Vertical shaft aeration drainage structure

Abstract

The present invention relates to the field of vertical shaft structures of flood discharge tunnels of water conservancy and hydropower facilities, and in particular to a vertical shaft aeration drainage structure that ensures the safe operation of the vertical shaft section by aerating the vertical shaft to reduce cavitation, including a vertical shaft, wherein the vertical shaft is sequentially divided into an upper vortex chamber section, a contraction section, a middle section of the vertical shaft, and a lower section of the vertical shaft from top to bottom, wherein an air supply channel is provided between the outlet end at the bottom of the contraction section and the inlet end at the top of the middle section of the vertical shaft. Under the action of the flowing water flow, gas can enter through the air supply channel to achieve the effect of aeration, thereby ensuring the safe operation of the vertical shaft section. In addition, such a structural design can also allow the height of the vertical shaft to be increased according to the high head, without being restricted by cavitation erosion. The air supply channel design adopted has a simple aeration structure, and although it increases part of the excavation volume, it basically eliminates the risk of cavitation erosion, which is beneficial to the safety of later operation and greatly reduces the later maintenance costs. The present invention is particularly suitable for the aeration structure of the vertical shaft of the flood discharge tunnel.

Description

Technical Field

[0001] The invention relates to the field of vertical shaft structures of flood discharge tunnels of water conservancy and hydropower facilities, in particular to a vertical shaft aeration drainage structure. Background Art

[0002] With the country's demand for clean hydropower energy, a large number of high dams need to be built to generate electricity using water head. During the construction period, diversion projects will be set up to discharge river floods. After the diversion project is completed, it can be combined with permanent projects, so the hub layout is compact and more economical; therefore, through the vertical shaft flood discharge tunnel, the upper flat section and the vertical shaft section are newly built, and the lower flat section is used in combination with the diversion tunnel, which can greatly save investment. However, the vertical shaft is affected by the high water head. When the water flow in the vertical shaft section swirls from the upper part to the lower part, the water flow velocity increases along the way to form a high-speed water flow, which is prone to cavitation erosion. It is necessary to aerate the high-speed water flow in the vertical shaft section to protect the safety of the lower part of the vertical shaft section.

[0003] The following two measures are generally used to solve the cavitation problem in the shaft section of the high-head shaft spillway tunnel: 1) Raise the water level at the bottom of the shaft to reduce the high-speed water flow section to avoid cavitation, but at the same time reduce the energy dissipation rate of the shaft, fail to fully play the role of the shaft, and increase the flow velocity in the lower flat section of the shaft, increasing the difficulty of the lower flat section structure design; 2) Increase the structural strength to resist cavitation by improving the strength of the shaft itself, but according to previous engineering experience and theoretical analysis, if cavitation occurs, even steel plate linings are prone to cavitation damage after a certain period of operation, and the durability is insufficient. Under the requirement of ensuring the energy dissipation rate of the shaft, the above two measures cannot effectively solve the cavitation problem of high-head shafts. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a vertical shaft aeration and drainage structure which can ensure the safe operation of the vertical shaft section by aerating the vertical shaft to reduce cavitation.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a vertical shaft aeration drainage structure, including a vertical shaft, which is divided into an upper vortex chamber section, a contraction section, a middle section of the vertical shaft and a lower section of the vertical shaft from top to bottom, wherein an air supply channel is arranged between the outlet end at the bottom of the contraction section and the inlet end at the top of the middle section of the vertical shaft.

[0006] Furthermore, the air supplement channel is an annular air supplement channel.

[0007] Furthermore, the diameter of the inlet end at the top of the contraction section is greater than the diameter of the outlet end at the bottom of the contraction section.

[0008] Furthermore, the diameter of the outlet end at the bottom of the contraction section is smaller than the diameter of the inlet end at the top of the middle section of the shaft, and the annular air supply channel is arranged between the outlet end at the bottom of the contraction section and the inlet end at the top of the middle section of the shaft.

[0009] Furthermore, it comprises a vertical air supplement channel, one end of which is connected to the upper vortex chamber section, and the other end of which is connected to the air supplement channel.

[0010] Furthermore, the middle section of the shaft is provided with an annular air supply channel in the middle section of the shaft.

[0011] Furthermore, the vertical air supply channel is connected to the annular air supply channel in the middle section of the shaft.

[0012] Furthermore, the vertical air supply channel is arranged along the outer wall of the shaft.

[0013] Furthermore, the upper vortex chamber section is connected to the front section of the shaft.

[0014] The beneficial effects of the present invention are as follows: in actual use, since an air supply channel is provided between the outlet end at the bottom of the contraction section and the inlet end at the top of the middle section of the shaft, under the action of the flowing water, the gas can naturally enter through the air supply channel to achieve the effect of aeration, thereby ensuring the safe operation of the shaft section. In addition, such a structural design can also allow the shaft height to be increased according to the high head without being restricted by cavitation. The air supply channel design adopted has a simple aeration structure, and although it increases some excavation volume, it basically eliminates the risk of cavitation, which is beneficial to the safety of later operation and greatly reduces the later maintenance costs. The present invention is particularly suitable for the aeration structure of the shaft of the spillway tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a top view of the water flow section where the vertical shaft of the present invention is located.

[0016] Figure 2 It is a side sectional view of the structure of the present invention.

[0017] Figure 3 yes Figure 2 AA section view in.

[0018] Figure 4 yes Figure 2 BB section view in.

[0019] Figure 5 yes Figure 2 CC section view in.

[0020] Figure 6 yes Figure 2 DD section view in.

[0021] Marked in the figure are: vertical shaft 1, front section of diversion tunnel 3, diversion tunnel plugging section 31, dam curtain 4, diversion tunnel combined section 5, water flow direction 6, downstream river channel 7, water surface line in the tunnel 8, reservoir water level 10, original ground line 11, front section of vertical shaft 12, vertical air supply channel 13, annular air supply channel 14, annular air supply channel in the middle section of vertical shaft 15, upper vortex chamber section a, contraction section b, middle section of vertical shaft c, lower section of vertical shaft d, diameter of upper vortex chamber section D0, diameter of the outlet end at the bottom of the contraction section D1, diameter of the inlet end at the top of the middle section of vertical shaft D2, inner diameter of the inner ring of the annular air supply channel in the middle section of vertical shaft D3, inner diameter of the outer ring of the annular air supply channel in the middle section of vertical shaft D4, width of the annular air supply channel L1, and thickness of the lining of the contraction section L2. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings.

[0023] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 The vertical shaft aeration drainage structure shown includes a vertical shaft 1, which is divided into an upper vortex chamber section a, a contraction section b, a vertical shaft middle section c and a vertical shaft lower section d from top to bottom, wherein an air supply channel is provided between the outlet end at the bottom of the contraction section b and the inlet end at the top of the vertical shaft middle section c.

[0024] The vertical shaft 1 involved in the present invention is a well-shaped pipeline upright on the cave wall. The aeration involved refers to: setting a ridge or groove in the high-speed water flow area, separating when the water flow passes through the aeration facility, forming an aeration cavity downstream thereof, and forcing a large amount of air to be mixed into the water flow under the turbulence of the high-speed water flow, aerating the water flow to form a water-air mixture. In actual use, since an air supply channel is provided between the outlet end at the bottom of the contraction section b and the inlet end at the top of the middle section c of the vertical shaft, a cavity is formed, so that air can be transported to the air supply channel to ensure air supply, thereby achieving aeration cavitation reduction, thereby ensuring the safe operation of the vertical shaft section. The upper vortex chamber section a is connected to the front section 12 of the vertical shaft, and the water flows into the vertical shaft 1 through the front section 12 of the vertical shaft. The air supply channel can also be used as a water discharge channel outside the upper well wall to reduce the water pressure outside the well wall, effectively achieve the purpose of drainage and pressure reduction, and reduce the thickness and reinforcement of the vertical shaft structure to improve economy.

[0025] Combined with practice, such as Figure 4 , preferably, the air supplement channel is an annular air supplement channel 14. Corresponding to this structure, preferably, the diameter of the inlet end at the top of the contraction section b is larger than the diameter of the outlet end at the bottom of the contraction section b. Figure 2As shown in FIG. 1 , the contraction section b is a trumpet structure with a large top and a small bottom. Such a structure can ensure that the water flow rotates downward along the wall. The contraction section b makes the water flow rotate downward along the wall to achieve rotational energy dissipation, thereby increasing the energy dissipation rate of the shaft.

[0026] On the basis of the above structure, in order to achieve a better aeration effect, it is preferred that the diameter of the outlet end at the bottom of the contraction section b is smaller than the diameter of the inlet end at the top of the middle section c of the shaft, and the annular air supply channel 14 is provided between the outlet end at the bottom of the contraction section b and the inlet end at the top of the middle section c of the shaft. Figure 2 and Figure 4 As shown, the annular air supply channel 14 can cooperate well with the water flow out of the contraction section b to form a cavity and achieve the corresponding aeration effect.

[0027] In order to strengthen the supply of gas required during the aeration process, the following scheme may be selected: including a vertical air supply channel 13, one end of which is connected to the upper vortex chamber section a, and the other end of which is connected to the air supply channel. Air enters the vertical air supply channel 13 from the atmosphere of the upper vortex chamber section a, and then connects to the air supply channel, and finally enters the wall-detached negative pressure cavity to mix with the water body to achieve the purpose of aeration. Such a design effectively guarantees the gas required for aeration, and also guarantees the effect of aeration. Generally, the vertical air supply channel 13 is arranged along the outer wall of the shaft 1.

[0028] In order to further enhance the aeration effect, a solution may be selected in which the middle section c of the shaft is provided with an annular air supply channel 15 in the middle section of the shaft. Figure 2 and Figure 6 As shown, the formation principle of the annular air supply channel 15 in the middle section of the shaft designed here is the same as that of the annular air supply channel 14, that is, in the middle section c of the shaft, the annular air supply channel 15 is formed by the inner diameter difference between the inner diameter D3 of the inner ring of the annular air supply channel in the middle section of the shaft and the inner diameter D4 of the outer ring of the annular air supply channel in the middle section of the shaft. The annular air supply channel 15 in the middle section of the shaft can further provide gas, and together with the vertical air supply channel 13, form a "double-ring shaft aeration and drainage structure", thereby obtaining a very ideal aeration and drainage effect. Generally, as Figure 2 As shown, the vertical air supply channel 13 is connected to the annular air supply channel 15 in the middle section of the shaft.

Claims

1. A vertical shaft aeration drainage structure, comprising a vertical shaft (1), wherein the vertical shaft (1) is divided into an upper vortex chamber section (a), a contraction section (b), a middle section of the vertical shaft (c) and a lower section of the vertical shaft (d) from top to bottom, wherein: An air supply channel is provided between the outlet end at the bottom of the contraction section (b) and the inlet end at the top of the middle section (c) of the shaft. The air supply channel is an annular air supply channel (14). The diameter of the inlet end at the top of the contraction section (b) is larger than the diameter of the outlet end at the bottom of the contraction section (b). The diameter of the outlet end at the bottom of the contraction section (b) is smaller than the diameter of the inlet end at the top of the middle section (c) of the shaft. The annular air supply channel (14) is provided between the outlet end at the bottom of the contraction section (b) and the inlet end at the top of the middle section (c) of the shaft. The annular air supply channel (14) includes a vertical air supply channel (13). One end of the vertical air supply channel (13) is connected to the upper vortex chamber section (a), and the other end of the vertical air supply channel (13) is connected to the air supply channel. The middle section (c) of the vertical shaft is provided with an annular air supply channel (15) in the middle section of the vertical shaft. The vertical air supply channel (13) is connected to the annular air supply channel (15) in the middle section of the vertical shaft. The vertical air supply channel (13) is arranged along the outer wall of the vertical shaft (1). The annular air supply channel (15) in the middle section of the vertical shaft and the vertical air supply channel (13) together constitute a double-ring vertical shaft aeration and drainage structure, thereby further improving the aeration and drainage effect. The invention is characterized in that: The upper vortex chamber section (a) is connected to the front section (12) of the shaft, and water flows into the shaft (1) through the front section 12 of the shaft. The annular air supply channel (14) is used to discharge water outside the shaft wall and reduce the thickness of the shaft structure and the reinforcement.

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