CN101349047A - Air-entrained curve ladder energy dissipator in the flood discharge tunnel - Google Patents

Abstract

An aeration-type curved ladder energy dissipator in a spillway tunnel, including an aeration device installed at the entrance of a curved connection tunnel body between two parallel spillway tunnels or pressurized tunnels with different heights and a downstream spillway tunnel; The ladder energy dissipator arranged on the bottom of the body is located behind the adjusted slope section where the curve connects the bottom of the cave body. From the high position to the low position, there are incline step section, transition step section and horizontal step section in sequence. The aeration device can effectively aerate the inlet high-speed water flow, reduce or avoid the possibility of cavitation damage to the steps, and the step energy dissipator can transition the direction of the high-speed water flow to be parallel to the step slope, and adjust the curve to connect the cave body reduce the flow velocity at the outlet of the curve connecting the cave body, and reduce the erosion of the downstream spillway tunnel.

Description

Air-entrained curve ladder energy dissipator in the flood discharge tunnel

technical field

The invention belongs to energy dissipating facilities used in water conservancy and hydropower projects, in particular to a stepped energy dissipating device used for two parallel flood discharge tunnels with different heights at high flow rates or a pressurized tunnel and a curved connection cave body of a downstream flood discharge tunnel.

Background technique

In existing projects, the bottom plate of the connecting tunnel body of two parallel spillway tunnels with different heights is often designed as a smooth Wolch curve. Due to the high flow velocity at the inlet of the connecting tunnel body, the flow velocity in the connecting tunnel body and the downstream spillway tunnel after the connecting tunnel body is also very high. Large, so it is necessary to set up air entrainment protection measures. In order to achieve the purpose of energy dissipation and reduce the erosion of the downstream channel, energy dissipation facilities such as stilling basins must be installed at the outlet of the spillway tunnel or inside the spillway tunnel, but this requires a large amount of work and increases the project investment.

Although the application history of stepped energy dissipators in water conservancy projects is long, they are usually used on the straight slopes of overflow dams and spillways, and are used together with other energy dissipators to dissipate energy together. For high-velocity open-flow flood discharge tunnels, or high-velocity flood discharge tunnels with pressurized outlets, when the sudden drop and expansion type aeration facilities are installed, if the step surface is a traditional horizontal plane, the flow state of the connecting section is not good, and it is easy to generate water. At the same time, it is difficult to generate horizontal tumbling water flow on the steps, but it is easy to generate cavities and form negative pressure areas, so step energy dissipators are generally not used.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide an aeration-type curved ladder energy dissipator in the flood discharge tunnel to solve the problem of the connection between two parallel flood discharge tunnels or pressurized tunnels and downstream flood discharge tunnels with different heights. The flow rate of the spillway is high, the flow state is difficult to adjust, it is easy to cause problems such as cavitation, cavitation, and low energy dissipation rate, and it reduces the amount of work and investment.

The technical scheme of the present invention: install an aeration device at the entrance of the curved connection hole, install a stepped energy dissipator on the bottom plate of the curved connection hole, and optimize the shape of the step.

The aeration-type curved ladder energy dissipation device in the flood discharge tunnel of the present invention includes an aeration device arranged at the entrance of the curved connection tunnel body between two parallel flood discharge tunnels with different heights or a pressurized tunnel and a downstream flood discharge tunnel. Connect the ladder energy dissipator set on the floor of the cave body. The ladder energy dissipator is located behind the adjusted slope section of the curve connecting the cave floor. The stepped section is either directly connected to the floor of the downstream spillway tunnel, or connected to the floor of the downstream spillway tunnel through an anti-arc section or an adjusted horizontal section.

The mechanism of the aeration-type curved ladder energy dissipator in the flood discharge tunnel described in the present invention: the high-speed water flow from the upstream flood discharge tunnel or pressurized tunnel enters the curved connection cave body, and the aeration device arranged at the entrance of the curved connection tunnel body is opposite to the water flow side and Aeration at the bottom, adjust the slope section to adjust the contact between the water tongue and the bottom plate, effectively avoid the impact of the water tongue on the bottom plate, and at the same time provide sufficient cavity length for the aeration device; And the transition step section transitions the water flow to the horizontal step section, so that the direction of the water flow is parallel to the slope direction of the bottom plate. The main energy dissipation is in the horizontal step section. After the water flows through the horizontal step section, the energy is greatly reduced, the flow velocity is reduced, and it enters the downstream gently spillway.

The slope and length of the adjusted slope section on the floor of the curved connection cave are determined according to the flow velocity of the upstream spillway or pressurized tunnel. The greater the flow velocity, the smaller the slope and the longer the length, so as to effectively control the cavity length and Surface morphology of water flow. The length of the slope step section is also determined by the flow velocity of the upstream spillway or pressurized tunnel. The greater the flow velocity, the longer the length; the length of the horizontal step section is based on the elevation difference between the upstream spillway or pressurized tunnel and the downstream spillway The greater the elevation difference, the greater the required energy dissipation and the longer the length of the horizontal step section.

In order to better realize the purpose of the invention, the relevant geometric parameters of the ladder energy dissipator are as follows:

The step slope i _i of the slope step section = 1:20~5, the step height 0<h _i <1.0m; the step height h of the horizontal step section is greater than the step height h _i of the slope step section, and the step length l is the step height h 1 to 5 times.

The step height of the transition step section transitions from the step height h _i of the inclined step section to the step height h of the horizontal step section.

The present invention has the following beneficial effects:

1. The aeration device at the entrance of the curve-connected cave body can effectively aerate the high-speed water flow at the entrance. The aerated water flow can protect the first few steps and reduce or avoid the possibility of cavitation damage on the steps. The curve-connected cave body The ladder energy dissipator on the bottom plate can effectively transition the direction of the high-speed water flow to be parallel to the gradient of the ladder, adjust the flow state of the curved connection hole, and greatly reduce the flow rate at the outlet of the curved connection hole, so as to achieve the purpose of energy dissipation and reduce the impact on Scouring of the downstream spillway.

2. The downstream flood discharge tunnel does not need to be equipped with aerated corrosion reduction facilities, and the shape design and construction are more convenient and simple.

3. Compared with installing stilling basins and other energy-dissipating devices at the outlet of the flood discharge tunnel or in the flood discharge tunnel, the engineering quantity is reduced and the project investment is reduced.

4. The air-entrained curved ladder energy dissipator described in the present invention has a simple structure and easy shape optimization, and can be widely used in curved connection tunnels of flood discharge tunnels with different flow rates and different slopes.

Description of drawings

Fig. 1 is a kind of structural representation of aerated type curve ladder energy dissipator in the flood discharge tunnel of the present invention;

Fig. 2 is A-A sectional view of Fig. 1;

Fig. 3 is the enlarged view of the I-I section of Fig. 1;

Fig. 4 is the enlarged view of the II-II section of Fig. 1;

Fig. 5 is an enlarged view of the III-III section of Fig. 1;

Fig. 6 is an enlarged view of the IV-IV section of Fig. 1;

Fig. 7 is another structural schematic diagram of an aeration-type curved ladder energy dissipator in a flood discharge tunnel according to the present invention;

Fig. 8 is A-A sectional view of Fig. 7;

Fig. 9 is an enlarged view of the I-I section of Fig. 7;

Figure 10 is an enlarged view of the II-II section of Figure 7;

Fig. 11 is an enlarged view of the section III-III in Fig. 7 .

In the figure, 1-Pressure tunnel or upstream spillway, 2-Pressure slope, 3-Aeration device, 4-Adjustment slope section, 5-Slope step section, 6-Transition step section, 7-Horizontal step section, 8- Anti-arc section, 9-adjustment horizontal section, 10-downstream spillway, 11-water surface line, 12-bottom cavity, 13-side cavity.

Δ - drop height, i ₀ - adjust the slope of the slope, L ₁ - adjust the length of the slope, L ₂ - the length of the slope step, i _i - the slope of the slope, h _i - the height of the slope, L ₃ - the length of the transitional step, L ₄ - the length of the horizontal step, l - the step length of the horizontal step, h - the step height of the horizontal step, θ - the slope of the horizontal step, L ₅ - the length of the anti-arc segment, R - Anti-arc radius, L ₆ - Adjust the length of the horizontal section, V-curve to connect the inlet flow rate of the hole.

Detailed ways

Below in conjunction with accompanying drawing, the structure of the aerated type curved ladder energy dissipator in the flood discharge tunnel of the present invention will be further described.

Example 1

In this embodiment, the aeration-type curved ladder energy dissipator in the spillway tunnel is used for the curved connection between the upstream pressurized tunnel (empty tunnel) 1 and the downstream spillway tunnel 10 . The pressurized tunnel (empty tunnel) 1 and the downstream flood discharge tunnel 10 are parallel to each other, and the elevation difference between them is about ^28m ; Single-width flow rate q=54m ³ /sm, pressure slope 2 is set at the outlet, the section gradually changes from circular to rectangular (see Figure 3 and Figure 4), the width B ₁ of the rectangular section =2.5m, and the height H ₁ =2.25m ; The cross-section of the curve-connected cave body is shown in Figure 5, its width B ₂ =3.5m, the height of its side wall straight wall H ₂ =5.0m, and its maximum flow velocity at the inlet V=30m/s; the cross-section of the downstream flood discharge tunnel As shown in Figure 6, its width B ₃ =7.5m, and the height H ₃ of the straight wall of the side wall =8.0m.

The aeration-type curved ladder energy dissipator in the flood discharge tunnel in this embodiment has a structure as shown in Figure 1 and Figure 2. The aeration device 3 arranged at the entrance of the curved-connected cave body and the bottom plate of the curved-connected cave body Set of Ladder Energy Dissipators Composition. The aeration device 3 is a sudden expansion and sudden drop structure, and its drop height Δ=0.5m. The ladder energy dissipator is located behind the adjustment slope section 4 where the curve connects the bottom plate of the cave body. From the high position to the low position, it is the slope step section 5, the transition step section 6 and the horizontal step section 7. The horizontal step section 7 passes through the anti-arc section 8, adjustment The horizontal section 9 is in contact with the floor of the downstream spillway tunnel 10 . The relevant geometric parameters are as follows: adjust the length L ₁ of the slope section 4 = 15m, the slope i ₀ = 0.10; the length L ₂ of the slope section 5 = 34m, the number of steps is 8, and the gradient i _i = 1:10～6, Step length transitions from 5m to 3m, step height h _i =0.5m; length of transition step section 6 L ₃ =18m, number of steps is 6, step height transitions from 0.5m to 1m, step length is 3m; horizontal step The length L ₄ of section 7 = 36m, the slope θ = 1: 3, the number of steps is 12, the step height is h = 1m, the step length l = 3m; the length L ₅ of the anti-arc section 8 = 12m, and the anti-arc radius R =40m; adjust the length L ₆ of the horizontal section 9 =6m.

Experiments show that the water flow in the curve-connected cave is smooth, there is no unfavorable hydraulic phenomenon, the water flow in the stepped section is obviously aerated, the energy dissipation rate of the stepped energy dissipater is between 40% and 50%, and the outlet flow rate of the curved-connected cave is 25m/s, which greatly reduces the flow velocity of the downstream spillway.

Example 2

In this embodiment, the aeration-type curved ladder energy dissipator in the spillway tunnel is used for the curved connection between the upstream spillway tunnel (open channel) 1 and the downstream spillway tunnel 10 . The upstream flood discharge tunnel 1 and the downstream flood discharge tunnel 10 are parallel to each other, and the elevation difference between them is about 42m; the section of the upstream flood discharge tunnel 1 is shown in Figure 9, its width B ₁ =3.0m, and the height of its side wall H ₁ =5.0m, maximum flow rate Q=210m ³ /s, maximum single-width flow rate q=70m ³ /sm; the cross-section of the curved cave body is shown in Figure 10, its width B ₂ =4.0m, and its side wall is straight The height of the wall surface H ₂ =8.0m, the maximum flow velocity at the inlet V=35m/s; the cross-section of the downstream flood discharge tunnel is shown in Figure 11, its width B ₃ =7.0m, and the height of the side wall H ₃ = 7.0.

The structure of the aeration-type curved ladder energy dissipator in the flood discharge tunnel in this embodiment is shown in Figure 7 and Figure 8. The aeration device 3 arranged at the entrance of the curved connection cave body and the bottom plate of the curved connection cave body Set of Ladder Energy Dissipators Composition. The aeration device 3 is a sudden expansion and sudden drop structure, and its drop height Δ=1.0m. The ladder energy dissipator is located behind the adjustment slope section 4 where the curve connects the bottom plate of the cave body. From the high position to the low position, it is the slope step section 5, the transition step section 6 and the horizontal step section 7. The horizontal step section 7 passes through the anti-arc section 8, adjustment The horizontal section 9 is in contact with the floor of the downstream spillway tunnel 10 . The relevant geometric parameters are as follows: adjust the length L ₁ of the slope section 4 = 40m, the slope i ₀ = 0.05; the length L ₂ of the slope section 5 = 42m, the number of steps is 8, and the gradient i _i = 1:13.33～8.33, The step length transitions from 8m to 5m, the step height h _i =0.6m; the length L ₃ of the transition step section 6 =40m, the number of steps is 10, the step height transitions from 0.6m to 1.2m, and the step length is 4.0m; The length L ₄ of the horizontal step section 7=60m, the slope θ=1:3.33, the number of steps is 15, the step height is h=1.2m, and the step length l=4.0m; the length L ₅ of the anti-arc section 8=20m, Anti-arc radius R = 40m; adjust the length L ₆ of the horizontal section 9 = 15m.

Experiments show that the water flow in the curved connection cave is smooth, there is no unfavorable hydraulic phenomenon, the water flow in the step section is obviously aerated, the energy dissipation rate of the step energy dissipator is about 60%, and the outlet flow rate of the curved connection cave is 25m/s. The flow velocity of the downstream spillway is greatly reduced.

Claims (3)

1. An aeration-type curved ladder energy dissipator in a flood discharge tunnel, including a curved connection tunnel entrance between two parallel flood discharge tunnels or pressurized tunnels (1) with different heights and a downstream flood discharge tunnel (10) The aeration device (3) is characterized in that it also includes a ladder energy dissipator arranged on the bottom plate of the curved connection hole body, and the ladder energy dissipator is located behind the adjustment slope section (4) of the curve connection hole bottom plate, from a high position to At the low position, the ladder energy dissipators are successively the slope step section (5), the transition step section (6) and the horizontal step section (7). 2. The aeration-type curved ladder energy dissipator in the spillway tunnel according to claim 1, characterized in that the gradient i _i of the inclined-plane step section (5) is 1:20~5, and the height of the step is 0<h _i <1.0 m; the step height h of the horizontal step section (7) is greater than the step height h _i of the slope step section, and the step length l is 1 to 5 times the step height h. 3. The aeration-type curved ladder energy dissipator in the spillway tunnel according to claim 2, characterized in that the step height of the transition step section (6) transitions from the step height h _i of the slope step section (5) to the horizontal step The step height h of section (7).

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