CN209619962U - A kind of anti-whirlpool device of rectification - Google Patents

Abstract

The utility model discloses a rectification and anti-vortex device. The rectification and anti-vortex device is arranged at the upstream head of an inverted siphon water inlet, and an exhaust riser, a rectification curtain wall and a diversion and anti-vortex hole are arranged at the head of an inlet forebay. The exhaust riser eliminates the air bubbles entering the forebay; the rectifying curtain wall blocks the water surface fluctuation caused by the energy dissipation of the falling flow stilling pool and propagates to the forebay; the outlet water flow of the diversion anti-vortex hole enters the forebay in a submerged form, and flows slowly The flow state makes the water flow into the pool enter the inverted siphon water inlet smoothly and smoothly, avoiding the flow state conversion in the forebay and the vortex before the water inlet. The utility model has the advantages of: avoiding the water-air mixed flow problem caused by the energy dissipation of the water flow in the forebay, so as to adapt to the large change in the water level of the forebay caused by the change of operating conditions; In the case of keeping the harmful vortex in front of the water inlet; in order to maintain the smooth operation of the inverted siphon pipeline and enhance the safety performance of the inverted siphon pipeline.

Description

A rectifying anti-vortex device

technical field

The utility model relates to the technical field of inverted siphon pipeline water delivery engineering, in particular to a rectifying and anti-vortex device.

Background technique

Inverted siphon pipeline is a cross-flow crossing structure often used in water transportation projects across rivers and other obstacles. Under normal operation, the inverted siphon pipeline is in a full flow state and belongs to pressurized pipe flow. The water level difference between the inlet and outlet of the inverted siphon depends on the head loss between the inlet and outlet of the inverted siphon (including loss along the way h _f and local loss h _i ). The head loss between the inlet and outlet of the inverted siphon pipe is related to many factors such as the diversion flow, pipe length, cross-sectional shape and size, axis layout and pipe surface roughness. If the cross-sectional shape and size of the inverted siphon pipe remain unchanged, the inverted siphon The head loss along the channel can be calculated by formula (1):

Its local head loss is calculated by formula (2):

In formula (1) and formula (2): _hf —the loss along the way of the inverted siphon pipe, n—the surface roughness coefficient of the pipe, L—the length of the pipe, R—the hydraulic radius of the pipe, A—the cross section of the water section of the pipe surface area, Q—pipeline water flow, h _i —pipeline local loss, —The local head loss coefficient of the pipeline.

In the case that the pipeline axis layout and cross-sectional shape and size have been determined, the size of the head loss still varies with the diversion flow and the surface roughness of the pipeline. When the flow rate of the water transmission project changes in a large range during operation, or the inverted siphon pipe is long, the surface roughness coefficient of the pipe is difficult to accurately estimate or the surface roughness changes during operation, such as prestressed steel cylinder concrete pipes The surface roughness coefficient n may be between 0.011 and 0.0135, so the head loss between the inlet and outlet of the inverted siphon pipe will also vary greatly, so that the water level difference between the inlet and outlet of the inverted siphon project will occur during normal operation. Substantial changes. However, the elevation of the upstream and downstream water delivery channels of the inverted siphon pipeline inlet is often determined according to the topographical conditions and a special operating condition of the water delivery project. In general, the design is based on the maximum diversion flow Q _max to determine the upstream and downstream of the inverted siphon inlet. The elevation and section size of the water delivery channel downstream of the outlet. The water level difference between the water level of the diversion channel upstream of the inverted siphon inlet and the water level in the downstream water delivery channel of the outlet is relatively fixed, and it is impossible to change with the head loss of the inverted siphon pipeline, which will cause a large change in the water level of the forebay 7 of the inverted siphon inlet. Large changes in the water level of the forebay 7 often cause problems in the following two aspects: (1) Insufficient submersion depth of the water inlet forms a suction vortex and entrains air into the inverted siphon pipe; The torrent flow state enters the forebay, and produces a hydraulic jump in the forebay, forming a water-air two-phase flow, carrying a large number of air bubbles into the inverted siphon pipe. The air entering the inverted siphon pipe is easy to gather to form an air bag, and the air bag oscillates with the change of the pressure fluctuation, which may not only cause unstable water flow in the pipe, increase the fluctuating pressure, but also cause an air explosion and induce a safety accident.

In order to solve the problem that the water head loss of the inverted siphon pipeline changes due to the change of the diversion flow and the surface roughness of the pipeline during operation, which leads to a large drop in the water level of the forebay and the problem of air intake and unstable operation of the inverted siphon pipeline, as shown in Figure 1. The existing technical scheme is to arrange a control gate at the outlet section of the inverted siphon pipeline. The flow capacity of the inverted siphon pipeline is designed according to the maximum flow rate Q _max of water diversion under the condition that the gate of the inverted siphon outlet is fully opened and the surface roughness of the pipeline may be the maximum value n _max . For other non-design operating conditions where the water diversion flow and surface roughness of the pipeline are reduced, the operation mode of controlling the partial opening of the gate can be adopted to keep the water level of the forebay within the safe operating water level range that can maintain the inverted siphon pipeline, so as to ensure the safety of the inverted siphon project normal operation.

But this method has the following defects:

1) It is necessary to control the opening of the outlet gate and adjust the water level of the forebay according to the surface roughness of the inverted siphon and the size of the water diversion flow. The operation and management process during operation is relatively complicated;

2) The diversion flow of the inverted siphon project needs to adjust the opening of the outlet gate. For the inverted siphon pipeline with a length of several kilometers, the rapid change of the gate opening may cause excessive water hammer pressure; on the other hand, if the gate is in operation If the middle lock fails and suddenly falls and closes, it may also cause excessive water hammer pressure to rupture the pipeline, which poses a certain safety hazard.

3) The water level of the forebay is raised by the partial operation of the gate, which increases the water flow velocity at the outlet of the inverted siphon pipe. Energy dissipation facilities need to be designed at the outlet, and the stability of the water flow in the downstream diversion channel is poor.

In order to prevent harmful suction vortices from being generated in front of the inverted siphon water inlet, and to avoid water pressure fluctuations caused by air entering the inverted siphon pipe, another existing technical solution is to set up several vortex elimination beams near the water inlet, through the vortex elimination The interference of the beam prevents the formation of circulation flow in front of the water inlet to avoid the suction vortex and prevent the vortex from entraining air into the inverted siphon pipe.

This technical solution can only solve the problem of the suction vortex before the water inlet of the inverted siphon pipe. For the operation situation in which the water level of the forebay is lowered due to the change of the water delivery flow and the change of the surface roughness of the pipeline, the water flow of the diversion channel enters the forebay in a rapid flow state, and a hydraulic jump is generated in the forebay to cause the water body to be mixed with a large number of air bubbles. The problem that the water flow carries air bubbles into the inverted siphon pipe cannot be solved by its existing technical solutions. At the same time, the large fluctuations in the water surface caused by the energy dissipation of the water flow in the forebay will also affect the smooth operation of the inverted siphon pipeline.

Utility model content

Aiming at the defects of the prior art, the utility model provides a rectifying and anti-vortex device, which can effectively solve the above-mentioned problems in the prior art.

In order to realize above utility model purpose, the technical scheme that the utility model takes is as follows:

A rectification and anti-vortex device, comprising: falling flow stilling pool 1, tail sill 2, ventilation pipe 3, rectification curtain wall 4, diversion anti-vortex hole 5, exhaust lift sill 6, front pool 7, water inlet 8 and partition pier 9;

The falling flow stilling pool 1 is adjacent to the diversion channel, and the tail sill 2 is set at the end of the falling flow stilling pool 1 to form an energy dissipation water cushion, and the vent pipe 3 is arranged behind the tail sill 2 to connect the flow surface behind the sill with the atmosphere;

There are multiple levels of falling flow stilling basin 1, and the height of the falling sill of each level of falling flow stilling basin 1 is generally 3.0~6.0m, and the exhaust rising sill 6 is arranged on the bottom plate at the end of the falling flow stilling basin 1 of the last level;

The rectifying curtain wall 4 and the diversion anti-vortex hole 5 are arranged 3.0-5.0m downstream of the exhaust sill 6. The outlet of the diversion anti-vortex hole 5 is directly connected to the forebay 7, and the water inlet 8 is arranged at the end of the forebay 7.

The diversion anti-vortex hole 5 is located between the last falling flow stilling pool 1 and the forebay 7, and its flow cross section is rectangular. The width of the diversion anti-vortex hole 5 is the same as that of the forebay 7. The diversion anti-vortex hole The height of the outlet orifice of 5 is determined according to the slow flow state of the water entering the forebay 7. In order to keep the water flow stable, the maximum Floyd's number of the outlet flow can be 0.50-0.70.

The rectifying curtain wall 4 is located on the upper part of the entrance of the diversion and anti-vortex hole 5, and the rectifying curtain wall 4 is vertically arranged in a rectangular shape. The top is about higher than the highest water level during the normal operation of the last level of falling flow stilling pool 1 . The rectifying curtain wall 4 cuts off the connection between the water surface of the falling flow stilling pool 1 and the water surface of the forebay 7, preventing the water surface fluctuation caused by the falling flow energy dissipation from spreading to the forebay 7, and avoiding affecting the stability of the water flow in the forebay 7 and the pipeline.

The exhaust sill 6 is located on the bottom plate of the last stage of the falling flow stilling pool 1 before the diversion anti-vortex hole 5. The distance from the exhaust sill 6 to the entrance of the diversion anti-vortex hole is 3.0-5.0m. The top elevation is about 0.5m higher than the inlet floor elevation of the diversion anti-vortex hole 5 . The exhaust riser 6 constrains the water flow upwards, and accelerates the air bubbles involved in the water body to float up during the energy dissipation process of the falling flow by means of the bending of the streamline, so as to prevent the air bubbles carried by the water flow from entering the forebay 7 through the diversion anti-vortex holes 5 .

The ventilation pipe 3 generally adopts a circular pipe, and the outlet of the ventilation pipe 3 is arranged on the downstream surface of the end sill 2 of the falling flow stilling pool 1 near the top of the sill, and the outlet adopts a round hole with an aperture of about 10 cm. The width of the tail sill 2 of the flow stilling pool 1 is determined.

As a preference, the length L of the slump stilling pool 1 is composed of the drop length _l1 of the water tongue and the length _l2 of the sag height hydraulic jump, and is determined according to the height of the sill and the maximum single-width flow rate during normal operation. The drop length of the water tongue can be estimated according to formula (3):

In formula (1): q—single-width flow at the sill; P—height of the sill; h ₀ —deep flow. For the drop distance of the high ridge water tongue, it can be estimated by formula (4):

The length of the falling water and the high hydraulic jump:

l ₂ =3.2h ₂ (5)

In formula (5): h ₂ —the second conjugate water depth of falling water jump, calculated according to the hydraulic jump formula.

As a preference, the series of falling flow stilling pool 1 depends on the variation range of the water level in the forebay 7 of the water inlet 8 during the normal operation of the inverted siphon engineering; assuming that the maximum change value of the water level in the forebay of the water inlet is ΔH _max , then the falling flow stilling The series number N of the pool is calculated according to formula (6):

N＝ _ΔHmax /(3～6) (6)

As a preference, the height of the tail sill 2 at the end of the falling flow stilling pool 1 is between 1/3 to 1/4 of the height of the falling sill, and the height of the last stage of falling flow stilling pool 1 is reduced by 0.3 to 0.6m; its length Increase the length by 3m.

As a preference, the outlet top plate elevation of the diversion anti-vortex hole 5 is lower than the minimum operating water level of the forebay 7, and the minimum submerged depth of the outlet is kept not less than 0.5m. The curved surface is rounded to facilitate smooth and stable water flow at the inlet.

As a preference, the diversion anti-vortex hole 5 and the forebay 7 are evenly divided into holes according to the number of inverted siphon pipes by the partition piers 9 arranged along the water flow direction, so that each inverted siphon pipe can maintain the forward siphon under independent and combined operating conditions. The water flow in the pool is smooth.

Compared with the prior art, the utility model has the advantages of:

1) The utility model consumes the excess energy between the diversion canal and the normal operating water level of the forebay through the multi-stage downflow stilling pool, so that the water flow energy of the last downflow stilling pool matches the energy required for the normal operation of the forebay , The multi-stage falling flow stilling pool can automatically adjust the water level of the last level falling flow stilling pool according to the flow situation of the diversion canal, avoiding the problem of water-air mixed flow caused by the energy dissipation of the water flow in the forebay, so as to adapt to the water level of the forebay due to the operation Large changes caused by changing conditions.

2) The slow flow state in the forebay has been maintained under different operating conditions, and the flow state will not change due to changes in operating conditions. The mainstream flow trajectory in the forebay is relatively fixed, avoiding the circular flow in front of the water inlet, and eliminating the formation of The unfavorable flow of the vortex can keep the harmful vortex from forming in front of the water inlet when the water level of the forebay changes greatly.

3) The water surface of the energy dissipation area is separated from the water surface of the forebay by means of the rectifying curtain wall, and the water flow energy dissipation area and the forebay are independent of each other, which eliminates the influence of large fluctuations in the water surface caused by the energy dissipation of the water flow on the water flow in the forebay, effectively reducing the The water surface of the forebay fluctuates; with the help of the exhaust function of the exhaust riser, the air bubbles involved in the water flow during the energy dissipation process of the falling flow are prevented from flowing into the forebay, so as to maintain the smooth operation of the inverted siphon pipe.

4) When the water flow of the inverted siphon project changes, there is no need to change the gate opening, avoiding the water hammer pressure caused by the change of the gate opening, and enhancing the safety performance of the inverted siphon pipeline operation.

5) It can automatically adapt to large changes in the water level of the forebay, simplifying the operation and management process of the inverted siphon project.

Description of drawings

Fig. 1 is the longitudinal section schematic diagram of prior art inverted siphon pipeline;

Fig. 2 is a three-dimensional view of the rectification and anti-vortex device of the utility model;

Fig. 3 is a structural schematic diagram of a rectifying and anti-vortex device according to Embodiment 1 of the present utility model;

Fig. 3A is a schematic longitudinal sectional view of the rectifying and anti-vortex device according to Embodiment 1 of the present utility model;

Fig. 3B is a plane structure diagram of the rectifying and anti-vortex device according to Embodiment 1 of the present utility model.

The meanings of the numbers in the figure are: 1. Falling flow stilling pool; 2. End sill; 3. Ventilation pipe; 4. Rectification curtain wall; 5. Diversion anti-vortex hole; 6. Exhaust sill; ; 8. Water inlet; 9. Separation pier.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and examples.

Example 1

As shown in Figures 2 and 3, the length of the inverted siphon pipe in this embodiment is about ^11,000m , and two prestressed concrete pipes with an inner diameter of 2.8m are arranged side by side. The rate coefficient ranges from 0.012 to 0.013, and the head loss between the inlet and outlet of the inverted siphon ranges from 16.6m to 28.8m. Under normal operating conditions, the water level of the forebay varies by about 12.0m.

The structure of the rectifying and anti-vortex device is shown in Figure 2, including the three-stage falling flow stilling pool 1 close to the diversion channel, and the falling heights of the three-stage falling flow stilling pool 1 are 4.5m, 4.5m and 4.1m respectively. To meet the requirements of the change range between the water level of the forebay 7 and 12.0m. A tail sill 2 is set at the end of the falling flow stilling pool 1, so that the stilling pool is backed up with water to meet the required depth of the water cushion for forming the falling flow hydraulic jump. The length of the pool 1 and the height of the sill 2 of each level of the falling flow stilling pool 1 are designed and calculated according to the requirements of the stable submerged water flow in the falling flow stilling pool under the maximum diversion flow of the project during the operation period:

h ₁ , h ₂ —conjugate water depth before and after the hydraulic jump (m), h _k —critical water depth corresponding to the maximum diversion flow (m); P—height of the sill (m).

The length of the falling flow stilling pool 1 is the sum of the drop distance of the water tongue and the length of the hydraulic jump, and the drop distance of the water tongue is:

The jump length l ₂ of the falling water jump is:

l ₂ =3.2h ₂ (10)

The height a of the tail sill is:

a=σh ₂ -h ₃ (11)

In the formula: a - height of stern sill (m); σ - hydraulic jump submersion coefficient, generally taken as 1.05~1.1; h ₃ - water depth of sill top of stern sill (m). The width of the falling flow stilling basin is 13.0m, and the maximum diversion flow rate is 39.0m ³ /s. The lengths of the third-level stilling basins calculated from formulas (1) to (5) are 13.42m, 13.42m and 13.19m respectively. The tail sill heights are 1.37m, 1.37m and 1.33m respectively.

The exhaust sill located on the rear floor of the third-stage slump stilling tank 1 can also serve as the tail sill function of the third-stage slump stilling tank 1, and the top elevation of the exhaust sill 6 is higher than the diversion and anti-vortex holes 5 The elevation of the bottom plate of the inlet is about 0.5m, or its height may be taken as 1.5~2.0 times of the height of the corresponding stern sill. A rectification curtain wall 4 is installed 3-5m behind the exhaust sill 6, and the top of the rectification curtain wall 4 is higher than the highest operating water level (super high value 0.3m). The diversion anti-vortex hole 5 and the forebay 7 are symmetrically divided into two holes by the pier 9 arranged along the center line, so that the two inverted siphon pipes can keep the water flow in the forebay smooth under both independent and combined operating conditions. The width of the diversion anti-vortex hole 5 is the same as the width of the forebay 7, which is 5.0m. When the height of the outlet of the diversion anti-vortex hole 5 is 39m ³ /s according to the maximum diversion flow rate, the Floyd's number of the outlet water flow is The control condition of 0.5 is designed, and the calculation shows that the height of the outlet orifice is 1.8m, and the top elevation of the outlet of the diversion anti-vortex hole 5 is about 1.0m lower than the minimum water level of the forebay 7 in normal operation, so as to ensure that the diversion anti-vortex hole 5 The water flowing into the forebay is in a slow flow state under normal operating conditions, while taking into account the reduction of water surface fluctuations and stabilizing the water flow.

Those of ordinary skill in the art will appreciate that the embodiments described here are to help readers understand the implementation method of the present utility model, and it should be understood that the protection scope of the present utility model is not limited to such special statements and examples . Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the utility model without departing from the essence of the utility model, and these variations and combinations are still within the protection scope of the utility model.

Claims (6)

1. A rectification and anti-vortex device, characterized in that it comprises: falling flow stilling pool (1), tail sill (2), ventilation pipe (3), rectification curtain wall (4), diversion anti-vortex hole (5) , exhaust sill (6), forebay (7) and water inlet (8); The falling flow stilling pool (1) is adjacent to the diversion channel, and the end of the falling flow stilling pool (1) is provided with a tail sill (2) to form an energy dissipation water cushion, and a ventilation pipe (3) is installed behind the tail sill (2) to avoid Negative pressure and steady drop flow appear on the flow surface; The falling stilling pool (1) has multiple levels, and the height of the falling sill of each level of falling stilling pool (1) is generally 3.0-6.0m, and it is arranged on the bottom plate at the end of the falling stilling pool (1) of the last level Exhaust riser (6); Arrange the rectifying curtain wall (4) and diversion anti-vortex holes (5) at 3.0-5.0m downstream of the exhaust sill (6), the outlet of the diversion anti-vortex holes (5) is directly connected to the forebay (7), and the water inlet (8) Arranged at the end of the forebay (7); The diversion anti-vortex hole (5) is located between the last stage of falling flow stilling pool (1) and the forebay (7), and its flow cross section is rectangular, and the width of the diversion anti-vortex hole (5) is the same as that of the forebay ( 7) The width is the same, and the height of the outlet orifice of the diversion anti-vortex hole (5) is determined according to the slow flow state of the water entering the forebay (7). In order to keep the water flow stable, the maximum water flow at the outlet is 0.50-0.70 ; The rectifying curtain wall (4) is located on the upper part of the entrance of the diversion and anti-vortex hole (5). The rectifying curtain wall (4) is vertically arranged in a rectangular shape. The width of the rectifying curtain wall (4) is the same as that of the front pool (7). The rectifying curtain wall (4) The top is higher than the highest water level of the forebay (7), and the top of the rectifying curtain wall (4) is about higher than the highest water level of the last stage of the falling stilling pool (1) during normal operation; the rectifying curtain wall (4) cuts off the falling stilling pool ( 1) The connection between the water surface and the water surface of the forebay (7) prevents the water surface fluctuation caused by the energy dissipation of the falling flow from propagating into the forebay (7), and prevents its water surface fluctuation from affecting the stability of the water flow in the forebay (7); The exhaust riser (6) is located on the bottom plate of the last stage of the falling flow stilling pool (1) before the diversion anti-vortex hole (5), and the distance between the exhaust riser (6) and the inlet of the diversion anti-vortex hole The elevation of the top of the sill is 3.0-5.0m, and the elevation of the top of the sill is about 0.5m higher than that of the inlet bottom plate of the diversion anti-vortex hole (5). The air bubbles involved in the water body drift and float up, preventing the water flow from carrying air bubbles into the forebay (7) through the diversion anti-vortex hole (5); The ventilation pipe (3) generally adopts a circular pipe, and the outlet of the ventilation pipe (3) is arranged on the downstream surface of the tail sill (2) of the falling flow stilling pool (1) near the top of the sill, and the outlet adopts a circular hole with a diameter of about 10 cm. The outlet number of the ventilation pipe (3) is determined according to the width of the tail sill (2) of the falling flow stilling pool (1). 2. A rectifying and anti-vortex device according to claim 1, characterized in that: the length L of the falling flow stilling pool ( ₁ ) is composed of the falling length l1 of the water tongue and the length _l2 of the falling high water jump. The sill height and the maximum single-width flow rate during normal operation are determined; the water tongue drop length is estimated according to formula (1): In the formula (1): q—single-width flow rate at the sill; P—the height of the sill; h ₀ —the depth of the incoming water; the falling distance of the water tongue at the high sill is estimated by formula (2): The length of the falling water and the high hydraulic jump: l ₂ =3.2h ₂ (3) In formula (2) and formula (3): h _k —critical water depth of falling ridge water flow; h ₂ —second conjugate water depth of falling water jump, calculated according to hydraulic jump formula. 3. A rectifying and anti-vortex device according to claim 1, characterized in that: the number of stages of the falling flow stilling pool (1) depends on the change of the water level of the inverted siphon inlet forebay (7) during the normal operation of the inverted siphon project range; assuming the maximum change in water level of the inverted siphon inlet forebay (7) is ΔH _max , then the series N of the falling flow stilling tank is calculated according to formula (4): N=ΔH _max /(3~6) (4). 4. A rectifying and anti-vortex device according to claim 1, characterized in that: the height of the tail sill (2) at the end of the falling flow stilling pool (1) is between 1/3 and 1/4 of the height of the falling sill, And the height of the last stage of falling flow stilling pool (1) is reduced by 0.3-0.6m. 5. A rectifying and anti-vortex device according to claim 1, characterized in that: the elevation of the outlet top plate of the diversion anti-vortex hole (5) is lower than the minimum operating water level of the forebay (7), and the minimum submerged depth of the outlet is kept not less than 0.5m, the upper and lower edges of the inlet of the diversion anti-vortex hole (5) are rounded with arc surface or elliptical surface, so that the inlet water flow is smooth and stable. 6. A kind of rectification and anti-vortex device according to claim 5, characterized in that: it also includes a spacer (9), and the diversion anti-vortex hole (5) is formed by the spacer (9) arranged along the water flow direction according to the inverted siphon The number of pipes is evenly divided into holes, so that each inverted siphon pipe can maintain smooth water flow in the forebay under independent and combined operating conditions.