the runner close to the runner is flush with the side edge of the bottom ring.

[0016] Further, when the cross-sectional shape of the disturbance component along the axial direction of the runner is a NACA airfoil, its shape parameters are determined in the following manner:

[0017] First calculate the coordinates of the middle camber line of the airfoil y c :

[0018] ;

[0019] Then calculate the thickness distribution of the airfoil y t :

[0020] ;

[0021] In the formula, m represents the maximum camber of the airfoil, p represents the position of the maximum camber of the airfoil, t represents the maximum thickness of the airfoil, c represents the chord length, and x is the abscissa;

[0022] Then calculate the specific values of the upper and lower sides of the airfoil:

[0023] ;

[0024] In summary, the slope of the middle arc is calculated θ :

[0025] ;

[0026] wherein, upper represents the upper side of the airfoil, and lower represents the lower side of the airfoil, θ is the slope of the middle arc.

[0027] In summary, the present invention has the following advantages:

[0028] 1. By pasting disturbance components on the top cover and / or bottom ring in the vaneless area of the pump-turbine, the structure of the stationary components is changed, thereby destroying the flow separation, achieving the effect of eliminating the clustered pressure pulsation in the lower cavity of the top cover and reducing the vibration of the top cover of the pump-turbine;

[0029] 2. In the present invention, the installation positions of the disturbance components are exactly in the two main active directions of the vortex, and the separated vortex structures in these two directions can be correspondingly destroyed. By respectively installing disturbance components on the top cover or bottom ring in the vaneless area of the turbine, about 80% of the clustered pressure pulsation can be eliminated; by simultaneously installing disturbance components on the top cover and bottom ring in the vaneless area, the clustered pressure pulsation can be basically eliminated;

[0030] 3. In the present invention, the installation positions of the disturbance components are closer to the runner side, and their structural design can ensure the elimination of the separated vortex structure while minimizing the impact on the hydraulic performance of the turbine. Description of the Drawings

[0031] Figure 1 is the top view of the structure of the pump-turbine;

[0032] Figure 2 is the schematic diagram of the maximum opening of the movable guide vane;

[0033] Figure 3 is the schematic diagram of the installation position of the disturbance component (axial sectional view of the pump-turbine);

[0034] Figure 4Schematic cross-sectional view of the disturbing component provided on the top cover along the axial direction of the runner, and also Figure 3 Enlarged schematic view at box A in the Chinese figure;

[0035] Figure 5 Structural section where the cross-sectional shape of the disturbing component is a NACA airfoil;

[0036] Figure 6 Model test results of the pressure pulsation in the lower cavity of the top cover before the disturbing component is set;

[0037] Figure 7 Model test results of the pressure pulsation in the lower cavity of the top cover after the disturbing component is set;

[0038] In the figure:

[0039] 1. Spiral case; 2. Stay vane; 3. Guide vane; 4. Runner; 6. Low-pressure side circle at the maximum opening of the guide vane; 7. Side of the top cover, 8. Guide vane rotating shaft; 9. Lower cavity of the top cover; 10. Pressure sensor; 11. Clearance; 12. Vaneless space; 13. Head; 14. Top cover; 15. Crown; 16. Runner blade; 17. Lower ring; 18. Bottom ring; 19. Disturbing component. Specific implementation manners

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0042] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0044] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Embodiment 1

[0046] In order to eliminate the clustered pressure pulsations in the lower cavity of the top cover under high head conditions of a pump-turbine, the present invention provides a device for eliminating the clustered pressure pulsations in the lower cavity of the top cover of a pump-turbine.

[0047] Referring to Figure 1 the structural top view of the pump-turbine shown in the figure, it includes five main flow components: a spiral case 1, fixed guide vanes 2, movable guide vanes 3, a runner 4, and a draft tube (not shown in the figure). When the movable guide vanes 3 rotate clockwise around the guide vane rotating shaft 8 from the closed state to the maximum opening, the positions where the low-pressure edges of the guide vanes are located form the circle of the low-pressure edges at the maximum opening of the movable guide vanes 6, as Figure 2 shown in the figure.

[0048] As Figure 3 shown in the axial sectional view of the pump-turbine, the rotating component of the pump-turbine is the runner 4, and the runner 4 includes a crown 15, runner blades 16, and a lower ring 17. There are gaps 11 and a lower cavity 9 between the crown 15 of the runner 4 and the top cover 14. The lower cavity 9 is the cavity formed between the bottom surface of the top cover 14 and the top surface of the runner 4, and the gap 11 is the gap formed between the side surface of the runner 4 and the side surface of the top cover 14. A pressure sensor 10 is installed on the top cover 14 to measure the pressure pulsations in the lower cavity of the top cover.

[0049] The movable guide vanes 3 are located between the top cover 14 and the bottom ring 18, and the area between the head 13 (i.e., the end far from the center of the runner 4) of the runner blade 16 and the blades of the movable guide vanes 3 forms a non-blade area 12.

[0050] Before designing this device, it was found through numerical simulation that the clustered pressure pulsation in the lower cavity of the top cover is caused by rotational separation flow. On the one hand, the vortices rotate with the runner, generating clustered pressure pulsations, which are transmitted into the lower cavity of the top cover through the gap 11 between the runner and the top cover; on the other hand, the vortices move towards the direction of the movable guide vane 3. The closer the elimination measure is to the runner outlet, the more obvious the effect; the farther away from the runner outlet, the worse the effect, and even there is no effect.

[0051] Therefore, as Figure 3 shown, a device for eliminating the clustered pressure pulsation in the lower cavity of the top cover of a pump-turbine proposed by the present invention reduces the clustered pressure pulsation in the lower cavity of the top cover by arranging a disturbance component 19 on the top cover 14 or the bottom ring 18 in the vaneless space 12. The disturbance component 19 is a raised structure that protrudes from the surface of its fixed part, and it is arranged in a circumferential circle around the runner 4 to form a continuous or discontinuous annular raised structure.

[0052] By arranging the disturbance component 19 on the top cover 14 or the bottom ring 18 in the vaneless space 12, the present invention changes the structure of the stationary component, thereby destroying the flow separation and being able to eliminate about 80% of the clustered pressure pulsation.

[0053] Embodiment 2

[0054] Based on Embodiment 1, this embodiment proposes a device for eliminating the clustered pressure pulsation in the lower cavity of the top cover of a pump-turbine. The difference from Embodiment 1 is that:

[0055] In this embodiment, disturbance components are arranged on both the top cover 14 and the bottom ring 18 in the vaneless space 12. The positions of the disturbance components 19 on the top cover 14 or the bottom ring 18 in the vaneless space 12 are exactly in the two main moving directions of the vortices, so as to destroy the separated vortex structures in these two directions and achieve the effect of basically eliminating the clustered pressure pulsation in the lower cavity of the top cover.

[0056] Embodiment 3

[0057] Based on Embodiment 1 or Embodiment 2, this embodiment further describes the specific structure of the disturbance component.

[0058] Preferably, in this embodiment, the cross-sectional shape of the disturbance component 19 along the axial direction of the runner 4 can be in the shape of a NACA airfoil, a circle, a rectangle, a trapezoid, a triangle, etc. The effects of the foregoing various shapes are quite equivalent, and when arranged on both the top cover 14 and the bottom ring 18, the clustered pressure pulsation can be basically eliminated.

[0059] In this solution, the disturbing component 19 is distributed along the axial cutting section of the runner 4 from the side of the runner to the side of the movable guide vane. The length l of this cutting section satisfies that one end close to the runner 4 does not exceed the edge of its corresponding fixed part (i.e., the top cover 14 or the bottom ring 18) on the side close to the runner, and one end close to the movable guide vane does not exceed the circle formed by the positions of the low-pressure edges of each guide vane when the movable guide vane 3 rotates clockwise around the guide vane rotating shaft 8 from the closed state to the maximum opening degree, that is, as shown in Figure 2 the low-pressure edge circle 6 of the maximum opening degree of the movable guide vane shown.

[0060] Preferably, in order to improve the disturbing effect, in this solution, for the disturbing component 19 provided on the top cover 14, one end of its axial cutting section along the runner 4 close to the runner is flush with the side edge 7 of the top cover, as shown in Figure 4 shown. For the disturbing component 19 provided on the bottom ring 18, one end of its axial cutting section along the runner 4 close to the runner is flush with the side edge of the bottom ring, as shown in Figure 3 shown.

[0061] In this embodiment, the disturbing component 19 can be made of metal, plastic, alloy steel, etc., or can be directly formed by using P551 - 1052 type alloy putty. The disturbing component 19 is fixed by an adhesive, and the adhesive can use the existing TS828 high-performance acrylic structural adhesive, which has good adhesive properties and has been verified to be able to achieve reliable fixation.

[0062] The thickness design of the disturbing component 19 should consider its influence on the hydraulic performance of the pump-turbine. Generally speaking, the thickness h of the disturbing component 19 should satisfy that the influence on the hydraulic performance is less than 1%, which can be determined by model tests.

[0063] The NACA airfoil is a series of standard airfoils developed by the National Advisory Committee for Aeronautics (NACA, now NASA) and is widely used in the fields of aviation and fluid mechanics. As shown in Figure 5 the NACA airfoil structure. In the figure, x is the abscissa, y is the ordinate, m represents the maximum camber, p represents the position of the maximum camber, t represents the maximum thickness, and c is the chord length (i.e., the maximum value of x), which is determined by the digital coding of the standard airfoil. For example, for NACA1315, the code "1315" means that m is 1% of the chord length c, p is 30% of the chord length c, and t is 15% of the chord length c.

[0064] In this embodiment, the shape of this airfoil structure is determined according to the following formula.

[0065] First, calculate the coordinates of the middle arc L1 of the airfoil y c :

[0066] ;

[0067] Calculate the thickness distribution again y t :

[0068] ;

[0069] Calculate the specific values of the upper and lower sides of the airfoil again:

[0070] ;

[0071] In summary, the slope of the middle arc is calculated θ :

[0072] ;

[0073] Among them, upper represents the upper side and lower represents the lower side, θ is the slope of the middle arc L1, and arctan() is the operator for finding the arcsine of a trigonometric function, d y c / d x is the derivative of the middle arc.

[0074] The verification process of the present invention is described below:

[0075] Install the spiral case 1 and the stay vanes 2 according to the requirements of the model test;

[0076] Process the disturbance component 19, and then paste the disturbance component 19 on the top cover 14 and the bottom ring 18 of the movable vane 3;

[0077] After the glue dries, install it on the model test device, then install the runner 4, and finally install the draft tube;

[0078] Conduct the model test of the pump-turbine in pump mode according to the model test specifications, and record the test results;

[0079] Perform Fourier analysis on the pressure pulsation data in the lower cavity of the top cover in the test results to obtain the frequency characteristics of the pressure pulsation.

[0080] After pasting the disturbance component, the model test results of the pressure pulsation in the lower cavity of the top cover are as Figure 7 shown, and the clustered pressure pulsation basically disappears, indicating that the present solution can achieve the expected effect.

[0081] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A device for eliminating clustered pressure pulsations in the lower cavity of the top cover of a pump-turbine, characterized in that, Comprising a disturbance component (19) provided on the top cover (14) or the bottom ring (18) in the vaneless area (12) of a pump-turbine, wherein the vaneless area (12) is the area formed between the head (13) of the runner blades (16) of the pump-turbine and the guide vane blades; the disturbance component (19) is arranged in a circumferential circle around the turbine runner (4) on the top cover (14) or the bottom ring (18) to form a continuous or discontinuous annular convex structure; the cross-sectional shape of the disturbance component (19) along the axial direction of the runner (4) is a NACA airfoil, a circle, a rectangle, a trapezoid or a triangle, and the thickness of the disturbance component (19) satisfies that the influence on the hydraulic performance of the turbine is less than 1%.

2. The device for eliminating the clustered pressure pulsation in the lower cavity of the top cover of a pump-turbine according to claim 1, characterized in that, The disturbance component (19) is provided on both the top cover (14) and the bottom ring (18) in the vaneless area (12).

3. A device for eliminating the cluster pressure pulsation in the lower cavity of the top cover of a pump-turbine, as described in claim 1 or 2, characterized in that, The cross-sectional cut along the axial direction of the runner (4) of the disturbance component (19) is distributed from the side of the runner (4) to the side of the movable guide vane (3). The length of this cross-sectional cut satisfies that one end close to the runner (4) does not exceed the edge of the fixed part where it is located on the side close to the runner (4), and one end close to the movable guide vane (3) does not exceed the circle formed by the positions of the low-pressure edges of each guide vane when the movable guide vane (3) rotates clockwise around the guide vane rotating shaft (8) from the closed state to reach the maximum opening degree.

4. The device for eliminating the cluster pressure pulsation in the lower cavity of the top cover of a pump-turbine according to claim 3, characterized in that, For the disturbance component (19) provided on the bottom ring (18), one end of the cross-sectional cut along the axial direction of the runner (4) close to the runner (4) is flush with the side edge of the bottom ring (18).

5. A device for eliminating the clustered pressure pulsation in the lower cavity of the top cover of a pump-turbine, characterized in that, For the disturbance component (19) provided on the top cover (14), one end of the cross-sectional cut along the axial direction of the runner (4) close to the runner (4) is flush with the side edge of the top cover (14).

6. The device for eliminating the cluster pressure pulsation in the lower cavity of the top cover of a pump-turbine according to claim 1, characterized in that, The disturbance component (19) is fixed by means of pasting, and the adhesive is TS828 high-performance acrylic structural adhesive.

7. The device for eliminating the cluster pressure pulsation in the lower cavity of the top cover of a pump-turbine according to claim 3, characterized in that, When the cross-sectional shape of the disturbance component (19) along the axial direction of the runner is a NACA airfoil, its shape parameters are determined in the following manner: First, calculate the coordinates of the mean camber line of the airfoil y c : ； Calculate the thickness distribution of the airfoil again y t : ； In the formula, m represents the maximum camber, p represents the position of the maximum camber, t represents the maximum thickness, c represents the chord length, and x represents the abscissa; Then calculate the specific values of the upper and lower edges of the airfoil: ; In summary, the slope of the intermediate arc is calculated θ : ； where upper represents the upper edge of the airfoil and lower represents the lower edge of the airfoil, θ is the slope of the middle arc.

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