Three-chamber water chamber type surge chamber structure and hydraulic design method thereof

Abstract

The invention discloses a three-cavity water chamber type surge chamber structure and a hydraulic design method thereof, and belongs to the technical field of water conservancy and hydropower facilities. A three-cavity water chamber type surge chamber structure comprises a vertical shaft, the side wall of the upper end of the vertical shaft is connected with a cavity structure, the cavity structure comprises an upper cavity, a middle cavity and a lower cavity, and the upper cavity, the middle cavity and the lower cavity are sequentially and perpendicularly connected to one side of the side wall of the vertical shaft. The upper cavity, the middle cavity and the lower cavity are each of a gradual change structure, and the lower end of the vertical shaft is connected with a communicating pipe used for being connected with a diversion tunnel. By arranging the upper cavity, the middle cavity and the lower cavity, the maximum surge amplitude can be effectively stabilized, convergence of water level fluctuation is accelerated, meanwhile, good hydraulic characteristics and structural characteristics are achieved, stable operation of a water diversion system is ensured, and the design requirement of a surge chamber can be met especially in a long-distance, large-flow and high-water-head water diversion system.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy and hydropower facilities, and in particular relates to a three-chamber water chamber type surge chamber structure and a hydraulic design method thereof. Background Art

[0002] In the process of achieving the "dual carbon" goal, new energy represented by solar energy and wind energy will become an inevitable trend of future development. However, due to the randomness and fluctuation of solar energy and wind energy, the development and utilization of water resources will play an important role in the future new energy field.

[0003] Water diversion and regulation projects, hydropower stations, pumped-storage power stations and other fields all involve water diversion systems. Affected by unstable factors or transient characteristics, the water diversion system pipelines will experience varying degrees of pressure and flow changes, resulting in the propagation of water hammer waves and leading to unstable operation of the system. The surge tank is an important equalizing structure in the water diversion system of hydropower projects. Its reasonable shape selection and size design are crucial to the stable operation of the water diversion system.

[0004] In view of the characteristics of different water diversion systems, some different forms of surge chambers have been designed and developed in engineering. Patent CN104110016A discloses a new type of piston energy dissipation surge chamber, which has the characteristics of a simple surge chamber and an impedance surge chamber; Patent CN110219288A proposes a double impedance surge chamber, in which two connecting pipes are provided between the pressure pipe and the surge chamber to achieve local energy loss; Patent CN118224543A proposes a combined air cushion surge chamber, which includes an inclined shaft extension pipe and an air cushion surge chamber, etc., which can reduce the volume of the air cushion surge chamber; Patent CN201473934U involves a diversion pier type differential surge chamber, which can improve the pressure regulation The force distribution at the bottom plate of the chamber; Patent CN201738288U proposes a symmetrically arranged double-chamber surge chamber structure, in which the lower chamber and the upper chamber are symmetrically distributed on both sides of the shaft; Patent CN117230762A sets two chambers at the same horizontal height, and connects the two chambers to the main pipe respectively through a connecting pipe to form a new double-chamber surge chamber. The optimization design method of the above-mentioned surge chamber is suitable for water diversion systems with medium and low heads. However, with the development of long-distance, large-flow, and ultra-high-head water diversion systems, the design and optimization methods of existing surge chambers have gradually failed to meet the needs of actual projects. Therefore, it is urgent to propose a three-chamber water chamber surge chamber structure and its hydraulic design method. Summary of the invention

[0005] The purpose of the present invention is to provide a three-chamber water chamber type pressure regulating chamber structure and a hydraulic design method thereof in view of the problems existing in the prior art.

[0006] To achieve the above-mentioned purpose, the invention adopts the following technical scheme: a three-chamber water chamber type pressure regulating chamber structure, including a vertical shaft, the side wall of the upper end of the vertical shaft is connected with a chamber structure, the chamber structure includes an upper chamber, a middle chamber and a lower chamber, the upper chamber, the middle chamber and the lower chamber are vertically connected in sequence on one side of the side wall of the vertical shaft, the upper chamber, the middle chamber and the lower chamber are respectively gradual structures, and the size of the inlet end of the upper chamber, the middle chamber and the lower chamber is larger than the size of the tail end, and the lower end of the vertical shaft is connected with a connecting pipe for connecting to a water diversion tunnel.

[0007] By adopting the above technical scheme, the water hammer pressure of the water diversion system is regulated through the connection between the vertical shaft and the upper chamber, the middle chamber and the lower chamber, and the water level fluctuation in the pressure regulating chamber is effectively suppressed. The design of the gradient structure can effectively exhaust the air during the chamber flooding process, and the flow is smoother, thereby reducing the energy loss in the unstable gas-liquid two-phase flow process.

[0008] Optionally, the cross-sections of the upper chamber, the middle chamber and the lower chamber are respectively door-hole-shaped, the upper parts of the cross-sections of the upper chamber, the middle chamber and the lower chamber are respectively semicircular structures, and the lower parts are rectangular structures, the areas of the rectangular structures of the upper chamber, the middle chamber and the lower chamber decrease successively from the inlet end, and the radius of the semicircular structures of the upper chamber, the middle chamber and the lower chamber from the inlet end to the tail end remains unchanged.

[0009] By adopting the above technical solution, a door-shaped cross-section design is formed, in which the upper part is a semicircular structure and the lower part is a rectangular structure. The area of ​​the rectangular structure decreases from the inlet end to the tail end, while the radius of the semicircular structure remains unchanged. This design makes the chamber more in line with the principles of fluid mechanics, which is beneficial to the stable flow of the fluid and the overall stability and deformation resistance of the structure.

[0010] Optionally, the cross-sectional area of ​​the shaft is calculated according to Thomas' critical cross-sectional area formula, then the cross-sectional area of ​​the shaft is Satisfies the following relationship: , where K is the coefficient, and ; is the critical cross-sectional area of ​​Thomas.

[0011] By adopting the above technical solution, the cross-sectional area of ​​the shaft is calculated according to the Thomas critical cross-sectional area formula, which ensures the rationality of the shaft hydraulic design. This step is the basis of the design and is crucial for subsequent design work.

[0012] Optionally, the cross-sectional area of ​​the diversion tunnel is , then the cross-sectional area of ​​the connecting pipe is , satisfying the following relationship: , and the cross-sectional area of ​​the connecting pipe The cross-sectional area of ​​the shaft Satisfies the following relationship, < .

[0013] By adopting the above technical solution, the cross-sectional area of ​​the connecting pipe is calculated according to the cross-sectional area of ​​the water diversion tunnel, ensuring that the connecting pipe can effectively suppress large water level fluctuations and accelerate the convergence speed of the fluctuations.

[0014] Optionally, the lengths of the rectangular structures at the inlet ends of the upper chamber, the middle chamber and the lower chamber are respectively a and b, and the radii of the semicircular structures of the upper chamber, the middle chamber and the lower chamber are respectively The lengths of the upper chamber, the middle chamber and the lower chamber are L respectively, and the slopes of the top plate and the bottom plate of the upper chamber, the middle chamber and the lower chamber are and , and 0< <2% and <2%, then the height of the rectangular structure of the upper chamber, the middle chamber and the tail end of the lower chamber is , respectively satisfying the following relations: .

[0015] By adopting the above technical solution, the design of the chamber size takes into account multiple factors such as the area of ​​the rectangular structure, the radius of the semicircular structure, the chamber length, and the slope of the top plate and the bottom plate. These design parameters jointly determine the hydraulic properties of the chamber, ensuring that the water flow can maintain a stable flow state when passing through each chamber.

[0016] Optionally, the length of the connecting pipe is , the elevation of the bottom of the connecting pipe is , the water level of the reservoir is The height from the bottom plate of the upper chamber inlet to the upper surface of the water diversion tunnel is The height from the horizontal plane in the upper chamber to the bottom plate of the upper chamber is the submerged depth of the upper chamber. , then the upper chamber submergence depth Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the upper chamber, and R is the radius of the semicircular structure at the inlet end of the upper chamber.

[0017] By adopting the above technical solution, it can be ensured that the upper chamber plays the best regulating role in the pressure regulating chamber structure while maintaining the stability and reliability of the structure. By reasonably designing the depth, it can be ensured that the upper chamber can maintain a stable operating state while avoiding the adverse effects of excessively high or low water levels on the structure.

[0018] Optionally, the head loss of all the units in steady-state operation at rated conditions is The height from the bottom plate of the lower chamber inlet to the upper surface of the water diversion tunnel is The height from the horizontal plane in the lower chamber to the bottom plate of the lower chamber is the submerged depth of the lower chamber. , then the submerged depth of the lower chamber is Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the lower chamber, and R is the radius of the semicircular structure at the inlet end of the lower chamber.

[0019] By adopting the above technical solution, the position of the lower chamber is reasonably set to ensure that the lower chamber can play the best regulating role during the pressure regulation process while maintaining the stability and reliability of the structure.

[0020] Optionally, the vertical height between the top plate of the middle chamber and the bottom plate of the upper chamber is , the vertical height between the bottom plate of the middle chamber and the top plate of the lower chamber is ,but .

[0021] By adopting the above technical solution, the middle chamber is located between the upper chamber and the lower chamber, and stores excess water when the load is dropped. When the load is increased, it assists the lower chamber to replenish more water, thereby achieving the purpose of improving the water hammer pressure of the water diversion system and reducing the water level fluctuation in the pressure regulating chamber.

[0022] Optionally, after the pressure-surge chamber structure design is completed, the hydraulic characteristics of the pressure-surge chamber structure are verified by a one-dimensional numerical calculation method.

[0023] By adopting the above technical solution and verifying the hydraulic characteristics of the surge chamber structure through one-dimensional numerical calculation, problems in the design can be discovered and corrected in a timely manner to ensure that the performance of the structure meets the requirements. This step is an important part of the design process and is crucial to ensuring the accuracy and reliability of the final design.

[0024] Optionally, a hydraulic design method for a three-chamber water chamber type surge chamber structure comprises the following steps:

[0025] Determine the cross-sectional area F of the shaft;

[0026] Calculating the size of the connecting pipe;

[0027] Designing the sizes of the upper chamber, the middle chamber, and the lower chamber;

[0028] determining positions of the upper chamber, the middle chamber, and the lower chamber;

[0029] A new pressure regulating chamber structure is designed based on the cross-sectional area of ​​the shaft, the shape of the connecting pipe, the sizes of the upper chamber, the middle chamber and the lower chamber, and the positions of the upper chamber, the middle chamber and the lower chamber, and the hydraulic characteristics of the new pressure regulating chamber structure are verified.

[0030] By adopting the above technical solution, through a series of steps, the rationality and reliability of the surge chamber structure are ensured. Each step has been calculated and considered to ensure the accuracy and practicality of the final design.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. In the water diversion system with long distance, large flow and high head, the present invention makes full use of the horizontal space by adding an upper chamber, a middle chamber and a lower chamber, so that under the same vertical height, the three-chamber water chamber type surge chamber structure has higher applicability and stability than the conventional impedance surge chamber and the simple surge chamber; this design can more effectively adjust the water hammer pressure and ensure the stable operation of the water diversion system.

[0033] 2. Compared with three single-body surge chambers, the present application arranges the upper chamber, the middle chamber and the lower chamber vertically in sequence, and directly connects them with the vertical shaft. Since the three-chamber water chamber surge chamber structure adds the middle chamber, the surge chamber structure can store excess water when the load is shed, which can effectively suppress the maximum surge amplitude and help accelerate the convergence of water level fluctuations; when the load is increased, the surge chamber structure can assist the lower chamber to replenish more water, thereby achieving the purpose of suppressing the water level fluctuations in the surge chamber structure and reducing the fluctuation period.

[0034] 3. The design of the gradient structure of the present invention can make the fluid flow in the chamber smoother, thereby reducing the energy loss in the unstable gas-liquid two-phase flow process. At the same time, the doorway-shaped design can effectively disperse and withstand the pressure from the rock mass. Compared with the square chamber, its structure is more stable, and the doorway-shaped design can be applied to a variety of geological conditions. The gradient structure is combined with the doorway-shaped design to optimize fluid flow, enhance structural stability, and improve the pressure regulation effect.

[0035] 4. The present invention reasonably designs the parameters such as the size, position and cross-sectional area of ​​each chamber, so that the pressure regulating chamber can better adapt to the changes in water flow under different working conditions, thereby improving the stability and reliability of the pressure regulating chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the surge chamber structure of the present invention;

[0037] Figure 2 This is a schematic diagram of the main structure of the surge chamber structure of the present invention;

[0038] Figure 3 For the present invention Figure 2 The enlarged structural diagram at A in the middle;

[0039] Figure 4 It is a schematic diagram of the partial structure of the pressure regulating chamber structure of the present invention;

[0040] Figure 5 This is a schematic diagram of the cross-sectional structure of the inlet end of the chamber structure of the present invention;

[0041] Figure 6 A schematic diagram comparing the hydraulic characteristics of load shedding and load increasing according to the present invention;

[0042] Figure 7 It is a schematic diagram comparing the hydraulic characteristics of the double-chamber type surge chamber and the three-chamber type surge chamber of the present invention.

[0043] In the figure: 1. Vertical shaft; 2. Chamber structure; 21. Upper chamber; 22. Middle chamber; 23. Lower chamber; 3. Connecting pipe; 4. Water diversion tunnel; 5. Pressure pipe. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as "middle", "upper", "lower", "left", "right", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings, and are 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0046] like Figure 1—5, the specific scheme of the embodiment is as follows: a three-chamber water chamber type surge chamber structure, including a vertical shaft 1, the vertical shaft 1 is used as the support and core part of the entire surge chamber structure, and is used to connect three horizontal chambers, the side wall of the upper end of the vertical shaft 1 is connected with a chamber structure 2, the chamber structure 2 includes an upper chamber 21, a middle chamber 22 and a lower chamber 23, the upper chamber 21, the middle chamber 22 and the lower chamber 23 are vertically connected to one side of the side wall of the vertical shaft 1 in sequence, the upper chamber 21, the middle chamber 22 and the lower chamber 23 are respectively gradual structures, and the size of the inlet end of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is larger than the size of the tail end;

[0047] The cross-sections of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are respectively door-shaped, and the upper parts of the cross-sections of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are respectively semicircular structures, and the lower parts are rectangular structures. The areas of the rectangular structures of the upper chamber 21, the middle chamber 22 and the lower chamber 23 from the inlet end to the tail end are reduced successively, and the radius of the semicircular structures of the upper chamber 21, the middle chamber 22 and the lower chamber 23 from the inlet end to the tail end remains unchanged. The design of the gradual structure ensures that the exhaust of each chamber is smooth during the rising water level and no harmful air masses are generated. The lower end of the vertical shaft 1 is connected to a connecting pipe 3 for connecting to the water diversion tunnel 4. The connecting pipe 3 is a key component connecting the vertical shaft 1 and the water diversion tunnel 4. The connecting pipe 3 is vertically connected to the surface of the water diversion tunnel 4, and the water diversion tunnel 4 is connected to a pressure pipe 5 at one end close to the connecting pipe 3.

[0048] A hydraulic design method for a three-chamber water chamber type surge chamber structure comprises the following steps:

[0049] Determine the cross-sectional area F of the shaft 1;

[0050] The cross-sectional area of ​​the shaft 1 is calculated according to Thomas' critical cross-sectional area formula. Then, the cross-sectional area of ​​the shaft 1 is Satisfies the following relationship: , where K is the coefficient, and ; is the critical cross-sectional area of ​​Thomas; by determining the shape of shaft 1, a reliable supporting foundation can be provided for the subsequent chamber design.

[0051] Calculate the size of the connecting pipe 3;

[0052] The cross-sectional area of ​​the diversion tunnel 4 is , then the cross-sectional area of ​​the connecting pipe 3 is , satisfying the following relationship: ; and the cross-sectional area of ​​the connecting pipe 3 The cross-sectional area of ​​the shaft 1 Satisfies the following relationship, < Through the reasonable design of the connecting pipe 3, the connecting pipe 3 can play the role of an impedance hole, effectively suppress the water level fluctuation in the pressure regulating chamber structure, and accelerate the convergence speed of the fluctuation, thereby ensuring the stable operation of the entire system.

[0053] Designing the sizes of the upper chamber 21, the middle chamber 22 and the lower chamber 23;

[0054] The lengths of the rectangular structures at the inlet ends of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are respectively a and b, and the cross-sectional radii of the semicircular structures of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are respectively The lengths of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are L respectively, and the slopes of the top plate and the bottom plate of the upper chamber 21, the middle chamber 22 and the lower chamber 23 are and , and 0< <2% and <2%, then the height of the rectangular structure of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is They satisfy the following relations respectively: The size design of the upper chamber 21, the middle chamber 22 and the lower chamber 23 takes into account the smooth discharge of gas during the rising water level, avoiding the formation of harmful air masses, and the body design of each chamber further takes into account the stability of the enhanced structure and the smoothness of the water flow.

[0055] Determine the positions of the upper chamber 21, the middle chamber 22 and the lower chamber 23;

[0056] The position of the upper chamber 21 is determined by the water level of the reservoir. After the unit is shut down, the water level in the pressure regulating chamber is flush with the water level of the reservoir, ensuring that the water level of the reservoir is slightly higher than the bottom plate height of the upper chamber 21. The length of the connecting pipe 3 is , the elevation of the bottom of the connecting pipe 3 is , the water level of the reservoir is The height from the bottom plate of the inlet end of the upper chamber 21 to the upper surface of the water diversion tunnel 4 is The height from the horizontal plane in the upper chamber 21 to the bottom plate of the upper chamber 21 is the submerged depth of the upper chamber 21. , then the submerged depth of the upper chamber 21 is Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the upper chamber 21, R is the radius of the semicircular structure at the inlet end of the upper chamber 21, and the height of the upper chamber 21 must ensure that the safety excess height above the highest surge water level is not less than 1m. The design of the upper chamber 21 can ensure that the upper chamber 21 plays the best regulating role in the surge chamber structure while maintaining the stability and reliability of the structure.

[0057] The position of the lower chamber 23 is determined by the water level of the reservoir and the head loss of all units in steady-state operation at rated conditions, ensuring that the water level in the lower chamber 23 is slightly higher than the bottom plate height of the lower chamber 23. Assuming that the head loss of all units in steady-state operation at rated conditions is The height from the bottom plate of the inlet end of the lower chamber 23 to the upper surface of the water diversion tunnel 4 is The height from the horizontal plane in the lower chamber 23 to the bottom plate of the lower chamber 23 is the submerged depth of the lower chamber 23. , then the submerged depth of the lower chamber 23 is Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the lower chamber 23, R is the radius of the semicircular structure at the inlet end of the lower chamber 23, the bottom of the lower chamber 23 should be lower than the lowest surge water level, and the position of the lower chamber 23 should be reasonably set to ensure that the lower chamber 23 can play the best regulating role in the pressure regulation process while maintaining the stability and reliability of the structure.

[0058] The middle chamber 22 is located between the upper chamber 21 and the lower chamber 23. The height between the top plate of the middle chamber 22 and the bottom plate of the upper chamber 21 is The height between the bottom plate of the middle chamber 22 and the top plate of the lower chamber 23 is ,but The middle chamber 22 is located between the upper chamber 21 and the lower chamber 23. It stores excess water when the load is dropped and assists the lower chamber 23 in replenishing more water when the load is increased, thereby achieving the purpose of improving the water hammer pressure of the water diversion system and reducing the water level fluctuation in the pressure regulating chamber.

[0059] The height of the shaft 1 is The top height of the shaft 1 should be at least 1m higher than the inlet top plate of the upper chamber 21, and the height of the connecting pipe 3 should be The total height of the surge chamber structure is .

[0060] A new surge chamber structure is designed based on the shape of the shaft 1, the shape of the connecting pipe 3, the sizes of the upper chamber 21, the middle chamber 22 and the lower chamber 23, and the positions of the upper chamber 21, the middle chamber 22 and the lower chamber 23, and the hydraulic characteristics of the new surge chamber structure are verified;

[0061] After the new surge chamber structure design is completed, the hydraulic characteristics of the new surge chamber structure are verified through one-dimensional numerical calculations, which can timely discover and correct problems in the design to ensure that the performance of the structure meets the requirements. The parameter optimization design can further improve the stability and efficiency of the structure, so that it can maintain the best working state under various working conditions.

[0062] Example 2: Taking the upstream water diversion system of a power station as an example, the water diversion flow rate is 98.8m³ / s. The installation elevation of the unit is used as the reference elevation. The water level of the reservoir is The elevation of the bottom of the connecting pipe 3 on the surge chamber structure is 750m. The length of the water diversion tunnel 4 is 28 km, and the diameter of the water diversion tunnel 4 is 6 m; the length of the pressure pipe 5 is 1 km, and the diameter of the pressure pipe 5 is 5 m. The height of the shaft 1 is =161m, the height of the connecting pipe 3 is =3m, the total height of the surge chamber structure is =164m, the length of the connecting pipe 3 is 3m.

[0063] (1) Determine the cross-sectional area F of the shaft 1;

[0064] The cross-sectional area of ​​the shaft 1 is calculated according to the Thomas critical cross-sectional area formula. 17.85m², then the cross-sectional area of ​​the shaft 1 is Satisfies the following relationship: , where K is 4; the calculation results are 71.4m², through conversion, the cross-sectional diameter of shaft 1 is 9.535m. In order to meet the design requirements, the cross-sectional diameter of shaft 1 is rounded to 10m. Through conversion, the stable cross-sectional area of ​​shaft 1 is obtained. 78.54m².

[0065] (2) Calculating the size of the connecting pipe 3;

[0066] The cross-sectional area of ​​the diversion tunnel 4 is 28.27m², then the cross-sectional area of ​​the connecting pipe 3 is , satisfying the following relationship: , taking the value of 45%, the area of ​​the cross section of the connecting pipe 3 is calculated 12.72m²; the length of the connecting pipe 3 is 3 m.

[0067] (3) Designing the dimensions of the upper chamber 21, the middle chamber 22, and the lower chamber 23;

[0068] The length a of the rectangular structure at the inlet end of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is 8 m, the height b is 10 m, and the radius of the semicircular structure of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is 4m, the length L of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is 240, and the slope of the top plate and the bottom plate of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is 1.5% and 1%, and 0< <2% and <2%, then the height of the tail end rectangular structure of the upper chamber 21, the middle chamber 22 and the lower chamber 23 is They satisfy the following relations respectively: =10-240×0.015-240×0.01=4m.

[0069] (4) Determining the positions of the upper chamber 21, the middle chamber 22, and the lower chamber 23;

[0070] The position of the upper chamber 21 is determined by the water level of the reservoir =750m, the water level in the surge chamber is flush with the reservoir water level after the unit is shut down, ensuring that the reservoir water level is slightly higher than the bottom plate height of the upper chamber 21, and the height from the bottom plate at the inlet end of the upper chamber 21 to the upper surface of the water diversion tunnel 4 =149m, the height from the horizontal plane in the upper chamber 21 to the bottom plate of the upper chamber 21 is the submerged depth of the upper chamber 21 , and the upper chamber 21 is submerged to a depth of Below 4.67m, the submerged depth of the upper chamber 21 is =750-600-149=1m, the height of the upper chamber 21 must ensure that the safety excess height above the highest surge water level is not less than 1m. The design of the upper chamber 21 can ensure that the upper chamber 21 plays the best regulating role in the surge chamber structure while maintaining the stability and reliability of the structure.

[0071] The position of the lower chamber 23 is determined by the water level of the reservoir =750m and head loss when all units are running at rated conditions and steady state =37.8m, ensuring that the water level in the lower chamber 23 is slightly higher than the bottom plate height of the lower chamber 23, and the height from the bottom plate at the inlet end of the lower chamber 23 to the upper surface of the water diversion tunnel 4 =108m, the height from the horizontal plane in the lower chamber 23 to the bottom plate of the lower chamber 23 is the submerged depth of the lower chamber 23 , and the submerged depth of the lower chamber 23 is Below 4.67m, the submerged depth of the lower chamber 23 is =750-600-37.8-108=4.2m, the bottom of the lower chamber 23 is lower than the lowest surge water level. Reasonable setting of the position of the lower chamber 23 ensures that the lower chamber 23 can play the best regulating role during the pressure regulation process while maintaining the stability and reliability of the structure.

[0072] The middle chamber 22 is located between the upper chamber 21 and the lower chamber 23. The height between the top plate of the middle chamber 22 and the bottom plate of the upper chamber 21 is =5m, the height between the bottom plate of the middle chamber 22 and the top plate of the lower chamber 23 =8m, .

[0073] The height of the shaft 1 is , the top height of the shaft 1 should be higher than the inlet top plate of the upper chamber 21 by at least 1m, and the value in this embodiment is 1m, therefore, =161 m; the height of the connecting pipe 3 is =3 m, the total height of the surge chamber structure =164 m.

[0074] (5) Design a new surge chamber structure based on the cross-sectional area F of the shaft 1, the cross-sectional area S of the connecting pipe 3, the sizes of the upper chamber 21, the middle chamber 22 and the lower chamber 23, and the positions of the upper chamber 21, the middle chamber 22 and the lower chamber 23, and verify the hydraulic characteristics of the new surge chamber structure;

[0075] After the new surge chamber structure design is completed, the hydraulic characteristics of the new body are verified by a one-dimensional numerical calculation method, and the hydraulic characteristics of the surge chamber body under load rejection and load increase are calculated. The calculation results are as follows Figure 6 As shown;

[0076] Depend on Figure 6 It can be seen that when the unit is in load-shedding condition, since the horizontal cross-sectional area of ​​each chamber is much larger than the cross-sectional area of ​​the shaft 1, the water level rises in a step-like pattern under the influence of the upper chamber 21, the middle chamber 22 and the lower chamber 23, and the water level waveform in each chamber area is relatively horizontal. The maximum surge amplitude of the three-chamber surge chamber is 158.2m, and with the passage of time, the water level fluctuation in the surge chamber gradually tends to be flat. When the load is increased, the water level in the three-chamber surge chamber decreases in a step-like pattern, and the water level in the surge chamber reaches stability at a relatively fast speed, and there is no obvious oscillation phenomenon in the process. Therefore, the three-chamber water chamber surge chamber structure designed in this example has achieved good results in suppressing water level fluctuations. It can be considered that its hydraulic characteristics are good and the design is reasonable.

[0077] Depend on Figure 7 It can be seen that the structure and layout of the double-chamber surge chamber in the figure are the same as those of the three-chamber surge chamber, and their cavity structures are all gradual structures. The only difference is that the double-chamber surge chamber has no middle chamber. The surge amplitude fluctuation line of the double-chamber surge chamber is obtained by calculation. It can be concluded from the fluctuation line that the surge amplitude of the double-chamber surge chamber fluctuates greatly, while the surge amplitude of the three-chamber surge chamber fluctuates slowly. The surge amplitude fluctuation line of the double-chamber surge chamber is compared with the surge amplitude fluctuation line of the three-chamber surge chamber. The three-chamber surge chamber is better than the double-chamber surge chamber in suppressing the maximum surge amplitude.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-chamber water chamber type surge chamber structure, characterized in that: It includes a vertical shaft, the side wall of the upper end of the vertical shaft is connected with a chamber structure, the chamber structure includes an upper chamber, a middle chamber and a lower chamber, the upper chamber, the middle chamber and the lower chamber are vertically connected in sequence on one side of the side wall of the vertical shaft, the upper chamber, the middle chamber and the lower chamber are respectively gradual structures, and the size of the inlet end of the upper chamber, the middle chamber and the lower chamber is larger than the size of the tail end, and the lower end of the vertical shaft is connected with a connecting pipe for connecting to a water diversion tunnel.

2. The three-chamber water chamber type surge chamber structure according to claim 1 is characterized in that: The cross-sections of the upper chamber, the middle chamber and the lower chamber are respectively door-shaped, the upper parts of the cross-sections of the upper chamber, the middle chamber and the lower chamber are respectively semicircular structures, and the lower parts are rectangular structures, the areas of the rectangular structures of the upper chamber, the middle chamber and the lower chamber from the inlet end to the tail end are successively reduced, and the radius of the semicircular structures of the upper chamber, the middle chamber and the lower chamber from the inlet end to the tail end remains unchanged.

3. The three-chamber water chamber type surge chamber structure according to claim 1 is characterized in that: The cross-sectional area of ​​the shaft is calculated according to Thomas' critical cross-sectional area formula. Satisfies the following relationship: , where K is the coefficient, and ; is the critical cross-sectional area of ​​Thomas.

4. The three-chamber water chamber type surge chamber structure according to claim 1 is characterized in that: The cross-sectional area of ​​the diversion tunnel is , then the cross-sectional area of ​​the connecting pipe is , satisfying the following relationship: , and the cross-sectional area of ​​the connecting pipe The cross-sectional area of ​​the shaft Satisfies the following relationship, < .

5. The three-chamber water chamber type surge chamber structure according to claim 1 is characterized in that: The lengths of the rectangular structures at the inlet ends of the upper chamber, the middle chamber and the lower chamber are respectively a and b, and the radii of the semicircular structures of the upper chamber, the middle chamber and the lower chamber are respectively The lengths of the upper chamber, the middle chamber and the lower chamber are L respectively, and the slopes of the top plate and the bottom plate of the upper chamber, the middle chamber and the lower chamber are and , and 0< <2% and <2%, then the height of the rectangular structure of the upper chamber, the middle chamber and the tail end of the lower chamber , respectively satisfying the following relations: .

6. A three-chamber water chamber type pressure regulating chamber structure according to claim 1, characterized in that: The length of the connecting pipe is , the elevation of the bottom of the connecting pipe is The water level of the reservoir is The height from the bottom plate of the upper chamber inlet to the upper surface of the water diversion tunnel is The height from the horizontal plane in the upper chamber to the bottom plate of the upper chamber is the submerged depth of the upper chamber. , then the upper chamber submergence depth Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the upper chamber, and R is the radius of the semicircular structure at the inlet end of the upper chamber.

7. The three-chamber water chamber type pressure regulating chamber structure according to claim 1 is characterized in that: The head loss when all units are running at rated conditions and in steady state is: The height from the bottom plate of the lower chamber inlet to the upper surface of the water diversion tunnel is The height from the horizontal plane in the lower chamber to the bottom plate of the lower chamber is the submerged depth of the lower chamber. , then the submerged depth of the lower chamber is Satisfies the following relationship: , , where is the height of the rectangular structure at the inlet end of the lower chamber, and R is the radius of the semicircular structure at the inlet end of the lower chamber.

8. The three-chamber water chamber type pressure regulating chamber structure according to claim 1 is characterized in that: The vertical height between the top plate of the middle chamber and the bottom plate of the upper chamber is , the vertical height between the bottom plate of the middle chamber and the top plate of the lower chamber is ,but .

9. The three-chamber water chamber type surge chamber structure according to claim 1 is characterized in that: After the design of the surge chamber structure is completed, the hydraulic characteristics of the surge chamber structure are verified by a one-dimensional numerical calculation method.

10. The hydraulic design method of a three-chamber water chamber type surge chamber structure according to claim 1, characterized in that: The hydraulic design method comprises the following steps: Determine the cross-sectional area F of the shaft; Calculating the size of the connecting pipe; Designing the sizes of the upper chamber, the middle chamber, and the lower chamber; determining positions of the upper chamber, the middle chamber, and the lower chamber; A new pressure regulating chamber structure is designed based on the cross-sectional area F of the shaft, the shape of the connecting pipe, the sizes of the upper chamber, the middle chamber and the lower chamber, and the positions of the upper chamber, the middle chamber and the lower chamber, and the hydraulic characteristics of the new pressure regulating chamber structure are verified.

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