A design method for energy dissipation protection range of bottom shaft driven flap gate under multiple working conditions

Abstract

The present invention discloses a multi-condition bottom shaft driven flap gate energy dissipation protection range design method, which specifically relates to the technical field of steel dam gates, and specifically includes the following steps: given the hydraulic parameters of the incoming flow and the gate structure parameters; calculating the projection distance of the overflow water tongue before design, and the bottom plate split should be avoided at the projection distance of the water tongue; calculating the water depth after the critical jump to determine whether it is necessary to set up an energy dissipation pool; calculating the length of the main energy dissipation area and the length of the protection range, and obtaining the main energy dissipation area and the protection area range according to the energy dissipation and anti-scouring hydraulic calculation. The present invention obtains the main energy dissipation area and the protection area range according to the energy dissipation and anti-scouring hydraulic calculation, which facilitates engineering designers to quickly judge the energy dissipation protection range of the steel dam gate, and is suitable for the energy dissipation protection range design of various operating conditions of the steel dam gate.

Description

Technical Field

[0001] The present invention relates to the technical field of steel dam gates, and in particular to a design method for the energy dissipation protection range of a bottom shaft driven flap gate under multiple working conditions. Background Art

[0002] The bottom shaft driven flap gate (referred to as "steel dam gate") is mainly composed of gate leaves, bottom shaft, crank arm, hydraulic hoist and gate locking device. The gate leaves are fixed on the cantilever beam longitudinal main beam, and the cantilever fixed end of the longitudinal beam is rigidly connected to the bottom shaft. The water pressure can be transmitted to the bottom shaft through the gate leaf structure. The bottom shaft is subjected to both force and torque loads. The force is transmitted to the base through the bottom shaft fixed hinge support, and the torque is transmitted to the hydraulic opening and closing structure or locking device through the bottom shaft. The steel dam gate has the advantages of simple structure, flexible opening and closing, stepless adjustment of the gate opening without hindering flood control and navigation, and waterfall landscape can be formed through the falling flow at the top of the gate. It has been widely used in water gate design and has a very broad prospect.

[0003] So far, there is still a lack of relevant standards in the hydraulic design of steel dam gates. It mainly draws on the traditional sluice design specifications and single-stage waterfall empirical formulas. The flow through the steel dam gate is mainly overflow from the gate top or surface, which is quite different from the flow through the bottom of the traditional gate. The bottom flow energy dissipation and anti-impact design is not applicable. The design based on the single-stage waterfall empirical formula does not take into account the influence of factors such as gate opening and gate top overflow angle, which will cause calculation deviation of the ejection distance and directly affect the determination of the energy dissipation and anti-impact range.

[0004] From the actual operation situation, there are unreasonable flow patterns and operation modes through the gate, resulting in abnormal vibration or poor water flow connection. The existing design method does not involve the setting conditions of the steel dam gate energy dissipation pool and the determination of the energy dissipation protection range under arbitrary opening, which affects the operation and promotion of domestic steel dam gates. It is urgent to propose a design method for the energy dissipation protection range suitable for the complex operating conditions of steel dam gates. Summary of the invention

[0005] To this end, the present invention provides a method for designing the energy dissipation protection range of a bottom shaft driven flap gate under multiple working conditions to solve the problems raised in the background technology.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a method for designing the energy dissipation protection range of a bottom shaft driven flap gate under multiple working conditions, specifically comprising the following steps:

[0007] Step 1, giving the hydraulic parameters of the incoming flow and the gate structure parameters;

[0008] Step 2: Before hydraulic design, determine the maximum distance l of the overflow tongue of the steel dam gate d :

[0009] l d =(0.792h d+0.807p)(h0 / H) 0.404

[0010] Among them, h d is the downstream water depth, p is the drop height, h0 is the overflow head, and H is the distance from the center of the rotation axis to the highest point of the gate leaf when the gate is vertical;

[0011] Step 3: Determine the critical water jump depth h of the steel dam gate c ”:

[0012] h c =1.63(h0 / p) 0.879 p

[0013] Step 4: Determine the length l of the main energy dissipation zone of the steel dam gate m And the length of the protection zone l p :

[0014] l m =H sinθ+l d +1.2H

[0015] l p =H sinθ+l d +4.621h d

[0016] The gate opening is the angle θ between the gate centerline and the vertical line.

[0017] Preferably, in step 2, a sand retaining barrier is set upstream of the steel dam gate to determine the distance Δh from the center of the rotating shaft to the bottom plate; at a certain opening θ, the vertical distance from the highest point of the gate to the center of the rotating shaft is Hcosθ; the distance from the highest point of the gate to the gate bottom plate is the drop height p=Hcosθ+Δh.

[0018] Preferably, in step 2, the downstream water level h d and critical water jump h c The relative size of " is used as the criterion for setting up the stilling pool.

[0019] Preferably, if the downstream water level h d Greater than or equal to the critical post-jump water level h c ", then there is no need to set up a stilling pool; if the downstream water level h d Less than critical post-jump water level h c ", you need to set the height to (h c "-h d ) energy dissipation pool.

[0020] Preferably, the gate opening θ is 0 to 90°.

[0021] The present invention has the following advantages:

[0022] 1. The present invention determines the maximum distance of the overflow water tongue of the steel dam gate and the critical water jump depth of the steel dam gate by given the hydraulic parameters of the incoming flow and the gate structure parameters, and then obtains the length of the main energy dissipation area and the length of the protection area of ​​the steel dam gate. Compared with the prior art, the main energy dissipation area and the protection area are obtained according to the energy dissipation and anti-scouring hydraulic calculation, which is convenient for engineering designers to quickly judge the energy dissipation and protection range of the steel dam gate.

[0023] 2. The method for designing the energy dissipation protection range of the bottom shaft driven flap gate under multiple working conditions of the present invention sets the conditions of the energy dissipation pool of the steel dam gate and determines the energy dissipation protection range under any gate opening, thereby realizing the operation promotion of domestic steel dam gates and being suitable for the energy dissipation protection range design of various operating conditions of steel dam gates. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of hydraulic parameter characteristics of overflow water tongue when the steel dam gate is blocking water;

[0025] Figure 2 The relationship between the ejection distance of the steel dam gate and the overflow head;

[0026] Figure 3 is the relationship between the ejection distance of the steel dam gate and the height of the drop flow;

[0027] Figure 4 The relationship between the water depth after the critical jump of the steel dam gate and the overflow head;

[0028] Figure 5 The length fitting curve of the main energy dissipation zone of the steel dam gate;

[0029] Figure 6 It is the fitting curve of the energy dissipation protection range of the steel dam gate.

[0030] Figure 7 Calculation flow chart for steel dam gate DETAILED DESCRIPTION

[0031] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment provides a method for designing the energy dissipation protection range of a bottom shaft driven flap gate under multiple working conditions. This method is simple, accurate and practical. At the same time, this method can provide a reference for calculating the energy dissipation protection range of similar top overflow structures.

[0034] To further illustrate the content and effects of the present invention, the detailed description is as follows in conjunction with the accompanying drawings:

[0035] See also Figure 1 to Figure 7 , Figure 1 As shown in the figure, the main gate structural parameters are gate height H, gate opening θ, shaft radius Δh and drop height p; the main flow hydraulic parameters are overflow head h0, overflow head projection distance l d , hydraulic jump length l j , downstream water depth h d wait.

[0036] like Figure 2-3 As shown, the water tongue projection distance l d It is related to the drop height p and the overflow head h0. Through fitting analysis, it can be obtained that the relative value of the water tongue projection distance l under different downstream water depths is d / H has a certain functional relationship with the relative value of overflow head h0 / H, and the regularity between the ejection distance and the drop height is not obvious. The power index value of the relative value of overflow head is relatively concentrated, and its average value of 0.404 is taken as the power index of the relative value of overflow head. The product coefficient K is related to the water depth h d There is a certain linear relationship. Therefore, the projection distance expression is obtained:

[0037] l d / H=K·(h0 / H) 0.404 (1)

[0038] The key is to get the coefficient polynomial K before the power function. According to the relative value of the projectile distance l d / H is relative to the downstream water depth h d / H is related to the relative value of the drop height p / H. Preliminary analysis shows that this coefficient is related to the relative value of the downstream water depth h d / H is positively correlated, and further analysis of coefficient K and water depth h d The relationship is k1 = 0.792, and the coefficient K is regarded as the downstream water depth h d And the influence of the drop height p, now deduct the water depth influence coefficient k1, and get the drop influence coefficient k2 = 0.807. Therefore, the fitting empirical formula is obtained:

[0039] l d =(0.792h d +0.807p)(h0 / H) 0.404 (2)

[0040] p=H cosθ+Δh (3)

[0041] Where, p is the height of the drop (m); H is the distance from the gate top to the center of the rotating shaft (m); Δh is the vertical distance between the rotating shaft and the bottom plate (m).

[0042] Establish the water depth after the jump h c The relationship between the overflow head h0 and the overflow head h0 is dimensionless, and the ratio of the critical post-jump water depth to the drop height h0 is calculated. c ” / p is the vertical axis, and the ratio of overflow head to drop height h0 / p is the horizontal axis (see Figure 4 ), and we get by linear fitting:

[0043] h c = 1.63p(h0 / p) 0.879 (4)

[0044] Where: h c ” is the water depth after the jump, h0 is the overflow head, and p is the drop height.

[0045] The range of the main energy dissipation zone is related to factors such as gate height, opening angle, single-width flow, and downstream water depth. Considering that the drop-flow ejection distance mentioned above already includes multiple influencing factors, from another perspective, the main energy dissipation zone should be closely related to the drop-flow position (ejection distance). For simplicity, the main energy dissipation zone length l is proposed. m The gate height H, opening angle θ and projection distance l d The relationship between:

[0046] (l m -H sinθ-l d ) / H=ξ (5)

[0047] In the formula, (l m -H sinθ-l d ) is the length of the main energy dissipation area minus the horizontal projection distance and projection distance of the gate.

[0048] The gate opening is 0-90°. According to the test, the influence range is the largest when the opening angle is 45°. Therefore, it is recommended that the gate opening θ be 45° (unfavorable working condition). According to the unfavorable working condition 45° opening, the main energy dissipation zone range of 4 groups of working conditions with different gate heights H is established as follows: Figure 5 As shown, the coefficient ξ is obtained by fitting, which is slightly conservative.

[0049] l m =H sinθ+l d +1.2H (6)

[0050] Where H sinθ is the horizontal projection of the gate, l d is the water tongue projection distance.

[0051] Similarly, establish a simplified protection range l p Calculation formula:

[0052] (l p -H sinθ-ld ) / H=ψ(h d / H) (7)

[0053] In the formula, ψ is the coefficient. The 45° opening under relatively unfavorable working conditions is still considered as the basic condition. According to different overflow head h0 and downstream water depth h d , 45° opening test condition flow rate adjustment range, establish the relationship as follows Figure 6 As shown in Figure 2, the coefficient ψ is approximately 4.621.

[0054] l p =H sinθ+l d +4.621h d (8)

[0055] In the formula, h d is the downstream water depth, H sinθ is the horizontal projection of the gate, l d is the water tongue projection distance.

[0056] The length of the main energy dissipation area l m Determine the length l of the protection range under the steel dam gate p After the water tongue in this area enters the water, it is deflected by the bottom plate of the gate to form two wall-attached jets. The small wall-attached jet diffuses upstream and causes the water surface behind the gate to fluctuate and oscillate. The large wall-attached jet jumps downstream to form a surface flow vortex zone. This area is designed as the main energy dissipation zone, and the uniform water flow is determined by the scope of the protection zone.

[0057] Example 2

[0058] Based on Example 1, taking the gate height H = 5m, the gate operation angle of 0-90° (one-way water retaining condition), and the overflow head h0 = 0.5m as an example, at the downstream water level h d If the downstream water level is unknown, assume that d Below the gate drop height p, if the downstream water level h d If known, take the average water level over many years;

[0059] Step 1: Before hydraulic design, determine the maximum distance l of the overflow water tongue of the steel dam gate d ;

[0060] l d =(0.792h d +0.807p)(h0 / H) 0.404

[0061] Among them, h d is the downstream water depth, p is the drop height, h0 is the overflow head, and H is the distance from the center of the rotation axis to the highest point of the gate leaf when the gate is vertical;

[0062] Step 2: Determine the critical water jump depth h of the steel dam gatec ”:

[0063] h c =1.63(h0 / p) 0.879 p

[0064] Step 3: Determine the main energy dissipation area of ​​the steel dam gate m And the length of the protection zone l p :

[0065] l m =H sinθ+l d +1.2H

[0066] l p =H sinθ+l d +4.621h d

[0067] The gate opening is the angle θ between the gate centerline and the vertical line;

[0068] As a preferred technical solution of the present application, in step 1, a sand barrier is set upstream of the steel dam gate to determine the distance Δh from the center of the rotating shaft to the bottom plate; at a certain opening θ, the vertical distance from the highest point of the gate to the center of the rotating shaft is H cosθ; the distance from the highest point of the gate to the gate bottom plate is the drop height p=H cosθ+Δh;

[0069] Table 1 Energy dissipation protection range parameters of steel dam gate with single gate height of 5m

[0070]

[0071] Note: When △h≤0, no stilling pool needs to be designed; when △h>0, a stilling pool with corresponding depth △h needs to be designed.

[0072] Through the downstream water level h d and critical water jump h c The relative size of " is used as the criterion for setting up the stilling pool:

[0073] If the downstream water level h d Greater than or equal to the critical post-jump water level h c ", then there is no need to set up a stilling pool; if the downstream water level h d Less than critical post-jump water level h c ", you need to set the height to (h c "-h d ) energy dissipation pool.

[0074] According to this design method, under the one-way water retaining condition with a gate height of 5m and an overflow head of 0.5m, there is no need to set up an energy dissipation pool, and the main energy dissipation area is within 12m. The energy dissipation protection area increases with the increase of water depth and is controlled within 22m below the gate.

[0075] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A design method for the energy dissipation protection range of a bottom shaft driven flap gate under multiple working conditions, characterized in that: The specific steps include: Step 1, giving the hydraulic parameters of the incoming flow and the gate structure parameters; Step 2: Before hydraulic design, determine the maximum distance l of the overflow tongue of the steel dam gate d : <h2 style=";text-align:left;direction:ltr">l<h2 style=";text-align:left;direction:ltr"> d <h2 style=";text-align:left;direction:ltr"> (0.792h<h2 style=";text-align:left;direction:ltr"> d <h2 style=";text-align:left;direction:ltr"> +0.807p)(h0 / H)<h2 style=";text-align:left;direction:ltr"> 0.404 Among them, h d is the downstream water depth, p is the drop height, h0 is the overflow head, and H is the distance from the center of the rotation axis to the highest point of the gate leaf when the gate is vertical; Step 3: Determine the critical water jump depth h of the steel dam gate c ”: h c ”=1.63(h0 / p) 0.879 p Step 4: Determine the length l of the main energy dissipation zone of the steel dam gate m And the length of the protection zone l p : <h2 style=";text-align:left;direction:ltr">l<h2 style=";text-align:left;direction:ltr"> m <h2 style=";text-align:left;direction:ltr"> (Hsinθ+l)<h2 style=";text-align:left;direction:ltr"> d <h2 style=";text-align:left;direction:ltr"> +1.2H the p =Hsinθ+l d +4.621h d The gate opening is the angle θ between the gate centerline and the vertical line.

2. A method for designing the energy dissipation protection range of a multi-operating-condition bottom shaft driven flap gate according to claim 1, characterized in that: In step 2, a sand retaining bank is set upstream of the steel dam gate to determine the distance Δh from the center of the rotating shaft to the bottom plate; when the gate opening θ is 0-90°, the vertical distance from the highest point of the gate to the center of the rotating shaft is Hcosθ; the distance from the highest point of the gate to the gate bottom plate is the drop height p=Hcosθ+Δh.

3. The method for designing the energy dissipation protection range of a multi-operating-condition bottom shaft driven flap gate according to claim 2 is characterized in that: In step 2, the downstream water level h d and critical water jump h c The relative size of " is used as the criterion for setting up the stilling pool.

4. A method for designing the energy dissipation protection range of a multi-operating-condition bottom shaft driven flap gate according to claim 3, characterized in that: If the downstream water level h d Greater than or equal to the critical post-jump water level h c ", then there is no need to set up a stilling pool; if the downstream water level h d Less than critical post-jump water level h c ", you need to set the height to h c ”-h d The stilling pool.

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