Pump storage power station shaft type water inlet and outlet gate system

Abstract

The application provides a vertical shaft type water inlet and outlet gate system of pumped storage power station and belongs to the technical field of water conservancy safety control. The vertical shaft type water inlet and outlet gate system comprises a cylindrical gate, a closed shaft, a trash rack section, a diffusion section, a straight pipe section, a bend pipe section and a tunnel section which are sequentially arranged along the direction of power generation water flow of the cylindrical gate vertical shaft type water inlet and outlet gate. The trash rack section has a horn section at one end, and the trash rack section is provided with a cover plate, a splitter pier and a trash rack. The lower part of the cover plate of the trash rack section is connected with the splitter pier. The center of the cover plate is excavated. The trash rack is provided with an orifice which serves as a water inlet and outlet orifice. The bend pipe section is connected with a water diversion tunnel. The gate is a cylindrical gate which is arranged above the water inlet and outlet gate and is connected with the upper and lower parts. The bottom of the gate is fixed with the inner surface of the concrete of the horn section, and the top of the gate is fixed with the cover plate of the trash rack section. The gate is connected with the closed shaft through the splitter pier wall and is fixed. The application can reduce the construction difficulty and improve the maintenance convenience.

Description

Technical Field

[0001] This invention relates to the field of water conservancy safety control technology, and in particular to a vertical shaft inlet and outlet gate system for a pumped storage power station. Background Technology

[0002] The gate shaft type intake is a structural form of intake for pumped storage power stations. Its characteristic feature is that the gate is located inside a vertical shaft within the mountain, with a tunnel section connecting the inlet to the gate shaft. This structural form is included in the Chinese power industry standard "DL / T 5398—2007 Design Code for Hydropower Station Intakes". The shaft top is equipped with opening and closing equipment and a gate hoisting room, the funnel-shaped inlet is located on the bank slope, and the flow channel is generally for pressurized water flow.

[0003] Based on structural characteristics, it can be divided into two types: wet well (pressure tunnel planar gate vertical well, with water after the gate is closed) and dry well (non-pressure tunnel arc gate vertical well, with no water after the gate is closed). This structure has the advantages of saving working bridges and good seismic stability, but it has the disadvantages of difficult vertical well excavation and inconvenient maintenance. It is suitable for engineering scenarios where the riverbank rock is firm and there is no risk of collapse when excavating the vertical well.

[0004] Existing gates are usually located inside vertical shafts in the mountains, with the entrance and gate shaft connected by a tunnel section. This arrangement has the problems of high investment, difficult construction, and inconvenient maintenance of the tunnel in the later stages. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a vertical shaft inlet and outlet gate system for pumped storage power stations. The purpose is to provide an arrangement scheme and an optimal shape scheme for the cylindrical gate, thereby reducing investment and construction difficulty and improving maintenance convenience.

[0006] This invention provides a vertical shaft inlet and outlet gate system for a pumped storage power station. The vertical shaft inlet and outlet of the cylindrical gate are arranged in sequence along the power generation water flow direction, including a closed shaft, a trash rack section, a diffuser section, a straight pipe section, a bend pipe section, and a tunnel section. A cylindrical gate is installed at the upper end of the closed shaft. One end of the trash rack section is a funnel-shaped section. The trash rack section is equipped with a cover plate, a diversion pier, and a trash rack. The trash rack has openings as inlet and outlet openings. The lower part of the cover plate of the trash rack section is connected to the diversion pier. A hole is dug in the center of the cover plate. The gate is a cylindrical gate, located above the inlet and outlet. The gate is connected vertically, with the bottom fixed to the inner surface of the funnel-shaped concrete section and the top fixed to the cover plate of the trash rack section. The gate is connected and fixed to the enclosed well shaft by diversion pier walls.

[0007] Preferably, the cover plate has a planar shape that is an inscribed regular polygon of a circle.

[0008] Preferably, the cover plate is an inscribed regular decagon with a radius of 10.5m.

[0009] Preferably, the thickness is 1.4-1.6 mm, and the diameter of the hole in the center of the cover plate is 8 mm.

[0010] Preferably, the thickness is 1.5m.

[0011] Preferably, the hole at the center of the cover plate has the same diameter as the cylindrical gate.

[0012] Preferably, the hole diameter of the cover plate is greater than 2 / 3 of the outer diameter of the cover plate, which is beneficial to improving the flow pattern inside the outlet and the cross-section of the trash rack.

[0013] Preferably, 8-12 diversion piers are provided.

[0014] Preferably, 10 diversion piers are provided.

[0015] Preferably, the diversion pier is 1.2-1.8m wide and has a semi-circular shape at both ends.

[0016] Preferably, the diversion pier is 1.5m wide.

[0017] Preferably, the opening of the trash rack is trapezoidal and 3.8-4m high.

[0018] Preferably, the trapezoidal height of the trash rack opening is 3.9m.

[0019] Preferably, the diversion pier is flush with the inner wall of the enclosed well.

[0020] Preferably, the inner diameter of the sealed wellbore is 18.6-19.0m.

[0021] Preferably, the inner diameter of the sealed wellbore is 18.8m.

[0022] Preferably, a base plate is provided at the bottom of the inlet and outlet.

[0023] Preferably, the boundary curve of the diffusion section can gradually transform the funnel-shaped section into a vertical shaft pipe, which is connected to the bottom plate of the inlet and outlet; the bend section is followed by the water diversion tunnel.

[0024] Preferably, the boundary curve of the diffusion section is a quarter elliptical curve, through which the funnel mouth gradually transforms into a circular vertical shaft pipe.

[0025] Preferably, the major semi-axis of the ellipse is 28.4-28.8m and the minor semi-axis is 7-8m. Through this elliptical curve, the 19-19.4m diameter bell mouth gradually transforms into a 6.6-7m diameter vertical shaft pipe.

[0026] Preferably, the major semi-axis of the ellipse is 28.6m and the minor semi-axis is 7.345m. This elliptical curve gradually transforms the 19.2m diameter flared opening into a 6.8m diameter vertical shaft pipe.

[0027] Preferably, a slot is provided in the diffusion section, which is a ring structure. A water-stop sealing structure is arranged around the slot. When the cylindrical gate is closed, the bottom of the cylindrical gate coincides with the bottom of the slot. At this time, the water in the vertical shaft and the water in the reservoir do not flow between them.

[0028] Preferably, the slot width is not less than 0.5m.

[0029] Preferably, it has a straight pipe section of not less than 5m.

[0030] Preferably, the straight pipe section is 19.91m long.

[0031] Preferably, the centerline of the bend has a turning angle of 90°, and the inner diameter of the bend connecting to the water diversion tunnel is 8.2-8.6m.

[0032] Preferably, the radius of the bend centerline is 12m, and the inner diameter of the bend connecting to the water diversion tunnel is 8.40m.

[0033] Preferably, the diversion pier is an extended diversion pier, and at least three are provided.

[0034] Preferably, the dead water level is 571m, and the normal storage water level is 606m; the single-unit flow rate for power generation at the dead water level is 91.9m³ / h. 3 / s, single pumping unit flow rate 80m³ / s 3 / s; Normal water level generator single unit flow rate: 82.3m³ / s 3 / s, single pump flow rate 60.1m³ / s 3 / s.

[0035] Preferably, the diameter of the cylindrical gate is 10m-11m.

[0036] Preferably, the diameter of the cylindrical gate is 10.5m.

[0037] Preferably, the cylindrical gate design scheme is verified by the following method: Based on the arrangement of the inlet and outlet of the cylindrical gate, and considering the influence of boundary conditions, the calculation area is determined as follows: The calculation area includes: part of the reservoir area, cylindrical gate, all orifices, diffuser section, straight pipe section, and water diversion tunnel section; A 300m ring of water around the inlet and outlet is taken as the boundary of the reservoir area, and the tunnel section is extended by another 200m as the tunnel boundary. During pumping operation, water flows from the tunnel section to the reservoir: at the tunnel boundary, the inflow velocity is given according to the flow rate; at the reservoir boundary, the water level is set according to the hydrostatic pressure; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free liquid surface. During power generation, the water flows from the reservoir to the tunnel section: the water level at the reservoir boundary is set according to the static water pressure; the outflow velocity at the tunnel boundary is given according to the flow rate; the solid wall boundary adopts a no-slip condition; and the reservoir liquid surface is a free liquid surface.

[0038] Preferably, during the verification process, time-averaged continuity equations and motion equations are used, a turbulence model is selected, and mathematical models of the inlet and outlet are established to conduct numerical simulations of their hydraulic characteristics.

[0039] Preferably, the equations used in the verification process include: Continuity equation:

[0040] Reynolds equation:

[0041] k equation:

[0042] ε equation:

[0043] In the formula, and The average velocity over time; t For time; The density of the liquid; Pressure; The coefficient of dynamic viscosity; For Reynolds stress, , It is the Kronecker symbol, when i = j hour =1, when i≠j hour =0; This refers to the volume force acting on a unit mass of water. It is the kinetic energy per unit mass of turbulent motion; ν It is the kinematic viscosity coefficient; The viscosity coefficient of turbulent flow is determined by the turbulent kinetic energy. k and turbulent kinetic energy dissipation rate ε Sure, ; G The term generated by the cut is expressed as follows: ; εThe turbulent kinetic energy dissipation rate; C μ C 1ε C 2ε and σ ε These are the model's general constants, taken as 0.09, 1.44, 1.92, and 1.30, respectively.

[0044] Preferably, the mathematical model of the inlet and outlet is solved using the finite volume method, the spatial discretization scheme is a second-order upwind scheme, the pressure and velocity coupling solution is solved using the SIMPLE algorithm, and the free surface tracking is performed using the VOF method. The VOF method introduces a volume fraction variable for each phase. α q The phase interface is determined by solving for the volume fraction values ​​within each control unit. Let the first phase be the volume fraction value within a certain control unit. q Phase volume fraction is α q (0≤ α q ≤1), then when α q When =0, there is no first in the control unit. q Phase fluid; α q When =1, the control unit is filled with the first... q Phase fluid; 0< α q When the value is less than 1, the control unit includes a phase interface, and the sum of the volume fractions of each phase within each control unit equals 1, i.e.

[0045] α q The following equations should be satisfied:

[0046] The calculation of the surface volume flux of all control units in the calculation adopts an implicit difference scheme, i.e.

[0047] In the formula, n +1 is the indicator factor for the current time step; n This is an indicator factor for the previous time step; α q，f For the first unit surface q Calculated value of phase volume fraction; V For the volume of the control unit; U f This refers to the volumetric flux of the control unit surface.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention relates to a cylindrical gate shaft-type inlet and outlet system. Along the direction of the power generation water flow, the system sequentially comprises a cylindrical gate, a closed shaft, a trash rack section, a diffuser section, a straight pipe section, a curved pipe section, and a tunnel section. One end of the trash rack section is a funnel-shaped section. The trash rack section includes a cover plate, a diversion pier, and a trash rack. The lower part of the cover plate is connected to the diversion pier. A hole is drilled in the center of the cover plate. The trash rack has openings serving as inlet and outlet openings. A base plate is provided at the bottom of the inlet and outlet. The boundary curve of the diffuser section gradually transforms the funnel-shaped section into a vertical shaft pipe, connecting to the base plate of the inlet and outlet. The curved pipe section is followed by a water diversion tunnel. The gate is a cylindrical gate, positioned above the inlet and outlet, with the gate's top and bottom connected. The bottom of the gate is fixed to the inner surface of the funnel-shaped section's concrete, and the top of the gate is fixed to the cover plate of the trash rack section. The gate is connected and fixed to the closed shaft via diversion pier walls. During construction, the cylindrical gate only needs to be placed on the top of the enclosed shaft, without needing to install the cylindrical gate inside the vertical shaft of the mountain. This can still meet the hydraulic requirements, with low investment, low construction difficulty, and convenient tunnel maintenance in the later stage. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0050] Figure 1 This is a plan view of the cylindrical gate body of the vertical shaft inlet and outlet water in an embodiment of the present invention; Figure 2 This is a cross-sectional view of a vertical shaft-type inlet / outlet cylindrical gate according to an embodiment of the present invention; Figure 3 A comparative diagram of the body shape of vertical shaft inlet and outlet water inlets with different cylindrical gate diameters according to an embodiment of the present invention; Figure 4 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the horizontal section (AA) effect diagram of the flow velocity field of the vertical shaft inlet and outlet under pumping conditions is shown. Figure 5 In the verification of the cylindrical design scheme of an embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the vertical cross-sectional effect of the flow velocity field of the vertical shaft inlet and outlet under pumping conditions is shown in the figure. Figure 6 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the cross-sectional effect diagram of the trash rack of the vertical shaft inlet and outlet flow field under pumping conditions is shown. Figure 7In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the flow velocity distribution diagram of the cross-section of the trash rack at the inlet and outlet of the pumping operation is shown. Figure 8 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the horizontal section (AA) effect diagram of the flow velocity field of the vertical shaft inlet and outlet under power generation conditions is shown. Figure 9 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the vertical cross-sectional effect of the flow velocity field of the vertical shaft inlet and outlet under power generation conditions is shown in the figure. Figure 10 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the cross-sectional effect diagram of the flow velocity field of the vertical shaft inlet and outlet of the power generation operation is shown. Figure 11 In the verification of the cylindrical design scheme of one embodiment of the present invention, the diameter of the cylindrical gate is 11m, and the flow velocity distribution diagram of the cross-section of the trash rack at the inlet and outlet of the power generation operation is shown. Figure 12 This is a diagram of the cylindrical gate shaft inlet / outlet in a hydraulic characteristic analysis according to an embodiment of the present invention.

[0051] In the diagram, 1-cylindrical gate, 2-enclosed shaft, 3-diversion pier, 4-diffusion section, 5-straight pipe section, 6-bend pipe section, 7-tunnel section, 8-diversion pier wall, 9-cover plate, 10-slot, 11-vertical shaft. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in detail below.

[0053] like Figures 1-2 As shown, the present invention provides a vertical shaft inlet and outlet gate system for a pumped storage power station. The vertical shaft inlet and outlet of the cylindrical gate is arranged in sequence along the power generation water flow direction, including a closed shaft 2, a trash rack section, a diffuser section 4, a straight pipe section 5, a bend section 6, and a tunnel section 7. A cylindrical gate 1 is set at the upper end of the closed shaft 2. One end of the trash rack section is a funnel-shaped section. The trash rack section is equipped with a cover plate 9, a diversion pier 3, and a trash rack. The trash rack has openings as inlet and outlet openings. The lower part of the cover plate 9 of the trash rack section is connected to the diversion pier 3. A hole is dug in the center of the cover plate 9. The gate adopts a cylindrical gate 1, which is arranged above the inlet and outlet. The gate is connected from top to bottom. The bottom of the gate is fixed to the inner surface of the concrete of the funnel section, and the top of the gate is fixed to the cover plate 9 of the trash rack section. The gate is connected and fixed to the enclosed well 2 through the diversion pier wall 8.

[0054] In a specific embodiment of the present invention, preferably, the planar shape of the cover plate 9 is an inscribed regular polygon of a circle.

[0055] In a specific embodiment of the present invention, preferably, the planar shape of the cover plate 9 is an inscribed regular decagon with a radius of 10.5m.

[0056] In a specific embodiment of the present invention, preferably, the thickness is 1.4-1.6m, and the diameter of the hole in the center of the cover plate 9 is 8m.

[0057] In one specific embodiment of the present invention, preferably, the thickness is 1.5m.

[0058] In a specific embodiment of the present invention, preferably, the hole at the center of the cover plate 9 has the same diameter as the cylindrical gate.

[0059] In a specific embodiment of the present invention, preferably, the hole diameter of the cover plate 9 is greater than 2 / 3 of the outer diameter of the cover plate 9, which is beneficial to improving the flow state inside the outlet and the cross-section of the trash rack.

[0060] In a specific embodiment of the present invention, preferably, 8-12 diversion piers 3 are provided.

[0061] In a specific embodiment of the present invention, preferably, 10 diversion piers 3 are provided.

[0062] In a specific embodiment of the present invention, preferably, the diversion pier 3 is 1.2-1.8m wide and has a semi-circular shape at both ends.

[0063] In a specific embodiment of the present invention, preferably, the diversion pier 3 is 1.5m wide.

[0064] In a specific embodiment of the present invention, preferably, the opening of the trash rack is trapezoidal and 3.8-4m high.

[0065] In one specific embodiment of the present invention, preferably, the trapezoidal height of the trash rack opening is 3.9m.

[0066] In a specific embodiment of the present invention, preferably, the diversion pier 3 is flush with the inner wall of the closed well.

[0067] In a specific embodiment of the present invention, preferably, the inner diameter of the sealed wellbore 2 is 18.6-19.0m.

[0068] In a specific embodiment of the present invention, preferably, the inner diameter of the sealed wellbore 2 is 18.8m.

[0069] In a specific embodiment of the present invention, preferably, a bottom plate is provided at the bottom of the inlet and outlet; In a specific embodiment of the present invention, preferably, the boundary curve of the diffusion section 4 can gradually transform the funnel section into a vertical shaft pipe, which is connected to the bottom plate of the inlet and outlet; the bend section 6 is connected to the water diversion tunnel.

[0070] In a specific embodiment of the present invention, preferably, the boundary curve of the diffusion section 4 is a 1 / 4 elliptical curve through which the flared opening gradually transforms into a circular vertical shaft pipe.

[0071] In a specific embodiment of the present invention, preferably, the major semi-axis of the ellipse is 28.4-28.8m and the minor semi-axis is 7-8m. Through this elliptical curve, the 19-19.4m diameter bell mouth gradually transforms into a 6.6-7m diameter vertical shaft pipe.

[0072] In a specific embodiment of the present invention, preferably, the major semi-axis of the ellipse is 28.6m and the minor semi-axis is 7.345m, and the elliptical curve gradually transforms the 19.2m diameter flared opening into a 6.8m diameter vertical shaft pipe.

[0073] In a specific embodiment of the present invention, preferably, a slot 10 is provided in the diffusion section, which is a ring structure. A water-stop sealing structure is arranged around the slot 10. When the cylindrical gate is closed, the bottom of the cylindrical gate coincides with the bottom of the slot 10. At this time, the water in the vertical shaft and the water in the reservoir do not flow between each other.

[0074] In a specific embodiment of the present invention, preferably, the width of the card slot 10 is not less than 0.5m.

[0075] In a specific embodiment of the present invention, preferably, a straight pipe section 5 of not less than 5m is provided.

[0076] In one specific embodiment of the present invention, preferably, the straight pipe section 5 is 19.91m long.

[0077] In a specific embodiment of the present invention, preferably, the centerline rotation angle of the bend section 6 is 90°, and the inner diameter of the bend section 6 connecting with the water diversion tunnel is 8.2-8.6m.

[0078] In a specific embodiment of the present invention, preferably, the turning centerline radius of the bend section 6 is 12m, and the inner diameter of the part where the bend section 6 connects with the water diversion tunnel is 8.40m.

[0079] In a specific embodiment of the present invention, preferably, the diversion pier 8 is an extended diversion pier, and at least 3 are provided.

[0080] In a specific embodiment of the present invention, preferably, the dead water level is 571m, the normal storage water level is 606m, and the single-unit flow rate of the generator at the dead water level is 91.9m³ / h. 3 / s, single pumping unit flow rate 80m³ / s 3 / s; Normal water level generator single unit flow rate: 82.3m³ / s 3 / s, single pump flow rate 60.1m³ / s 3 / s.

[0081] In a specific embodiment of the present invention, preferably, the diameter of the cylindrical gate 1 is 10m-11m.

[0082] In a specific embodiment of the present invention, preferably, the diameter of the cylindrical gate 1 is 10.5m.

[0083] In a specific embodiment of the present invention, the design scheme of the cylindrical gate 1 is preferably verified by the following method: Based on the inlet and outlet arrangement of the cylindrical gate 1, and considering the influence of boundary conditions, the calculation area is determined as follows: The calculation area includes: part of the reservoir area, cylindrical gate 1, all orifices, diffuser section 4, straight pipe section 5, and water diversion tunnel section; A 300m ring of water around the inlet and outlet is taken as the boundary of the reservoir area, and the tunnel section of straight pipe 5 is extended by another 200m as the tunnel boundary. During pumping operation, water flows from tunnel section 7 to the reservoir: at the tunnel boundary, the inflow velocity is given according to the flow rate; at the reservoir boundary, the water level is set according to the hydrostatic pressure; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free liquid surface. During power generation, the water flows from the reservoir to tunnel section 7: the water level at the reservoir boundary is set according to the static water pressure; the outflow velocity at the tunnel boundary is given according to the flow rate; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free liquid surface.

[0084] In a specific embodiment of the present invention, preferably, during the verification process, time-averaged continuity equations and motion equations are used, a turbulence model is selected, a mathematical model of the inlet and outlet is established, and its hydraulic characteristics are numerically simulated.

[0085] Example 1 The pumped storage power station shaft-type inlet and outlet gate system of the present invention will be described in detail below according to a specific embodiment of the present invention.

[0086] This invention provides a vertical shaft inlet and outlet gate system for a pumped storage power station. The vertical shaft inlet and outlet of the cylindrical gate are arranged sequentially along the power generation water flow direction as follows: cylindrical gate 1, enclosed shaft 2, trash rack section, diffuser section 4, straight pipe section 5, bend pipe section 6, and tunnel section 7. One end of the trash rack section is a funnel-shaped section. The trash rack section is equipped with a cover plate 9, a diversion block 3 and a trash rack. The lower part of the cover plate 9 of the trash rack section is connected to the diversion block 3; a hole is dug in the center of the cover plate 9. The trash rack is equipped with openings, which serve as inlet and outlet openings; A base plate is installed at the bottom of the inlet and outlet; The boundary curve of the diffusion section 4 can gradually transform the funnel section into a vertical shaft pipe, which is connected to the bottom plate of the inlet and outlet; the bend section 6 is connected to the water diversion tunnel. The gate adopts a cylindrical gate 1, which is arranged above the inlet and outlet. The gate is connected from top to bottom. The bottom of the gate is fixed to the inner surface of the concrete of the funnel section, and the top of the gate is fixed to the cover plate 9 of the trash rack section. The gate is connected and fixed to the enclosed well 2 through the diversion pier wall 8.

[0087] In this embodiment, preferably, the cover plate 9 is an inscribed regular decagon with a radius of 11m and a thickness of 1.5m, and the diameter of the hole in the center of the cover plate 9 is 8m.

[0088] In this embodiment, preferably, 10 diversion piers 3 are provided.

[0089] In this embodiment, preferably, the diversion pier 3 is 1.5m wide.

[0090] In this embodiment, preferably, the trapezoidal height of the trash rack opening is 3.9m.

[0091] In this embodiment, preferably, the inner diameter of the sealed wellbore 2 is 18.8m.

[0092] In this embodiment, preferably, the boundary curve of the diffusion section 4 is a quarter elliptic curve with a major semi-axis of 28.6m and a minor semi-axis of 7.345m. This elliptic curve gradually transforms the 19.2m diameter bell mouth into a 6.8m diameter vertical shaft pipe.

[0093] In this embodiment, preferably, the straight pipe section 5 is 19.91m long.

[0094] In this embodiment, preferably, the centerline turning angle of the bend section 6 is 90°, the turning centerline radius of the bend section 6 is 12m, and the inner diameter of the part where the bend section 6 connects with the water diversion tunnel is 8.40m.

[0095] In this embodiment, preferably, the diversion pier 8 is an extended diversion pier, and at least 3 are provided.

[0096] In this embodiment, preferably, the dead water level is 571m and the normal storage water level is 606m; the single-unit flow rate of the generator at the dead water level is 91.9m³ / h. 3 / s, single pumping unit flow rate 80m³ / s 3 / s; Normal water level generator single unit flow rate: 82.3m³ / s 3 / s, single pump flow rate 60.1m³ / s 3 / s.

[0097] In this embodiment, the design scheme of the cylindrical gate 1 is verified by selecting a diameter of 11m.

[0098] In this embodiment, during the verification process of the cylindrical gate 1 design scheme, time-averaged continuity equations and motion equations are adopted, a turbulence model is selected, and mathematical models of the inlet and outlet are established to conduct numerical simulation of its hydraulic characteristics.

[0099] Preferably, the equations used in the verification process include: Continuity equation:

[0100] Reynolds equation:

[0101] k equation:

[0102] ε equation:

[0103] In the formula, and The average velocity over time; t For time; The density of the liquid; Pressure; The coefficient of dynamic viscosity; For Reynolds stress, , It is the Kronecker symbol, when i = j hour =1, when i≠j hour =0; This refers to the volume force acting on a unit mass of water. It is the kinetic energy per unit mass of turbulent motion; ν It is the kinematic viscosity coefficient; The viscosity coefficient of turbulent flow is determined by the turbulent kinetic energy. k and turbulent kinetic energy dissipation rate ε Sure, ; G The term generated by the cut is expressed as follows: ; ε The turbulent kinetic energy dissipation rate; C μ C 1ε C 2ε and σ ε These are the model's general constants, taken as 0.09, 1.44, 1.92, and 1.30, respectively.

[0104] Preferably, the mathematical model of the inlet and outlet is solved using the finite volume method, the spatial discretization scheme is a second-order upwind scheme, the pressure and velocity coupling solution is solved using the SIMPLE algorithm, and the free surface tracking is performed using the VOF method. The VOF method introduces a volume fraction variable for each phase. α q The phase interface is determined by solving for the volume fraction values ​​within each control unit. Let the first phase be the volume fraction value within a certain control unit. q Phase volume fraction is α q (0≤ α q ≤1), then when α q When =0, there is no first in the control unit. q Phase fluid; α q When =1, the control unit is filled with the first... q Phase fluid; 0< α q When the value is less than 1, the control unit includes a phase interface, and the sum of the volume fractions of each phase within each control unit equals 1, i.e.

[0105] α q The following equations should be satisfied:

[0106] The calculation of the surface volume flux of all control units in the calculation adopts an implicit difference scheme, i.e.

[0107] In the formula, n +1 is the indicator factor for the current time step; n This is an indicator factor for the previous time step; α q，f For the first unit surface q Calculated value of phase volume fraction; V For the volume of the control unit; U f This refers to the volumetric flux of the control unit surface.

[0108] To verify the feasibility of arranging the cylindrical gate 1 at the vertical shaft inlet / outlet, a design scheme with a diameter of 11m for the cylindrical gate 1 was calculated. The flow regime inside the inlet / outlet and the closed shaft 2, the velocity distribution of the trash rack cross section, and the head loss at the inlet / outlet were studied.

[0109] From a hydraulic perspective, a comprehensive analysis of the inlet and outlet design of the cylindrical gate 1 reveals the following problems: (1) When the water level is dead, the submerged water depth is small. When pumping (outflow), the flow velocity from the diffusion section 4 is large, and some water enters the closed well 2, which may cause water surface fluctuations. Therefore, it should be given special attention.

[0110] (2) When the water level is dead, the submerged water depth is small. When the power generation condition (inflow) is in progress, vortices may be generated in the closed well 2, so this should be given special attention.

[0111] Therefore, to address potential issues, under a dead water level of 571m, simulations were conducted using two pumping units (outflow, flow rate 2×80.0m³ / s) and two generator units (inflow, flow rate 2×91.9m³ / s) to study the flow regime at the inlet and outlet of the cylindrical gate 1 and inside the closed well 2, the velocity distribution across the trash rack cross-section, and the head loss at the inlet / outlet.

[0112] Based on the arrangement of the inlet and outlet of the cylindrical gate 1, and considering the influence of boundary conditions, the calculation area is determined. The calculation area includes: part of the reservoir area, cylindrical gate 1, all orifices, diffuser section 4, straight pipe section 5, and water diversion tunnel section. A 300m annular water area extending from the inlet / outlet into the reservoir area is taken as the reservoir area boundary, and the tunnel section 5 is extended by another 200m as the tunnel boundary.

[0113] During pumping operation (outflow), water flows from tunnel section 7 into the reservoir. The inflow velocity at the tunnel boundary is given according to the flow rate; the water level at the reservoir boundary is set according to the hydrostatic pressure; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free surface.

[0114] During power generation (inflow), the water flows from the reservoir to tunnel section 7. At the reservoir boundary, the water level is set based on the static pressure; at the tunnel boundary, the outflow velocity is given based on the flow rate; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free surface.

[0115] Table 1. Head loss and head loss coefficient at 11m inlet and outlet (pumping conditions)

[0116] Table 2. Head loss and head loss coefficient at 11m inlet and outlet (power generation condition)

[0117] In this embodiment, the vertical shaft inlet / outlet design uses a closed shaft 2 with an inner diameter of 18.8m, and the cover plate 9 is a regular decagon with an inner diameter of 21.292m. The closed shaft 2 is located on top of the cover plate 9 of the vertical shaft inlet / outlet and is connected and fixed to three extended diversion piers 8 around the cylindrical gate 1. Therefore, if the inner diameter of the closed shaft 2 is to be increased, its maximum inner diameter can be 20m.

[0118] The water level fluctuation inside the closed well 2 is mainly affected by the diameter of the top cover opening. The closed well 2 with an inner diameter of 18.8m is used. For vertical well inlets / outlets with different top cover opening diameters of 8m, 11m and 15m, the water level fluctuation inside the closed well 2 is small under all working conditions when operating at dead water level. The maximum water level difference inside the closed well 2 is 0.51m.

[0119] When operating at dead water level, with an inner diameter of 18.8m in sealed well 2, the water volume inside well 2 is 1249.12m³. 3 When the inner diameter of the sealed wellbore 2 increases to 20m, the water volume inside the sealed wellbore 2 is 1413.68m³. 3 The water volume inside the sealed well 2 increases by 13%, and the sidewall of the sealed cylinder only extends outward by 0.6m, thus having a relatively small impact on water surface fluctuations. Therefore, increasing the inner diameter of the sealed well 2 to 20m has little effect on reducing water surface fluctuations within the sealed well 2.

[0120] To verify the feasibility of arranging the cylindrical gate 1 at the vertical shaft inlet and outlet, under a dead water level of 571m, calculations were performed on the flow regime, velocity distribution across the trash rack cross-section, and head loss near the 11m diameter vertical shaft inlet / outlet of the cylindrical gate 1, considering both dual-unit pumping (outflow) and dual-unit power generation (inflow) operation. The verification results are shown in Tables 1-2, and... Figures 3-11 As shown.

[0121] ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.57m (dead water level 571m), the highest point is 571.68m, and the lowest point is 571.32m (maximum water surface elevation difference 0.36m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.47m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward velocity of 1.49 m / s and a maximum reverse velocity of -0.07 m / s. The reverse velocity range is within 0.47 m of the bottom plate, accounting for approximately 12.1% of the orifice height, with a velocity non-uniformity coefficient of 2.16~2.33. The head loss coefficient of the 11 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.36.

[0122] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity across the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 11 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0123] In summary, the 11m diameter cylindrical gate 1 of the vertical shaft inlet / outlet meets the specifications for hydraulic properties. The diameter of the cylindrical gate 1 has a significant impact on the hydraulic properties of the inlet / outlet under outflow conditions. Increasing the diameter helps reduce or even eliminate the reverse velocity zone at the bottom of the trash rack section, but it exacerbates water surface fluctuations within the sealed shaft 2 at the top of the cover plate 9, increasing head loss to some extent. The diameter of the cylindrical gate 1 has a smaller impact on the hydraulic properties of the inlet / outlet under inflow conditions and does not generate harmful air intake vortices. Therefore, the 11m diameter cylindrical gate 1 is selected as the preferred option, and a sensitivity analysis is further conducted regarding its diameter.

[0124] Using the preferred scheme with a diameter of 11m as the baseline, sensitivity analysis was conducted on five schemes with diameters of 10m, 10.5m, 11m, 11.5m and 12m to compare the nearby flow patterns, flow velocity distribution across the trash rack section and head loss at the inlet / outlet under the dual-unit pumping (outflow) and dual-unit power generation (inflow) conditions.

[0125] To investigate the influence of the diameter of the cylindrical gate 1 on the hydraulic characteristics of the vertical shaft inlet / outlet, under a dead water level of 571m, the flow regime, trash rack cross-section velocity distribution, and head loss near the vertical shaft inlet / outlet were calculated for dual-unit pumping (outflow) and dual-unit power generation (inflow) conditions, with cylindrical gate 1 diameters of 10, 10.5m, 11m, 11.5m, and 12m, respectively. Then, a sensitivity analysis was conducted on the influence of the cylindrical gate 1 diameter on the hydraulic characteristics of the vertical shaft inlet / outlet.

[0126] (1) The diameter of the cylindrical gate is 10m ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.56m (dead water level 571m), the highest point is 571.64m, and the lowest point is 571.38m (maximum water surface elevation difference 0.26m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.41m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward flow velocity of 1.52 m / s and a maximum reverse flow velocity of -0.08 m / s. The reverse flow velocity range is within 0.65 m of the bottom plate, accounting for approximately 16.77% of the orifice height, with a velocity non-uniformity coefficient of 2.20~2.38. The head loss coefficient of the 10 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.36.

[0127] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity across the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 10.5 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0128] (2) The diameter of the cylindrical gate is 10.5m. ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.56m (dead water level 571m), the highest point is 571.66m, and the lowest point is 571.38m (maximum water surface elevation difference 0.28m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.44m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom plate of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward flow velocity of 1.51 m / s and a maximum reverse flow velocity of -0.08 m / s. The reverse flow velocity range is within 0.56 m of the bottom plate, accounting for approximately 14.36% of the orifice height, with a velocity non-uniformity coefficient of 2.18~2.36. The head loss coefficient of the 10.5 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.36.

[0129] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity across the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 10.5 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0130] (3) The diameter of the cylindrical gate is 11m ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.57m (dead water level 571m), the highest point is 571.68m, and the lowest point is 571.32m (maximum water surface elevation difference 0.36m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.47m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward velocity of 1.49 m / s and a maximum reverse velocity of -0.07 m / s. The reverse velocity range is within 0.47 m of the bottom plate, accounting for approximately 12.1% of the orifice height, with a velocity non-uniformity coefficient of 2.16~2.33. The head loss coefficient of the 11 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.36.

[0131] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity across the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 11 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0132] (4) The diameter of the cylindrical gate is 11.5m. ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.57m (dead water level 571m), the highest point is 571.68m, and the lowest point is 571.31m (maximum water surface elevation difference 0.36m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.49m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward flow velocity of 1.49 m / s and a maximum reverse flow velocity of -0.05 m / s. The reverse flow velocity range is within 0.37 m of the bottom plate, accounting for approximately 9.48% of the orifice height, with a velocity non-uniformity coefficient of 2.12~2.28. The head loss coefficient of the 11.5 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.36.

[0133] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity at the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 11.5 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0134] (5) The diameter of the cylindrical gate is 12m ①Outflow condition Part of the water flow from the vertical diffusion section 4 flows into the closed well 2 from the center of the cover plate 9, and diffuses outward from the center of the closed well 2. The average water surface elevation inside the closed well 2 is 571.57m (dead water level 571m), the highest point is 571.69m, and the lowest point is 571.31m (maximum water surface elevation difference 0.38m). The water flow on the surface of the closed well 2 diffuses outward, with a maximum flow velocity of 1.52m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90°, and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The water surface in the reservoir area outside the inlet / outlet is relatively stable. The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom of the orifice. The average flow velocity across the trash rack cross-section is 0.64~0.69 m / s, with a maximum forward flow velocity of 1.42 m / s and a maximum reverse flow velocity of -0.02 m / s. The reverse flow velocity range is within 0.21 m of the bottom plate, accounting for approximately 5.38% of the orifice height, with a velocity non-uniformity coefficient of 2.06~2.22. The head loss coefficient of the 12 m diameter inlet / outlet of the cylindrical gate 1 from the beginning of the vertical diffuser section 4 to the reservoir area is 0.37.

[0135] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through various orifices, exhibiting good flow characteristics. Within the closed well 2, water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum velocity of 0.72 m / s. The water level within the closed well 2 is lower than that in the reservoir area (dead water level 571 m), with a highest water surface elevation of 570.83 m, a lowest water surface elevation of 570.72 m, and an average water surface elevation of 570.79 m, which is 0.21 m lower than the dead water level. The average flow velocity at the trash rack cross-section is 0.73~0.81 m / s, with a maximum velocity of 1.12 m / s and a velocity non-uniformity coefficient of 1.27~1.28. The head loss coefficient from the beginning of the vertical diffuser section 4 to the reservoir area at the 11.5 m diameter inlet / outlet of the cylindrical gate 1 is 0.15.

[0136] (6) Sensitivity analysis of the influence of cylindrical gate diameter on the hydraulic characteristics of inlet / outlet ①In the outflow condition, as the diameter of the cylindrical gate 1 increases, the average water surface elevation inside the closed well 2 increases, and the water surface height difference increases; as the diameter of the cylindrical gate 1 increases, the velocity non-uniformity coefficient of the trash rack cross section increases, and the range of the reverse velocity zone increases; as the diameter of the cylindrical gate 1 increases, the head loss coefficient increases.

[0137] ②In the inflow condition, the diameter of the cylindrical gate 1 increases, while the hydraulic indicators of the vertical shaft inlet / outlet are basically the same.

[0138] In summary, under outflow conditions, the larger the diameter of the cylindrical gate 1 at the vertical shaft inlet / outlet, the more water flows into the closed shaft 2, the higher the flow velocity within the closed shaft 2, the greater the change in water surface elevation, and the more complex the flow pattern. Simultaneously, the cover plate 9 has less obstruction to the vertical flow from the diffuser section 4, allowing the water to diffuse outwards from the center of the closed shaft 2 and then backflow on the vertical surface, ensuring sufficient diffusion of the flow at the orifice. This results in a more uniform velocity distribution across the trash rack cross-section, with a reduced velocity at the top and a smaller reverse velocity zone at the bottom; the head loss remains essentially the same. Under inflow conditions, the diameter of the cylindrical gate 1 has no impact on the hydraulic parameters of the inlet / outlet and does not generate harmful suction vortices. Comparing the hydraulic parameters of inlets / outlets with diameters of 10m, 10.5m, 11m, 11.5m, and 12m for the cylindrical gate 1, the head loss coefficient, the reverse velocity range of the trash rack cross-section, and the velocity non-uniformity coefficient are all at the same level under outflow conditions.

[0139] To further investigate the hydraulic characteristics of the vertical shaft inlet / outlet of the cylindrical gate 1, this embodiment uses a cylindrical gate 1 with a diameter of 10.5m as the base shape, and adds an 80cm wide bottom sill for the cylindrical gate 1, the extension part of the guide rail pier wall of the cylindrical gate 1, the straight pipe section 5 and the bend section 6 of the vertical shaft, and performs overall calculations. The study investigates the internal flow regime, flow distribution, velocity distribution across the trash rack section, and head loss of the vertical shaft inlet / outlet of the cylindrical gate 1 under dual-machine pumping (outflow) and dual-machine power generation (inflow) operating conditions.

[0140] Figure 12 This is a diagram of the vertical shaft inlet / outlet of a cylindrical gate. It should be noted that the outflow unevenness of the vertical shaft inlet / outlet (straight pipe section 5, length 16.91m, bend section 6, turning radius 15m) is -17.6% to 15.0%, and the outflow distribution does not meet the specifications. Therefore, this embodiment first optimized the design of the vertical shaft inlet / outlet. Straight pipe section 5 is now 19.91m long, and bend section 6 has a turning radius of 12m. The hydraulic indicators of this vertical shaft inlet / outlet all meet the specifications (flow unevenness less than 10%).

[0141] Based on the optimized vertical shaft inlet / outlet, and considering the influence of boundary conditions according to the arrangement of the cylindrical gate 1 inlet / outlet, the calculation area is determined. The calculation area includes: part of the reservoir area, cylindrical gate 1, all orifices, diffuser section 4, straight pipe section 5, bend section 6, and water diversion tunnel section. A 300m annular water area surrounding the inlet / outlet is taken as the reservoir boundary, and the tunnel section 200m downstream of the end of the transition section of bend section 6 is taken as the tunnel boundary.

[0142] To further investigate the hydraulic characteristics of the vertical shaft inlet / outlet of the cylindrical gate 1, this embodiment uses a cylindrical gate 1 with a diameter of 10.5m as the base shape, and adds an 80cm wide bottom sill for the cylindrical gate 1, the extension part of the guide rail pier wall of the cylindrical gate 1, the straight pipe section 5 and the bend section 6 of the vertical shaft, and performs overall calculations. The study investigates the internal flow regime, flow distribution, velocity distribution across the trash rack section, and head loss of the vertical shaft inlet / outlet of the cylindrical gate 1 under dual-machine pumping (outflow) and dual-machine power generation (inflow) operating conditions.

[0143] (1) Hydraulic characteristics of the vertical shaft inlet / outlet of the cylindrical gate 1 (dead water level) ①Outflow condition The water flow enters the bend section 6 from the water conveyance tunnel. After passing the bend, the main flow deviates to the outside of the bend and gradually becomes uniform after being adjusted by the straight section 5. After the water flow passes through the vertical diffusion section 4, part of the water flow flows into the closed well 2 from the center of the cover plate 9 and diffuses outwards from the center of the closed well 2. The average water surface elevation in the closed well 2 is 571.43m (dead water level 571m), the highest point is 571.54m, the lowest point is 571.27m, the maximum water surface elevation difference is 0.27m, and the maximum surface velocity of the water flow in the closed well 2 is 1.26m / s. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90° and flows out evenly after being diverted by the diversion pier 3. The velocity distribution between each orifice is relatively uniform. The main flow of the trash rack section is close to the middle and upper part of the orifice, and there is a reverse velocity at the bottom plate of the orifice. The water surface in the reservoir area outside the inlet / outlet is relatively stable.

[0144] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet of the cylindrical gate 1 is -8.50%~8.90%.

[0145] The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom plate of the orifice. The average flow velocity of the trash rack cross-section is 0.64~0.69 m / s, the maximum forward flow velocity is 1.53 m / s, and the maximum reverse flow velocity is -0.08 m / s. The reverse flow velocity range is within 0.57 m from the bottom plate, accounting for about 14.62% of the orifice height. The flow velocity non-uniformity coefficient is 2.18~2.39.

[0146] The head loss coefficient of the cylindrical gate 1 vertical shaft inlet / outlet is 0.58.

[0147] ②Inflow condition The water flow mainly originates from the reservoir area and enters the inlet / outlet relatively evenly and smoothly through the orifices, exhibiting good flow characteristics. Within the sealed well shaft 2, the water flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum flow velocity of 0.72 m / s. The water level within the sealed well shaft 2 is slightly lower than the reservoir area (dead water level 571 m), with the highest water surface elevation at 570.92 m, the lowest at 570.76 m, and an average at 570.84 m, which is 0.16 m lower than the dead water level. No vortices are generated near the inlet / outlet.

[0148] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet of the cylindrical gate 1 is -0.30%~0.30%.

[0149] The average flow velocity of the trash rack cross section is 0.73~0.81m / s, the maximum flow velocity is 1.12m / s, and the flow velocity non-uniformity coefficient is 1.27~1.28.

[0150] The head loss coefficient of the cylindrical gate 1 vertical shaft inlet / outlet is 0.41.

[0151] (2) Hydraulic characteristics of the vertical shaft inlet / outlet of the cylindrical gate 1 (normal water level) ①Outflow condition The water flow enters the bend section 6 from the water conveyance tunnel. After passing the bend, the main flow deviates to the outside of the bend and gradually becomes uniform after being adjusted by the straight section 5. After the water flow passes through the vertical diffusion section 4, part of the water flow flows into the closed well 2 from the center of the cover plate 9 and diffuses outwards from the center of the closed well 2. The average water surface elevation in the closed well 2 is 606.45m (normal water level is 606m), the highest point is 606.47m, the lowest point is 606.43m, and the maximum water surface elevation difference is 0.04m. The maximum flow velocity of the water flowing outwards from the closed well 2 is 0.08m / s, and the water surface is basically calm. The other part of the water flow, constrained by the cover plate 9, changes from vertical diffusion to horizontal diffusion by 90° and flows out evenly after being diverted by the diversion pier 3. The flow velocity distribution between each orifice is relatively uniform. The main flow of the trash rack section is close to the middle and upper part of the orifice, and there is a reverse flow velocity at the bottom plate of the orifice. The water surface in the reservoir area outside the inlet / outlet is relatively stable.

[0152] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet of the cylindrical gate 1 is -8.40%~8.70%.

[0153] The main flow velocity of the trash rack cross-section is located near the upper middle part of the orifice. There is a reverse flow velocity at the bottom plate of the orifice. The average flow velocity of the trash rack cross-section is 0.64~0.69m / s, the maximum forward flow velocity is 1.52m / s, and the maximum reverse flow velocity is -0.07m / s. The reverse flow velocity range is within 0.56m from the bottom plate, accounting for about 14.36% of the orifice height. The flow velocity non-uniformity coefficient is 2.20~2.38.

[0154] The head loss coefficient of the cylindrical gate 1 vertical shaft inlet / outlet is 0.58.

[0155] ②Inflow condition The water flow mainly enters the inlet / outlet from the reservoir area through the orifices in a relatively uniform and smooth manner, with a good flow pattern; the water flow in the closed well 2 flows around the edge of the cover plate 9 into the inlet / outlet, with a maximum flow velocity of 0.72 m / s; the water level in the closed well 2 is slightly lower than that of the reservoir area (normal water level 606 m), with the highest water surface elevation of 605.87 m, the lowest water surface elevation of 605.85 m, and the average water surface elevation of 605.86 m, which is 0.14 m lower than the normal water level.

[0156] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet of the cylindrical gate 1 is -0.20%~0.20%.

[0157] The average flow velocity of the trash rack cross section is 0.73~0.81m / s, the maximum flow velocity is 1.12m / s, and the flow velocity non-uniformity coefficient is 1.27~1.28.

[0158] The head loss coefficient of the cylindrical gate 1 vertical shaft inlet / outlet is 0.41.

[0159] (3) Hydraulic characteristics of conventional vertical shaft inlet / outlet ①Outflow condition The water flow enters the bend section 6 from the water conveyance tunnel. After passing the bend, the main flow deviates to the outside of the bend and gradually becomes uniform after being adjusted by the straight section 5. After being diffused by the vertical diffuser section 4, the water flow impacts the guide cone at the center of the cover plate 9. Then, under the diversion effect of the guide cone, the vertical diffusion changes to 90° and becomes horizontal diffusion. After being diverted by the diversion pier 3, it flows out evenly. The main flow of the trash rack section is close to the middle and upper part of the orifice. There is a reverse flow velocity at the bottom plate of the orifice, and the water surface in the reservoir area outside the inlet / outlet is relatively stable.

[0160] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet is -7.10% to 8.80%.

[0161] The mainstream flow in the trash rack cross-section is located near the upper middle part of the orifice, and there is a reverse flow velocity at the bottom plate of the orifice. The average flow velocity in the trash rack cross-section is 0.62~0.69 m / s. The mainstream flow is located near the upper middle part of the orifice, and there is a reverse flow velocity near the bottom plate. The maximum forward flow velocity is 1.56 m / s, and the maximum reverse flow velocity is -0.12 m / s. The reverse flow velocity range is within 0.84 m from the bottom plate, accounting for about 21.5% of the orifice height, and the velocity non-uniformity coefficient is 2.28~2.57.

[0162] The head loss coefficient of the vertical shaft inlet / outlet is 0.57.

[0163] ②Inflow condition The water mainly flows from the reservoir area into the inlet / outlet in a relatively uniform and smooth manner through the various orifices, resulting in a good flow pattern.

[0164] The flow rate unevenness of each orifice of the vertical shaft inlet / outlet is -0.13% to 0.30%.

[0165] The average flow velocity of the trash rack cross section is 0.73~0.81m / s, the maximum flow velocity is 1.12m / s, and the flow velocity non-uniformity coefficient is 1.27~1.28.

[0166] The head loss coefficient of the vertical shaft inlet / outlet is 0.41.

[0167] In summary, comparing the hydraulic characteristics of the cylindrical gate 1 vertical shaft inlet / outlet and the conventional vertical shaft inlet / outlet, under outflow conditions, the degree of flow unevenness and head loss at each orifice are basically the same for both types of inlet / outlet. However, the cylindrical gate 1 vertical shaft inlet / outlet can improve the velocity distribution across the trash rack cross-section, reduce the velocity unevenness coefficient, and decrease the reverse velocity range at the bottom of the trash rack cross-section. Under inflow conditions, the flow distribution, velocity unevenness coefficient, and head loss are basically the same for both types of inlet / outlet.

[0168] Table 3. Comparison of various hydraulic indicators (dead water level 571m)

[0169] During pumping operation (outflow), water flows from tunnel section 7 into the reservoir. The inflow velocity at the tunnel boundary is given according to the flow rate; the water level at the reservoir boundary is set according to the hydrostatic pressure; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free surface.

[0170] During power generation (inflow), the water flows from the reservoir to tunnel section 7. At the reservoir boundary, the water level is set based on the static pressure; at the tunnel boundary, the outflow velocity is given based on the flow rate; the solid wall boundary adopts a no-slip condition; the reservoir liquid surface is a free surface.

[0171] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A vertical shaft-type inlet and outlet gate system for a pumped storage power station, characterized in that, The cylindrical gate shaft inlet and outlet are arranged sequentially along the power generation water flow direction, consisting of a closed shaft, a trash rack section, a diffuser section, a straight pipe section, a bend section, and a tunnel section; during construction, the cylindrical gate is installed at the top of the closed shaft. The lower end of the trash rack section is the diffuser section, and the top of the diffuser section is a funnel shape. The boundary curve of the diffuser section is a 1 / 4 elliptical curve, through which the funnel shape gradually transforms into a circular vertical shaft pipe. The trash rack section is equipped with a cover plate, a diversion pier, and a trash rack. The trash rack has orifices that serve as inlet and outlet orifices. The lower part of the cover plate of the trash rack section is connected to the diversion pier. A hole is excavated in the center of the cover plate. The diameter of the hole in the center of the cover plate is the same as that of the cylindrical gate. A groove is set in the diffuser section, which is a ring structure. A water-stop sealing structure is arranged around the groove. When the cylindrical gate is closed, the bottom of the cylindrical gate coincides with the bottom of the groove. At this time, the water in the vertical shaft and the water in the reservoir do not flow between them. The cylindrical gate is arranged above the inlet and outlet, and the cylindrical gate is connected vertically. The bottom of the cylindrical gate is fixed to the inner surface of the concrete of the diffuser section, and the top of the cylindrical gate is fixed to the cover plate of the trash rack section.

2. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, The diameter of the hole in the cover plate is greater than 2 / 3 of the outer diameter of the cover plate.

3. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, The diversion pier is flush with the inner wall of the sealed well.

4. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, The cover plate has a planar shape that is an inscribed regular polygon of a circle.

5. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, Set up 8-12 diversion piers.

6. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, The card slot width is not less than 0.5m.

7. The pumped storage power station shaft-type inlet and outlet gate system according to claim 1, characterized in that, It has a straight pipe section of not less than 5m.

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