A convex nose ridge

Abstract

The present invention provides a convex flow-inspiring nose sill, which includes a first-level sill and a second-level sill, wherein the first-level sill is a transverse diffusion type sill, including a chute bottom plate expanding along the water flow direction and side walls on both sides; the second-level sill is a convex tooth sill without side walls; the present invention adopts a convex tooth sill without side walls directly connected to the outlet end of the transverse diffusion type sill, and the width of the convex tooth sill gradually shrinks along the direction of water flow, so that the high-speed water flow passing through the convex flow-inspiring nose sill cantilevers from different positions and different elevations, and the water tongue at the sill is fully diffused longitudinally and transversely, so that the actual water inlet width of the downstream water flow is wider than that of the conventional sill, reducing the actual water inlet single-width flow of the water tongue, and reducing the scouring effect of the incident water flow on the riverbed bottom plate and the bank.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy projects, and in particular relates to a convex flow nose sill. Background Art

[0002] Diversion energy dissipation refers to installing various types of diversion sills at the end of the spillway of a water discharge structure. This uses the enormous kinetic energy, or velocity, of the downstream water to divert the high-speed water into the air, where it then descends into the river channel away from the structure. As the water loses its solid boundary, it initially loses a small amount of kinetic energy due to turbulence and air resistance. However, the majority of this energy is dissipated when the water enters the downstream water body, collides with and mixes with the downstream water. Combined with the viscosity of the water, the kinetic energy is converted into heat energy and consumed under the effects of strong shear and turbulence. When the river valley is narrow, the bottom slope is steep, the discharge volume is large, and the downstream water cushion is shallow, the water transported by the existing diversion sills can severely scour the downstream riverbed and bank slopes. Therefore, it is urgent to design a diversion sill that can maximize the diffusion of the downstream water flow, reduce the downstream flow rate per unit width, and improve the energy dissipation rate to reduce the depth of the downstream scour pit and the amount of protective engineering work. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a convex flow nose sill to diffuse the downstream water flow from the upstream as much as possible, with the advantages of simple structure and sufficient vertical and horizontal diffusion of the water tongue out of the sill.

[0004] The present invention discloses a convex sill connected to the spillway, comprising a first-level sill and a second-level sill;

[0005] The first-level embankment includes a chute bottom plate that expands along the water flow direction and side walls on both sides;

[0006] The secondary embankment has no side wall, the width of the secondary embankment is smaller than the outlet width of the primary embankment, and the width of the secondary embankment gradually shrinks along the direction of water flow;

[0007] The first-level embankment is connected to the second-level embankment to form three-dimensional dispersion outlets with different elevations and plane positions, so as to realize the horizontal and vertical diffusion of the water tongue behind the embankment.

[0008] The convex flow-inspiring nose sill provided by the present invention adopts a convex tooth sill without side wall directly connected to the outlet end of the sill that diffuses laterally on the bottom plate of the chute. The width of the convex tooth sill gradually shrinks along the direction of the water flow, so that the high-speed water flow passing through the convex flow-inspiring nose sill cantilevers from different positions and different elevations. The water tongue at the outlet of the sill diffuses fully longitudinally and laterally, and the actual water inlet width of the downstream water flow is wider than that of the conventional sill, which reduces the actual water inlet single-width flow of the water tongue and alleviates the scouring effect of the incident water flow on the riverbed bottom plate and the bank.

[0009] Furthermore, the secondary sill is tangentially connected to the chute bottom plate to achieve a curved surface transition to ensure smooth water flow along the way, thereby reducing the cavitation erosion risk of the convex sill.

[0010] Furthermore, the distance B1 between the secondary sill and the left wall of the primary sill outlet and the distance B3 between the secondary sill and the right wall of the primary sill outlet are as follows: B1 B3; The left side contraction angle β1 of the secondary embankment has a value range of [5°, 10°], and / or the right side contraction angle β2 of the secondary embankment has a value range of [5°, 10°]. Depending on the terrain and geological conditions of the downstream river channel, the connection position between the secondary embankment and the primary embankment and the direction of the water tongue can be flexibly adjusted to the center or left; the left and center settings of the secondary embankment correspond to different shapes of the diverted water tongue, and the offset water tongue and the symmetrical water tongue have different energy dissipation effects; the connection position between the secondary embankment and the primary embankment, combined with the side contraction angle β of the secondary embankment, are used to control the water tongue landing point to adapt to the different geological conditions of the downstream river channel.

[0011] Furthermore, the distance B1 between the secondary embankment and the left wall of the primary embankment outlet and the distance B3 between the secondary embankment and the right wall of the primary embankment outlet are: B1>B3; the left contraction angle β1 of the secondary embankment has a value range of [5°, 10°], and / or the right contraction angle β2 of the secondary embankment has a value range of [5°, 10°]. According to the terrain and geological conditions of the downstream river channel, the connection position of the secondary embankment and the primary embankment and the direction of the water tongue can be flexibly adjusted to the right; the right setting of the secondary embankment corresponds to different diverting water tongue shapes, and the diverting water tongue and the symmetrical water tongue have different energy dissipation effects; the connection position of the secondary embankment and the primary embankment combined with the side contraction angle β of the secondary embankment are used to control the water tongue landing point to adapt to the different geological conditions of the downstream river channel.

[0012] Furthermore, the value range of the first-level cantilever angle θ is [-30°, 30°]; different types of first-level cantilever can be selected according to different engineering conditions, such as: reverse arc cantilever type, flat cantilever type and downward angle cantilever type. At the same time, in order to cooperate with the second-level cantilever to make the water tongue effectively cantilever and fully diffuse, the absolute value of the maximum cantilever angle does not exceed 30°.

[0013] Furthermore, the outlet width of the first level ridge is , where b is the width of the spillway before the overhang, L1 is the length of the first-level overhang, α1 is the diffusion angle of the left wall of the first-level overhang, and α2 is the diffusion angle of the right wall of the first-level overhang.

[0014] Furthermore, the diffusion angle α1 of the left wall of the first-level overhang is in the range of [0°, 7°]; and / or the diffusion angle α2 of the right wall of the first-level overhang is in the range of [0°, 7°]. The diffusion angle values ​​ensure that water does not impact the downstream slope after flowing out of the overhang.

[0015] Furthermore, the angle difference between the secondary pick and the primary pick is ,in, is the maximum downstream flow rate, and B is the outlet width of the first-level embankment.

[0016] Furthermore, the horizontal length of the secondary ridge .

[0017] Furthermore, the starting width of the secondary pick is .

[0018] Furthermore, the width of the second-stage pick end is .

[0019] The present invention has the following beneficial effects:

[0020] The convex flow nose sill provided by the present invention has a simple structure, low cavitation erosion risk, and sufficient longitudinal and transverse diffusion of the water tongue at the sill, which increases the downstream water body's ability to dissipate the brakes on high-speed downstream water flow, reduces the downstream scouring depth and hydraulic parameters, alleviates the difficulty of downstream energy dissipation and anti-scouring, ensures project safety, reduces downstream protection engineering volume, and saves project construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the cross-sectional structure of a convex flow-rising nose provided by some embodiments of the present invention,

[0022] Figure 2 Schematic diagram of the planar structural arrangement of a convex flow nose provided by some embodiments of the present invention;

[0023] Description of reference numerals:

[0024] 1 spillway, 2 spillway side wall, 3 first-level overhang, 3-1 chute bottom plate, 3-2 side wall, 4 second-level overhang, 5 downstream river channel, 6 downstream river channel scouring pit, 7 overhang water tongue, 8 water tongue drop area,

[0025] The width of the spillway before the overhang b; the angle difference between the second-level overhang and the first-level overhang △θ;

[0026] First-level overhang body parameters: First-level overhang side wall height h 导 Diffusion angle α1 of the left wall of the first-level overhang; Diffusion angle α2 of the right wall of the first-level overhang; Length L1 of the first-level overhang; Radius R1 of the anti-arc of the first-level overhang; Overhang angle θ of the first-level overhang; Water depth h1 in the vertical direction of the top of the first-level overhang; Width B of the outlet of the first-level overhang;

[0027] Secondary overhang parameters: distance from the secondary overhang to the left wall of the primary overhang exit (B1); width of the secondary overhang starting end (B2); distance from the secondary overhang to the right wall of the primary overhang exit (B3); width of the secondary overhang ending end (B4); length of the secondary overhang (L); contraction angle on the left side of the secondary overhang (β1); contraction angle on the right side of the secondary overhang (β2); and radius of the secondary overhang (R2).

[0028] The water head at the top of the first-stage embankment is H0; the water level difference between the upstream and downstream is H; the height difference between the top of the first-stage embankment and the downstream water surface is h2; the downstream water depth is h t ; Downstream scour depth T. DETAILED DESCRIPTION

[0029] In order to describe the technical solution of the present invention more clearly and completely, the present invention is further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention. Terms such as "inside", "outside", "upper", "lower", "top", and "bottom" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] The present invention provides a convex sill connected to a spillway 1, comprising a primary sill 3 and a secondary sill 4. The primary sill 3 comprises a chute bottom plate 3-1 and a side wall 3-2. The chute bottom plate 3-1 is connected to the spillway bottom plate, and the side wall 3-2 is connected to the spillway side wall 2. The primary sill 3 is a transverse diffusion type sill, where the chute bottom plate expands along the direction of water flow, causing the water flow to diffuse laterally along the chute. The main physical parameters of the primary sill 3 include the diffusion angle α1 of the left wall and the diffusion angle α2 of the right wall, the primary sill length L1, the outlet width B, the sill angle θ, and the side wall height h. 导 The process of determining the body shape parameters of the first level challenge 3 is as follows:

[0031] The diffusion angle α1 of the left wall of the first-level overhang is in the range of [0°, 7°], and / or the diffusion angle α2 of the right wall of the first-level overhang is in the range of [0°, 7°]. The diffusion angle is set to ensure that the water does not impact the downstream bank slope after flowing out of the overhang. When the overhang flow velocity is greater than 30m / s, the diffusion angle is preferably less than 5°;

[0032] The width B of the first-stage cantilever exit is determined according to the engineering conditions and the diffusion angles α1 and α2 of the left and right walls of the first-stage cantilever:

[0033] (1)

[0034] The value range of the first-level cantilever angle θ is [-30°, 30°]. For example, the first-level cantilever 3 can adopt one of the three forms of reverse arc cantilever type, flat cantilever type and depression angle cantilever type to adapt to different engineering conditions; at the same time, in order to cooperate with the second-level cantilever 4 to make the water tongue effectively cantilever and fully diffuse, the absolute value of the maximum cantilever angle does not exceed 30°.

[0035] Level 1 cantilever side wall 3-2 height h 导 Determined in accordance with the requirements of the current spillway design specifications (see the Spillway Design Specifications (SL253-2018) or Spillway Design Specifications (NB / T 10867-2021) for details).

[0036] According to the engineering conditions and downstream geological conditions, and on the premise of ensuring the safety of the project, the downstream scour depth T is initially planned. 设 , and according to the calculation formula of the scouring depth recommended by the current specification, it is deduced that the depth that satisfies T 设 The water inlet flow rate q 入设 :

[0037] (2)

[0038] Where: h t is the downstream water depth, m; H is the upstream and downstream difference, m; K is the bedrock scour coefficient.

[0039] Secondary embankment 4 is located immediately after primary embankment 3 and is a convex tooth embankment without a side wall. It forms a single convex tooth outside primary embankment 3, and its width gradually decreases along the direction of water flow. The main body parameters of secondary embankment 4 include the distances B1 and B3 between the secondary embankment 4 and the left and right walls of the primary embankment 3 outlet, the starting width B2 of the secondary embankment, the ending width B4 of the secondary embankment, the contraction angle β1 on the left side of the secondary embankment, the contraction angle β2 on the right side of the secondary embankment, the length L of the secondary embankment, the difference in embankment angle △θ between the secondary embankment and the primary embankment, the anti-arc radius R2 of the secondary embankment, and the horizontal surface area A of the secondary embankment. The body parameters of secondary embankment 4 are determined as follows:

[0040] The distance B1 between the secondary overhang 4 and the left wall of the primary overhang 3 outlet, and the distance B3 between the secondary overhang 4 and the right wall of the primary overhang 3 outlet are: B1 < B3, or B1 = B3, or B1 > B3. The connection position of the secondary overhang 4 and the primary overhang 3 can be flexibly adjusted to the center, left, or right according to the terrain and geological conditions of the downstream river channel; is the maximum discharge flow, B is the outlet width of the first-level embankment 3;

[0041] Secondary ridge 4 starting end width B2:

[0042] (3)

[0043] Horizontal length L of secondary ridge 4:

[0044] (4)

[0045] The value range of the left and right contraction angles β1 and β2 of the secondary sill 4 is between 5° and 10°. When the flow rate of the sill is greater, the value of the left and right contraction angles β1 and β2 of the secondary sill 4 is greater.

[0046] Width B4 of the end of the secondary ridge 4:

[0047] (5)

[0048] The angle difference △θ between the secondary ridge 4 and the primary ridge 3:

[0049] (6)

[0050] On the basis of the shape of the first-level ridge 3, according to the shape parameters L and △θ of the second-level ridge 4, the radius R2 of the second-level ridge anti-arc is calculated.

[0051] Verify the rationality of the preliminary design of the secondary ridge 4:

[0052] Calculate the water entry width C of the convex nose water tongue in the preliminary design 入 :

[0053] (7)

[0054] (8)

[0055] (9)

[0056] (10)

[0057] (11)

[0058] Where: γ is the diffusion coefficient of the convex flow nose; L 距 is the horizontal distance between the outer edge of the first-level overhang and the intersection of the downstream water surface, m; v is the flow velocity at the top of the first-level overhang, m / s; h1 is the vertical water depth at the top of the first-level overhang, m; h2 is the height difference between the top of the first-level overhang and the downstream water surface, m.

[0059] Calculate the water inlet flow rate per width q of the preliminary designed convex sill 入 :

[0060] (12)

[0061] when , then the body design is reasonable; otherwise, the design requirements can be met by appropriately increasing B2, L, and △θ.

[0062] The convex flow-lifting nose sill provided by the present invention will be specifically described below by taking a hydropower project as an example.

[0063] Example 1

[0064] The water depth of the downstream river channel 5 of a hydropower project is shallow and the geological conditions are poor. In order to reduce the scope and depth of downstream scour and reduce the amount of protective engineering, a convex nose sill is used at the end of the discharge structure, such as Figure 1 、 Figure 2 As shown, the convex flow nose sill of this example is composed of a first-level sill 3 with a diffusion-type side wall 3-2 at the outlet section of the spillway 1 and a second-level sill 4 without a side wall. In the figure, there is a downstream river channel 5, a downstream river channel scour pit 6, a flow-inducing water tongue 7 and a water tongue drop area 8.

[0065] The maximum discharge flow of the spillway of this project The flow rate is 478m³ / s, the width b of the spillway upstream of the nose sill is 5.00m, the height of the spillway side wall 2 is 5.50m, and the upstream and downstream water level difference H is 87.10m. According to the present invention, the plane design of the first-level sill section is a diffusion type, and the left and right walls 3-2 diffuse symmetrically to both sides, with diffusion angles α1 and α2 both being 2.985°. The width B of the chute at the end of the first-level sill section is 9.00m, the anti-arc radius R1 of the first-level sill is 70.00m, the sill angle θ is 20.786°, the elevation of the sill top is 162.00m, the water head H0 at the sill top is 72.60m, the height difference h2 between the sill top and the downstream water surface is 14.50m; the downstream water depth h t The downstream scour depth T is initially set to 8.00 m based on the engineering boundary and geological conditions. The inlet flow rate per width q that satisfies the T setting is obtained according to formula (2): 入设 =9.24m³ / (s·m); the two sides of the secondary embankment 4 are designed to be symmetrically contracted, and the contraction angles β1 and β2 are both 5°. According to formulas (3) to (6), the width B2 of the starting end of the secondary embankment is 4.74m, the length L of the secondary embankment is 5m, the width B4 of the end of the secondary embankment is 3.87m, and the angle difference △θ is 5.421°; according to R1, L, θ and △θ, the radius R2 of the secondary embankment is 58.99m; the secondary embankment 4 is arranged in the center, and the distances B1 and B3 from the left and right side walls of the outlet of the primary embankment 3 are both 2.13m; according to the body parameters of the primary embankment 3 and the secondary embankment 4, the water entry width C of the water tongue of the preliminary design convex embankment nose is obtained using formulas (7) to (11). 入 is 55.11m, and the single-width inlet flow rate q of the initial design scheme is obtained by formula (12): 入=8.67m³ / (s·m), which is less than q 入设 The value is 9.24m³ / (s·m), and the convex overhang shape meets the design requirements.

[0066] The results of the 1:50 hydraulic model test show that the convex nose sill water tongue provided by this embodiment has sufficient longitudinal and lateral diffusion, and the water inlet width C is 478m³ / s at the maximum discharge flow rate. 入 The maximum depth of the downstream scour pit is 51.80m, and the actual measured depth is 7.47m, which is 6.38m shallower than the 13.85m when there is only one level of embankment. This reduces the impact of downstream scour on project safety and river slope stability, reduces the amount of downstream protection work, and reduces project investment.

[0067] Example 2

[0068] The distance B1 between the secondary embankment and the left wall of the primary embankment outlet, and the distance B3 between the secondary embankment and the right wall of the primary embankment outlet, respectively, are: B1 > B3. The left contraction angle β1 of the secondary embankment ranges from [5° to 10°], and the right contraction angle β2 of the secondary embankment ranges from [5° to 10°]. Depending on the terrain and geological conditions of the downstream river channel, the connection position of the secondary embankment and the direction of the water tongue can be set off to the right. Setting the secondary embankment off to the right corresponds to different diverted water tongue shapes; diverted water tongues and symmetrical water tongues have different energy dissipation effects. The connection position of the secondary embankment and the primary embankment, combined with the lateral contraction angle β of the secondary embankment, are used to control the water tongue's landing point to adapt to the varying geological conditions of the downstream river channel.

[0069] Example 3

[0070] The distance B1 between the secondary embankment and the left wall of the primary embankment outlet, and the distance B3 between the secondary embankment and the right wall of the primary embankment outlet, are: B1 < B3. The left contraction angle β1 of the secondary embankment ranges from [5° to 10°], and the right contraction angle β2 of the secondary embankment ranges from [5° to 10°]. Depending on the terrain and geological conditions of the downstream river channel, the connection position of the secondary embankment and the direction of the water tongue can be set off to the left. Setting the secondary embankment off to the left corresponds to different diverted water tongue shapes; diverted water tongues and symmetrical water tongues have different energy dissipation effects. The connection position of the secondary embankment and the primary embankment, combined with the side contraction angle β of the secondary embankment, are used to control the water tongue landing point to adapt to the different geological conditions of the downstream river channel.

[0071] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A convex nose sill connected to a spillway (1), characterized in that: It includes the first level pick ridge (3) and the second level pick ridge (4); The first-level embankment (3) includes a chute bottom plate (3-1) that expands along the water flow direction and side walls (3-2) on both sides; The secondary sill (4) has no side wall, the width of the secondary sill (4) is smaller than the outlet width of the primary sill, and the width of the secondary sill (4) gradually shrinks along the direction of water flow; The outlet end of the first-stage sill (3) is connected to the second-stage sill (4) to form three-dimensional dispersed outlets at different elevations and plane positions, thereby achieving horizontal and vertical diffusion of the water tongue behind the sill; The difference in angle between the secondary ridge (4) and the primary ridge (3) , where the pick angle difference Δθ,°; is the maximum discharge flow, m³ / s; B is the outlet width of the first-level embankment (3), m.

2. The convex nose ridge according to claim 1, characterized in that: The secondary ledge (4) is tangentially connected to the chute bottom plate (3-1) to achieve smooth connection.

3. The convex nose ridge according to claim 1, characterized in that: The distance B1 between the secondary ridge (4) and the left wall of the primary ridge (3) outlet and the distance B3 between the secondary ridge and the right wall of the primary ridge outlet are: B1≤B3; the left contraction angle β1 of the secondary ridge (4) has a value range of [5°, 10°], and / or the right contraction angle β2 of the secondary ridge (4) has a value range of [5°, 10°].

4. The convex nose ridge according to claim 1, characterized in that: The distance B1 between the secondary ridge (4) and the left wall of the primary ridge (3) outlet and the distance B3 between the secondary ridge and the right wall of the primary ridge outlet are: B1>B3; the value range of the left contraction angle β1 of the secondary ridge (4) is [5°, 10°], and / or the value range of the right contraction angle β2 of the secondary ridge (4) is [5°, 10°].

5. The convex nose ridge according to claim 1, characterized in that: The value range of the angle θ of the first-level pick (3) is [-30°, 30°].

6. The convex nose ridge according to claim 1, characterized in that: The outlet width of the first level ridge (3) , where b is the width of the spillway before the cantilever, L1 is the length of the first-level cantilever (3), α1 is the diffusion angle of the left wall of the first-level cantilever (3), and α2 is the diffusion angle of the right wall of the first-level cantilever (3).

7. The convex nose ridge according to claim 1, characterized in that: The diffusion angle α1 of the left wall of the first-level ridge (3) has a value range of [0°, 7°]; and / or the diffusion angle α2 of the right wall of the first-level ridge (3) has a value range of [0°, 7°].

8. The convex nose ridge according to any one of claims 1 to 7, characterized in that: The horizontal length of the secondary ridge (4) , where the horizontal length of the secondary ridge (4) is , m; maximum downstream flow , m³ / s; the outlet width B of the first-level embankment (3), m.

9. The convex nose ridge according to claim 8, characterized in that: The starting end width of the secondary pick (4) , where the starting width of the secondary pick (4) is , m; maximum downstream flow , m³ / s; the outlet width B of the first-level embankment (3), m.

10. The convex nose ridge according to claim 8, characterized in that: The width of the end of the secondary pick (4) ,in, is the starting end width of the secondary pick (4), β1 is the left contraction angle of the secondary pick (4), and β2 is the right contraction angle of the secondary pick (4).

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