Asymmetric double-layer narrow slit type swirling flow starting structure suitable for swirling flow vertical shaft spillway tunnel

Abstract

The asymmetric double-layer narrow slit type rotation starting structure suitable for the rotational flow vertical shaft spillway tunnel comprises a first connecting section which is connected to the tail end of an upper flat section of the rotational flow vertical shaft spillway tunnel and comprises a first part, a second part and a connecting part used for connecting the first part and the second part, and the first connecting section and the second connecting section are connected with each other by taking the horizontal direction as a benchmark. The second part is higher than the first part; the second connecting section is connected to the tail end of the first part in the first direction, and the first direction is configured to be the direction from the upper flat section to a volute chamber of the rotational flow vertical shaft spillway tunnel; and the third connecting section is connected to the tail end of the second part along the first direction. Through the arrangement, the problems that small and medium flow is difficult to form wall-attached rotational flow in the volute chamber or water flow swirling is not smooth and the like can be solved, and the purpose of improving the energy dissipation effect is achieved. In the large-flow stage, water flow passes through the first part and the second part at the same time and forms confluence when passing through the second connecting section and the third connecting section, the inflow kinetic energy and the tangential speed are enhanced, and the swirling efficiency and the swirling stability are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of flood discharge and energy dissipation technology in water conservancy and hydropower projects, and in particular to an asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft flood discharge tunnels. Background Technology

[0002] Spillway tunnels are an important component of hydropower station projects, bearing the heavy responsibility of discharging excess floodwater during the flood season. Vertical shaft vortex spillway tunnels are a commonly used layout in many projects, offering advantages such as simple layout, high head, large flow rate, strong adaptability, and high energy dissipation rate. Vertical shaft vortex spillway tunnels converted from diversion tunnels also possess certain economic advantages. Vertical shaft spillway tunnels mainly include vortex-induced vortex type and forced vortex type. Forced vortex type vertical shaft vortex spillway tunnels mainly consist of an inlet control section, upper horizontal section, vortex chamber section, vertical shaft section, energy dissipation well section, slope section, and lower horizontal section.

[0003] Forced-swirl vertical shaft spillways are commonly used for flood discharge and energy dissipation in the lower reservoirs of pumped-storage hydropower stations and may serve as regular spillways. They are also used in flood drainage systems in mountainous cities, resulting in high operational frequency and thus placing higher demands on the safety of the project. Furthermore, this type of vertical shaft spillway is characterized by its adaptability to large head variations, high flow rates, and frequent operation. The flow connection between the upper horizontal section of the shaft and the vortex chamber is particularly important, having a decisive impact on the flow pattern within the vortex chamber and the shaft. A large connection angle will cause the incident water flow to impact the shaft wall, forming a reflected flow. A large amount of water will cascade into the bottom energy dissipation well, leaving relatively little swirling flow along the wall, resulting in poor energy dissipation. Summary of the Invention

[0004] In view of this, this application provides an asymmetric double-layer narrow-slot vortex initiation structure suitable for vortex vertical shaft spillways, which can achieve the purpose of zoned outflow. Small and medium flow rates exit through the bottom narrow slot, while large floods exit through a combination of bottom and surface narrow slots. This arrangement can avoid the problems of difficulty in forming wall-adhering vortices or unsmooth vortex initiation in the vortex chamber for small and medium flow rates, thereby improving the energy dissipation effect.

[0005] To achieve the above objectives, this application provides the following technical solution: An asymmetric double-layer narrow-slot vortex initiation structure suitable for vortex vertical shaft spillway tunnels includes: The first connecting section is connected to the end of the upper horizontal section of the vortex vertical shaft flood discharge tunnel, and includes a first part, a second part, and a connecting part for connecting the first part and the second part. With the horizontal direction as a reference, the second part is higher than the first part. The second connecting section is connected to the end of the first part along a first direction, the first direction being configured as the direction from the upper flat section to the vortex chamber of the vortex shaft spillway. The third connecting segment is connected to the end of the second part along the first direction; In the first case, the water flows through the first part and the second connecting section under its own weight and enters the vortex chamber. In the second case, the water flows into the vortex chamber through the second connecting section and the third connecting section under its own weight and merges with the first part and the second part.

[0006] Optionally, in the above-mentioned asymmetric double-layer narrow-slot vortex initiation structure applicable to the vortex vertical shaft flood discharge tunnel, along the first direction, the asymmetric double-layer narrow-slot vortex initiation structure includes a first sidewall and a second sidewall arranged opposite to each other. One end of the first sidewall is connected to the upper flat section and the other end is connected to the vortex chamber. One end of the second sidewall is connected to the upper flat section and the other end is connected to the vortex chamber. The first sidewall extends along the first direction, and the second sidewall is inclined toward the position of the first sidewall, so that the first sidewall and the second sidewall enclose a tapering opening connected to the vortex chamber. The first sidewall is disposed adjacent to the first portion, and the second sidewall is disposed adjacent to the second portion.

[0007] Optionally, in the above-described asymmetric double-layer narrow-slit vortex initiation structure applicable to vortex vertical shaft spillway tunnels, the slope ratio of the first part is greater than the slope ratio of the upper flat section, and the slope ratio of the upper flat section is equal to the slope ratio of the second part.

[0008] Optionally, in the above-described asymmetric double-layer narrow-slit vortex initiation structure applicable to vortex vertical shaft spillway tunnels, the second connecting section includes a curved section connected to the end of the first part and an entry section connected to the curved section.

[0009] Optionally, in the above-mentioned asymmetric double-layer narrow-slit vortex initiation structure applicable to vortex vertical shaft flood discharge tunnels, the slope ratio of the upper flat section ranges from 1:30 to 1:20; the slope ratio of the first part ranges from 1:6 to 1:8; the slope ratio of the third connecting section ranges from 1:5 to 1:10; and the slope ratio of the entry section ranges from 0 to 1:10.

[0010] Optionally, in the above-described asymmetric double-layer narrow-slit vortex initiation structure applicable to vortex vertical shaft spillway tunnels, the connecting portion is a curved surface or an inclined surface.

[0011] Optionally, in the above-described asymmetric double-layer narrow-slit vortex initiation structure applicable to vortex vertical shaft spillway tunnels, in the first case, the angle between the inner streamline of the second connecting section and the tangent at the vortex chamber incident point is... a 1; among which, ∠ɑ1 = 90° - ∠ɑ2 ∠ɑ2=atan((R1-B2) / CD) B2=β2B0 CD = SQRT(R1) 2 -(R1-B2) 2 ) In the formula: R1 is the radius of the vortex chamber; B2 is the width of the second connecting segment; β2 is the ratio of the width of the second connecting segment to the width of the upper flat segment; B0 is the width of the upper horizontal segment.

[0012] α2 is the first intermediate parameter for calculating the included angle α1; CD is the second intermediate parameter for calculating the included angle α1.

[0013] This application provides an asymmetric double-layer narrow-slot vortex initiation structure suitable for vortex vertical shaft spillways. By incorporating an asymmetric double-layer connecting section structure, it achieves flexible and efficient guidance of water flow into the vortex chamber under different inflow conditions. At low to medium flow rates, the water flow is guided to the first section via the guide section and smoothly enters the vortex chamber through the second connecting section. This design avoids problems such as difficulty in forming wall-adhering vortices or unsmooth vortex initiation at low to medium flow rates, thus improving energy dissipation. It should be noted that a vertical guide plate is installed within the vortex chamber to guide the water flow to rotate in a specific direction, forming controllable vortex motion. During high flow rates or full-load operation, the water flow simultaneously passes through the first and second sections and merges with the third connecting section, enhancing the inflow kinetic energy and tangential velocity, significantly improving vortex initiation efficiency and vortex stability. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0015] Figure 1 A schematic diagram of the three-dimensional structure of the asymmetric double-layer narrow-slit spinning structure provided in this application; Figure 2 A schematic diagram of the asymmetric double-layer narrow-slit spinning structure provided in this application; Figure 3 Provided for this application Figure 2 A schematic diagram of the local structure; Figure 4 An enlarged view of the vortex chamber provided in this application.

[0016] 1. First connecting section; 2. Second connecting section; 3. Third connecting section; 4. Vortex chamber; 11. First part; 12. Second part; 13. Connecting part; 5. First sidewall; 6. Second sidewall; 7. Vertical guide vane. Detailed Implementation

[0017] This application provides an asymmetric double-layer narrow-slot vortex initiation structure suitable for vortex vertical shaft spillways, which can achieve the purpose of zoned outflow. Small and medium flow rates exit through the bottom narrow slot, while large floods exit through a combination of bottom and surface narrow slots. This arrangement can avoid the problems of difficulty in forming wall-adhering vortices or unsmooth vortex initiation in the vortex chamber for small and medium flow rates, thereby improving the energy dissipation effect.

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] In the existing technology, the angle between the inner streamline at the end of the upper horizontal section and the tangent of the vortex chamber 4 at the incident point is... a 3. The transverse thickness of the water layer is mainly affected by the contraction ratio at the end of the upper horizontal section. It should be noted that the transverse thickness of the water layer refers to the concentrated width or distribution range of the mainstream water tongue in the horizontal direction (transverse) when the water flows into the vortex chamber 4 or impacts the vertical shaft wall.

[0020] The greater the transverse thickness of the water tank, the greater the contraction ratio, and the greater the maximum angle of entry, the more difficult it is to form a smooth, wall-attached vortex within vortex chamber 4. Among these factors, ∠ɑ3 = 90° - ∠ɑ4 ∠ɑ4 = ∠ɑ6 + ∠ɑ5 ∠ɑ6=atan( i 1)=atan((1-β1)B0 / L) ∠ɑ5=atan((R1-B1) / AB) B1=β1B0 AB = SQRT(R1) 2 -(R1-B1) 2 ) In the formula: α3 is the angle at which the upper horizontal section outflow and the vortex chamber 4 avoid confluence in the existing technology; R1 is the radius of the vortex chamber 4; B2 is the width of the upper flat section after the plane is contracted in the prior art; β1 is the ratio of the width of the upper flat section after the plane is contracted to the width of the upper flat section in the prior art; B0 is the width of the upper horizontal segment; i 1 represents the lateral contraction angle of the upper horizontal segment in the prior art; α4 is the first intermediate parameter for calculating the included angle α3; α6 is the second intermediate parameter for calculating the included angle α3; AB is the third intermediate parameter for calculating the included angle α3; B1 is the fourth intermediate parameter for calculating the included angle α3; α5 is the fifth intermediate parameter for calculating the included angle α3.

[0021] The above calculation formula shows that in order to reduce ∠ɑ3, the lateral contraction angle needs to be increased. i 1. To reduce the contraction ratio β1, after the contraction ratio is reduced to a certain extent, the water flow in the contraction section will be locally backed up or even a hydraulic jump will occur in the contraction section. Therefore, this invention considers designing the contraction section as an asymmetric double-layer narrow slit.

[0022] Based on this, such as Figures 1-4 As shown, this application provides an asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex shaft spillway tunnels. The structure includes a first connecting section 1, connected to the end of the upper horizontal section of the vortex shaft spillway tunnel, and includes a first part 11, a second part 12, and a connecting part 13 for connecting the first part 11 and the second part 12. With the horizontal direction as a reference, the second part 12 is higher than the first part 11. A second connecting section 2 is connected to the end of the first part 11 along a first direction, configured as the direction from the upper horizontal section to the vortex chamber 4 of the vortex shaft spillway tunnel. A third connecting section 3 is connected to the end of the second part 12 along the first direction. In a first case, water flows through the first part 11 and the second connecting section 2 under its own weight and enters the vortex chamber 4. In a second case, water flows through the first part 11 and the second part 12 in a merged state under its own weight and enters the vortex chamber 4.

[0023] It should be noted that the first case refers to the case where the flood flow is small to medium, and the second case refers to the case where the flood flow is large. The flow rate is mainly determined by the size of the asymmetric double-layer connecting section structure.

[0024] By setting an asymmetrical double-layer connecting section structure, the water flow can be flexibly and efficiently guided into the vortex chamber 4 under different inflow conditions. At low to medium flow rates, the water flow is guided to the first section 11 by the guide section and smoothly enters the vortex chamber 4 through the second connecting section 2. This design avoids problems such as difficulty in forming a wall-adhering vortex or uneven vortex initiation at low to medium flow rates, thus improving energy dissipation. It should be noted that a vertical guide plate 7 is installed inside the vortex chamber 4 to guide the water flow to rotate in a specific direction, forming a controllable vortex motion. During high flow rates or full-load operation, the water flow simultaneously passes through the first section 11 and the second section 12, and merges with the third connecting section 3 via the second connecting section 2, enhancing the inflow kinetic energy and tangential velocity, significantly improving vortex initiation efficiency and vortex stability.

[0025] This structure, through its staggered double-layer layout, optimizes the water flow transition and energy conversion process, thereby improving the overall discharge capacity and operational safety of the spillway.

[0026] It should be noted that the first part 11 and the second connecting section 2 constitute the bottom narrow slit, and the part above the bottom narrow slit constitutes the surface narrow slit. When the water flow is small, the water flows in the bottom narrow slit and flows in the vortex chamber 4 in a wall-hugging swirling manner under the guidance of the vertical guide plate. When the water flow is large, the water flow converges in the bottom narrow slit and the surface narrow slit and flows in the vortex chamber 4 in a wall-hugging swirling manner under the guidance of the vertical guide plate.

[0027] It should also be noted that "narrow slit" is a shorthand for a contracting flow channel, where the channel narrows from wide to narrow along the flow direction, exhibiting lateral contraction. Its main purpose is to adjust the flat flow pattern into a narrow and deep one, causing the water flow to rise longitudinally. In this application, its more specific function is to reduce the thickness of the lateral water layer and decrease the counter-current angle at vortex chamber 4, thereby creating a complete swirling flow pattern within vortex chamber 4.

[0028] Furthermore, along the first direction, the asymmetric double-layer narrow-slit vortex initiation structure includes a first sidewall 5 and a second sidewall 6 arranged opposite to each other. One end of the first sidewall 5 is connected to the upper flat section, and the other end is connected to the vortex chamber 4. One end of the second sidewall 6 is connected to the upper flat section, and the other end is connected to the vortex chamber 4. The first sidewall 5 extends along the first direction, and the second sidewall 6 is inclined towards the position of the first sidewall 5, so that the first sidewall 5 and the second sidewall 6 enclose a gradually narrowing opening connected to the vortex chamber 4. The first sidewall 5 is adjacent to the first part 11, and the second sidewall 6 is adjacent to the second part 12. It can be understood that the asymmetric double-layer narrow-slit vortex initiation structure narrows from wide to narrow along the first direction. Traditional straight-entry structures often cause water to "directly impact" or "obliquely impact" the wall due to excessively large included angles, resulting in impact, splashing, and energy dissipation. This structure, through the guiding effect of the tapering opening, ensures that the water flow has a pre-swirling tendency aligned with the vortex direction before entering the vortex chamber 4. Furthermore, the vertical guide plate 7 installed inside the vortex chamber 4 is aligned with the water flow's entry direction, significantly reducing the included angle and achieving a low-angle, wall-hugging, smooth entry. This minimizes the incident angle between the incoming water flow and the wall of the vortex chamber 4, causing the water flow to generate a wall-hugging swirling flow within the vortex chamber 4. This effectively prevents the water flow from impacting the vortex chamber 4 wall at a large incident angle, thus avoiding a cascading flow and reducing the pulsating pressure at the bottom of the energy dissipation well.

[0029] It should be noted that the incident angle refers to the angle between the main flow direction of the water entering the vortex chamber 4 and the tangent direction of the local wall of the vortex chamber 4.

[0030] In an optional embodiment, the slope ratio of the first section 11 is greater than that of the upper flat section, and the slope ratio of the upper flat section is equal to that of the second section 12. The greater slope ratio of the first section 11 makes the first section 11 more inclined than the upper flat section. The more inclined slope allows the water flow entering the first section 11 to obtain a higher flow velocity and stronger kinetic energy. Especially under low flow or non-full flow conditions, this structure ensures that the water flow travels close to the bottom and obtains a favorable inflow angle and tangential momentum when entering the vortex chamber 4, thereby spiraling downwards close to the side wall of the vortex chamber 4 and promoting the rapid formation of a stable vortex.

[0031] In an optional embodiment, the second connecting section 2 includes a curved section connected to the end of the first part 11 and an inlet section connected to the curved section. It should be noted that the inlet section is connected to the vortex chamber 4. The curved section helps to gradually adjust the water flow flowing down the first part 11 to an inflow direction closer to the wall of the vortex chamber 4, creating conditions for it to form a favorable tangential velocity component when entering the vortex chamber 4.

[0032] The slope ratio of the upper section ranges from 1:30 to 1:20; the slope ratio of the first part 11 ranges from 1:6 to 1:8; the slope ratio of the third connecting section 3 ranges from 1:5 to 1:10; and the slope ratio of the entry section ranges from 0 to 1:10.

[0033] In an optional embodiment, the connecting portion 13 is a curved or inclined surface, which facilitates a smooth transition of water flow.

[0034] In the first case, the angle between the streamline on the inner side of the second connecting section 2 and the tangent at the incident point of the vortex chamber 4 is α1; where, ∠ɑ1 = 90° - ∠ɑ2 ∠ɑ2=atan((R1-B2) / CD) B2=β2B0 CD = SQRT(R1) 2 -(R1-B2) 2 ) In the formula: R1 is the radius of the vortex chamber 4; B2 is the width of the second connecting segment; β2 is the ratio of the width of the second connecting segment to the width of the upper flat segment; B0 is the width of the upper horizontal segment; α2 is the first intermediate parameter for calculating the included angle α1; CD is the second intermediate parameter for calculating the included angle α2.

[0035] The above calculation formula shows that the smaller the shrinkage ratio β2, the smaller the angle of convergence ∠ɑ1. Based on relevant engineering experience, it is recommended that the shrinkage ratio β2 be in the range of 0.15~0.2.

[0036] Application example.

[0037] A proposed pumped-storage hydropower station is converting its left bank spillway from a diversion tunnel into a vertical shaft vortex spillway. The upstream inlet uses a practical weir, with an upper horizontal section slope of 1:25. Before entering vortex chamber 4 in the vertical shaft, the upper horizontal section slopes to 1:10, with a circular arc connecting the two sections. The upper horizontal section is 8.00m wide, gradually narrowing at a 1:16 ratio along the left sidewall from chainage 0+079.238m to a width of 4.0m at the inlet of vortex chamber 4, with a narrowing ratio β1 of 0.5. Vortex chamber 4 has a diameter of 13.0m, and the vertical shaft has a diameter of 9.0m. During operation, the spillway will discharge water from a partial gate opening of 2.0m to the check flood level, with a flow range of 96m³ / h. 3 / s~594m 3 / s, if at 594m 3 If the control flow rate is / s, then the contraction ratio at the outlet of the upper level section needs to be controlled at 0.5. Under this contraction ratio condition, the maximum counter-attack angle ∠ɑ3 is 64°, and the flow rate is 96m³ / s. 3 / s~300m 3 When the flow rate is in the range of / s, the water flow is prone to impacting the wall of the vortex chamber 4, forming a drop flow pattern, which in turn affects the energy dissipation effect of the energy dissipation well and increases the pulsating pressure of the bottom plate.

[0038] To avoid the above-mentioned adverse factors, the outlet of the upper horizontal section was adjusted to an asymmetric double-layer narrow-slot vortex initiation structure. The contraction ratio β2 of the bottom narrow slot is 0.15 (1.2m), while the contraction ratio β1 of the surface narrow slot is 0.4 (3.2m). The optimized maximum countercurrent angle ∠ɑ3 is 54°. The optimized double-layer narrow slot ensures that the cross-sectional area of ​​the narrow slot outlet is comparable to that before optimization, ensuring that the narrowed slot does not affect the flow capacity. Through shape optimization, it can better avoid the formation of a large countercurrent drop in the inflow within vortex chamber 4. Especially at a low flow rate of 96m³ / h. 3 / s~300m 3 At a flow rate of / s, the flow rate is discharged from the bottom vertical slit, and its maximum counter-current angle ∠ɑ1 is 35°, which can ensure that a good wall-attached swirling flow pattern is formed in the vortex chamber 4 under the condition of normal discharge flow rate.

[0039] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0040] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0041] It should also be noted that in the apparatus, equipment, and housing of this application, the components or steps can be disassembled and / or reassembled. These disassemblies and / or reassemblies should be considered as equivalent solutions of this application.

[0042] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0043] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0044] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An asymmetric double-layer narrow-slot vortex initiation structure suitable for vortex vertical shaft spillway tunnels, characterized in that, include: The first connecting section is connected to the end of the upper horizontal section of the vortex vertical shaft flood discharge tunnel, and includes a first part, a second part, and a connecting part for connecting the first part and the second part. With the horizontal direction as a reference, the second part is higher than the first part. The second connecting section is connected to the end of the first part along a first direction, the first direction being configured as the direction from the upper flat section to the vortex chamber of the vortex shaft spillway. The third connecting segment is connected to the end of the second part along the first direction; In the first case, the water flows through the first part and then through the second connecting section into the vortex chamber under its own weight. In the second case, the water flow merges with the first part and the second part under its own weight, and flows through the second connecting section and the third connecting section in a merged state before entering the vortex chamber.

2. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 1, characterized in that, Along the first direction, the asymmetric double-layer narrow slit vortex-inducing structure includes a first sidewall and a second sidewall disposed opposite to each other. One end of the first sidewall is connected to the upper flat section and the other end is connected to the vortex chamber. One end of the second sidewall is connected to the upper flat section and the other end is connected to the vortex chamber. The first sidewall extends along the first direction and the second sidewall is inclined toward the position of the first sidewall, so that the first sidewall and the second sidewall enclose a tapered opening connected to the vortex chamber. The first sidewall is disposed adjacent to the first portion, and the second sidewall is disposed adjacent to the second portion.

3. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 1, characterized in that, The slope ratio of the first part is greater than the slope ratio of the upper flat section, and the slope ratio of the upper flat section is equal to the slope ratio of the second part.

4. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 1, characterized in that, The second connecting segment includes a curved segment connected to the end of the first portion and an entry segment connected to the curved segment.

5. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 4, characterized in that, The slope ratio of the upper section ranges from 1:30 to 1:20; the slope ratio of the first part ranges from 1:6 to 1:8; the slope ratio of the third connecting section ranges from 1:5 to 1:10; and the slope ratio of the entry section ranges from 0 to 1:

10.

6. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 1, characterized in that, The connecting part is a curved surface or an inclined surface.

7. The asymmetric double-layer narrow-slit vortex initiation structure suitable for vortex vertical shaft spillway tunnels according to claim 1, characterized in that, In the first case, the angle between the inner streamline of the second connecting section and the tangent at the incident point of the vortex chamber is α1; wherein, ∠ɑ1 = 90° - ∠ɑ2 ∠ɑ2=atan((R1-B2) / CD) B2=β2B0 CD= SQRT(R1 2 -(R1-B2) 2 ) In the formula: R1 is the radius of the vortex chamber; B2 is the width of the second connecting segment; β2 is the ratio of the width of the second connecting segment to the width of the upper flat segment; B0 is the width of the upper horizontal segment; α2 is the first intermediate parameter for calculating the included angle α1; CD is the second intermediate parameter for calculating the included angle α1.

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