CN114016474A - Aeration facility adapted to low-inflow Freund's number - Google Patents
Aeration facility adapted to low-inflow Freund's number Download PDFInfo
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- CN114016474A CN114016474A CN202111477672.8A CN202111477672A CN114016474A CN 114016474 A CN114016474 A CN 114016474A CN 202111477672 A CN202111477672 A CN 202111477672A CN 114016474 A CN114016474 A CN 114016474A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B8/00—Details of barrages or weirs ; Energy dissipating devices carried by lock or dry-dock gates
- E02B8/06—Spillways; Devices for dissipation of energy, e.g. for reducing eddies also for lock or dry-dock gates
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B1/00—Equipment or apparatus for, or methods of, general hydraulic engineering, e.g. protection of constructions against ice-strains
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B1/00—Equipment or apparatus for, or methods of, general hydraulic engineering, e.g. protection of constructions against ice-strains
- E02B1/003—Mechanically induced gas or liquid streams in seas, lakes or water-courses for forming weirs or breakwaters; making or keeping water surfaces free from ice, aerating or circulating water, e.g. screens of air-bubbles against sludge formation or salt water entry, pump-assisted water circulation
Abstract
The invention relates to an aeration facility and a water outlet building suitable for low incoming flow Freund number. The method is suitable for the field of water conservancy and hydropower engineering, is mainly used for providing sufficient aerated water flow for the water outlet structure under the condition of low Freund's number incoming flow, and prevents the water outlet structure from cavitation erosion damage. The technical scheme adopted by the invention is as follows: an aeration facility suitable for low incoming flow Freund's number is arranged on a water outlet structure and is characterized in that: the aeration facility is provided with a flip bucket and a drop bucket which are sequentially arranged along the water flow direction, the water flow forms a flip flow water tongue after passing through the flip bucket, a bottom cavity positioned below the flip flow water tongue is formed at the downstream of the drop bucket, the bottom cavity is connected with the external atmosphere through an air vent, and air is mixed into the bottom of the water flow from the bottom cavity; and turbulent parts which can make water flow turbulent so as to uniformly mix air mixed at the bottom of the water flow to the whole flow cross section are arranged on the water outlet building bottom plate corresponding to the jet area of the water lifting tongues.
Description
Technical Field
The invention relates to an aeration facility and a water outlet building suitable for low incoming flow Freund number. The method is suitable for the field of water conservancy and hydropower engineering, is mainly used for providing sufficient aerated water flow for the water outlet structure under the condition of low Freund's number incoming flow, and prevents the water outlet structure from cavitation erosion damage.
Background
The water release building releases the flood exceeding the regulation or bearing capacity of the reservoir, the river channel, the channel and the waterlogging area, and is an important hydraulic building for ensuring the safety of the hydro-junction and the hydraulic building and reducing and avoiding flood disasters. The problem of cavitation erosion caused by high-speed water flow on the outlet structure is an important problem causing the damage of the outlet structure, and a plurality of examples of the cavitation erosion damage of the outlet structure have been generated in practical engineering.
The aeration corrosion-reducing technology is simple and efficient, so that the existing water outlet structure of large-scale water conservancy and hydropower engineering is generally provided with aeration facilities. The aeration facility can mix a large amount of air into the water flow, thereby achieving the purpose of reducing and avoiding the cavitation erosion damage of the water flow.
At present, when the Freund number of an incoming flow of an aeration facility is low, the aeration capacity is insufficient, and the aeration concentration of a downstream water flow is low; in addition, backwater is easily generated in the aeration cavity, the backwater of the cavity can submerge part or the whole vent hole, so that the aeration facility reduces the aeration capacity or completely fails, the aeration facility becomes a new cavitation source, and the water outlet structure faces cavitation damage.
In order to control cavity backwater of an aeration facility under the condition of low inflow Freund number and enhance the aeration capacity, engineering measures such as U-shaped and V-shaped aeration ridges, downstream local steep slopes and the like are developed, and a certain effect of controlling cavity backwater is achieved under a certain condition. However, under the condition of low Freund's number inflow, the aeration capability of the aeration facility is still insufficient, and cavity backwater control is still one of the problems of aeration erosion reduction.
Fig. 1 is a schematic view of the downstream flow of a conventional aeration facility under the condition of low Freund's number incoming flow, the aeration capacity of the aeration facility is low under the condition of low Freund's number incoming flow, cavity backwater is easily generated in a bottom cavity, and the backwater submerges part of or even the whole bottom cavity to influence the aeration function of the aeration facility.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in response to the above problems, an aeration facility is provided that accommodates low oncoming flow Freund numbers.
The technical scheme adopted by the invention is as follows: an aeration facility suitable for low incoming flow Freund's number is arranged on a water outlet structure and is characterized in that:
the aeration facility is provided with a flip bucket and a drop bucket which are sequentially arranged along the water flow direction, the water flow forms a flip flow water tongue after passing through the flip bucket, a bottom cavity positioned below the flip flow water tongue is formed at the downstream of the drop bucket, the bottom cavity is connected with the external atmosphere through an air vent, and air is mixed into the bottom of the water flow from the bottom cavity;
and turbulent parts which can make water flow turbulent so as to uniformly mix air mixed at the bottom of the water flow to the whole flow cross section are arranged on the water outlet building bottom plate corresponding to the jet area of the water lifting tongues.
The turbulence piece is provided with a water retaining surface which can prevent cavity backwater from flowing upwards.
The turbulent piece is of a multi-stage stepped structure arranged along the water flow direction, and the step vertical face of each step in the multi-stage stepped structure is the water retaining face. Two faces of the ladder should be vertical, so that construction is convenient on one hand, and on the other hand, the top face is a horizontal plane, so that later-stage overhaul is convenient and the ladder is convenient to pass.
The multi-stage ladder structure is positioned below the floor surface of the water outlet building.
The step top A of the steps in the multi-stage step structure and the floor surface of the water outlet building are in the same plane.
The height h of the step is 0.3 m-1.0 m. The height of the step is generally 0.3-1 m, the height range refers to the step dam face of the concrete gravity dam, a good effect can be achieved in the height range, and the construction is convenient. The width is equal to the width of the water outlet structure. The length is calculated according to the longitudinal slope of the floor of the outlet structure and the height of the selected stage.
And the length L of the multi-stage step structure is calculated based on the step height h and the longitudinal slope of the bottom plate of the water outlet building.
The arrangement range of the turbulence pieces is subject to the condition that the projecting flow nappes can be shot and fall within the range of the turbulence pieces under various incoming flow conditions.
The invention has the beneficial effects that: the turbulence piece is arranged at the downstream of the aeration facility, the arrangement range is reasonable, the flow state of the turbulence piece impacted by the flow-picking nappe can be formed under various incoming flow conditions, and a good aeration effect can be obtained under the flow state.
The turbulent member adopts a multi-stage step structure, so that turbulent fluctuation of water flow is enhanced, more air is sucked into the bottom of the water flow and enters the water flow, the air is rapidly mixed to the whole flow cross section, and the step vertical surface prevents upstream flow of cavity backwater, so that the cavity backwater is reduced and avoided, and the normal aeration function of an aeration facility is ensured.
The invention has very important significance for preventing cavitation erosion of water release structures of hydraulic and hydroelectric engineering and safe operation of the engineering. The invention aims to improve the aeration capacity and reduce and avoid cavity backwater through the local step structure of the downstream bottom slope of the aeration facility. The invention has simple and easy structure and the effectiveness is tested and verified.
Drawings
Fig. 1 is a schematic view showing a structure of a conventional aeration apparatus in the prior art.
Fig. 2 is a schematic structural diagram of the embodiment.
1. Flip bucket; 2. falling the threshold; 3. a vent orifice; 4. a bottom cavity; 5. returning water from the cavity; 6. and (3) a multi-stage ladder structure.
Detailed Description
The present embodiment is an aeration facility adapted to low incoming flow Buddha number on an outlet structure, the aeration facility includes a flip bucket, a drop bucket and a turbulent member sequentially arranged on a bottom plate of the outlet structure along a water flow direction.
In the embodiment, the water flow forms the flow-deflecting water tongue after passing through the flip bucket, a bottom cavity is formed between the flow-deflecting water tongue and the bottom plate of the outlet structure at the downstream of the drop bucket, the bottom cavity is connected with the external atmosphere through the vent hole, the external atmosphere continuously conveys air to the bottom cavity, and the water tongue mixes the air in the bottom cavity with the bottom of the high-speed water flow through a strong swirling roller generated by the collision between the lower edge of the water tongue and the bottom plate.
In this embodiment, the turbulence member is a multi-stage stepped structure disposed on the floor of the outlet structure along the water flow direction, and the arrangement range of the multi-stage stepped structure is determined by the range of the turbulence member within which the projecting flow tongues can be projected under various incoming flow conditions. The multi-stage stepped structure strengthens turbulent fluctuation of water flow, so that more air is sucked into the bottom of the water flow to enter the water flow and is rapidly mixed to the whole flow cross section.
In the embodiment, the vertical surface of each step on the multi-step structure is a water retaining surface, so that the upstream flow of cavity backwater can be prevented, the cavity backwater is reduced and avoided, and the normal aeration function of the aeration facility is ensured.
In this embodiment, the multi-step structure is located below the floor surface of the outlet structure, and the top point a of each step in the multi-step structure is located in the same plane as the floor surface of the outlet structure.
The structural parameters of the present embodiment include flip height tr, drop height ts, bottom slope gradient i, length L of the multi-stage step structure, local step starting position x, and step height h. The flip bucket height, the drop bucket height and the bottom slope gradient can be designed according to the traditional aeration facility, and the multistage stepped structure is arranged at the impact bottom plate of the flip flow water tongue, so that the good aeration function of the aeration facility under the condition of low Freund number incoming flow is realized, the cavity backwater is reduced and avoided, and the safety of a water outlet building is ensured.
In this example, the height h of the step is 0.3 m-1.0 m; the length L of the multi-stage step structure is calculated based on the step height h and the longitudinal slope of the bottom plate of the water outlet building.
In the embodiment, a physical model with a 1:40 scale is designed according to the arrangement form and the structural size of a certain actual water outlet building to carry out an aeration corrosion reduction test, and compared with a traditional aeration facility under the same inflow condition, the aeration characteristic of the local step bottom slope aeration facility suitable for the low inflow Freund number is researched, and the effectiveness of the aeration facility is verified.
In model test, the width of the water outlet building is 37.5cm, the gradient of the bottom slope is 1:4, and the maximum flow rate of the test is 0.31m3A converted prototype single width flow rate of about 3137.0m2And s. The scheme 1 is a traditional aeration facility, the scheme 2 is the aeration facility of the embodiment, the flip height of the schemes 1 and 2 is 1.0cm, the drop height of the flip is 5.0cm, and the size of the vent hole is 5 multiplied by 5 cm. Scheme 2 sets up multistage stair structure in aerification facility downstream 40.0cm (x ═ 40cm), and multistage stair structure includes 4 steps, and each step height is 9.0cm, and horizontal length 36.0cm, and the total length L of step section is 1.48 m.
In this example, the test flow rates were observed to be 0.14 and 0.31m3Flow state in/s, and the aeration concentration near the wall of the bottom plate water flow is measured. Flow rates of 0.14 and 0.31m3The water flow Freund's numbers per s are 2.86 and 2.64.
As can be seen from the test results, when the flow rate is 0.14m3When the aeration facility is used for aeration, a large amount of backwater is generated in the cavity of the aeration facility in the scheme 1, the backwater depth at the vent is 2.0cm, and the aeration concentration at the bottom of the downstream water flow is lower; when the flow rate increases to 0.31m3The downstream water flow bottom aeration concentration is further reduced; the backwater depth at the vent hole is 4.0cm, and the backwater just submerges the whole vent hole. When the flow rate is 0.14m3In the case of the/s, the backwater depth of the vent hole in the scheme 2 is smaller and is 0.5 cm; when the flow rate increases to 0.31m3And/s, the backwater depth at the vent hole is 1.5cm, and compared with the traditional aeration facility, the bad flow state that the cavity backwater submerges the vent hole is obviously controlled.
Table 1 shows the downstream water bottom aeration concentration along-way distribution of schemes 1 and 2, and it can be seen from table 1 that the downstream bottom aeration concentration of the conventional aeration facility at a distance of 1.5m from the kangai is less than 1%, and the aeration concentration is low; the water flow bottom aeration concentration of the local step bottom slope aeration facility is higher than 1% within the range of 2.2m at the downstream, and the water flow bottom aeration concentration of the local step bottom slope aeration facility at the downstream is obviously increased.
TABLE 1 bottom aeration concentration in downstream aeration facility
Note: and s is the distance from the aeration concentration measuring point to the kangdu of the aeration facility.
The contrast test shows that the device can effectively reduce and avoid cavity backwater, enhance the aeration capacity of the aeration facility, increase the downstream water flow aeration concentration and ensure the normal performance of the aeration function of the aeration facility under the condition of low incoming flow Freund number.
The above is only a preferred embodiment of the invention, it should be noted that: it will be apparent to those skilled in the art that adjustments to the location or size parameters of the facilities may be made without departing from the principles of the invention, and such adjustments are to be considered within the scope of the invention. The undescribed parts of the present invention are the same as or implemented using prior art.
Claims (8)
1. An aeration facility suitable for low incoming flow Freund's number is arranged on a water outlet structure and is characterized in that:
the aeration facility is provided with a flip bucket and a drop bucket which are sequentially arranged along the water flow direction, the water flow forms a flip flow water tongue after passing through the flip bucket, a bottom cavity positioned below the flip flow water tongue is formed at the downstream of the drop bucket, the bottom cavity is connected with the external atmosphere through an air vent, and air is mixed into the bottom of the water flow from the bottom cavity;
and turbulent parts which can make water flow turbulent so as to uniformly mix air mixed at the bottom of the water flow to the whole flow cross section are arranged on the water outlet building bottom plate corresponding to the jet area of the water lifting tongues.
2. The low inflow Freund's number compliant aeration facility of claim 1, wherein: the turbulence piece is provided with a water retaining surface which can prevent cavity backwater from flowing upwards.
3. The low inflow Freund's number compliant aeration facility of claim 2, wherein: the turbulent piece is of a multi-stage stepped structure arranged along the water flow direction, and the step vertical face of each step in the multi-stage stepped structure is the water retaining face.
4. The low inflow Freund's number compliant aeration facility of claim 3, wherein: the multi-stage ladder structure is positioned below the floor surface of the water outlet building.
5. The low inflow Freund's number compliant aeration facility of claim 4, wherein: the step top A of the steps in the multi-stage step structure and the floor surface of the water outlet building are in the same plane.
6. The low inflow Freund's number compliant aeration facility according to claim 4 or 5, wherein: the height h of the step is 0.3 m-1.0 m.
7. The low inflow Freund's number compliant aeration facility according to claim 4 or 5, wherein: and the length L of the multi-stage step structure is calculated based on the step height h and the longitudinal slope of the bottom plate of the water outlet building.
8. The low inflow Freund's number compliant aeration facility of claim 1, wherein: the arrangement range of the turbulence pieces is subject to the condition that the projecting flow nappes can be shot and fall within the range of the turbulence pieces under various incoming flow conditions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111477672.8A CN114016474A (en) | 2021-12-06 | 2021-12-06 | Aeration facility adapted to low-inflow Freund's number |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111477672.8A CN114016474A (en) | 2021-12-06 | 2021-12-06 | Aeration facility adapted to low-inflow Freund's number |
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| CN114016474A true CN114016474A (en) | 2022-02-08 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4327235A1 (en) * | 1993-08-13 | 1994-01-13 | Ferdinand Diedrich | Water treatment overflow pipe assembly - has folding membrane giving flow independent of water depth and preventing sludge blockages |
| CN101089296A (en) * | 2006-06-12 | 2007-12-19 | 河海大学 | Differential aeration sluice device |
| CN101195999A (en) * | 2007-10-30 | 2008-06-11 | 四川大学 | Ladder energy dissipater with doped gas device preposed |
| CN101349047A (en) * | 2008-09-04 | 2009-01-21 | 四川大学 | Aeration type curve ladder energy dissipater in flood discharge hole |
| CN104141291A (en) * | 2014-07-23 | 2014-11-12 | 中国电建集团华东勘测设计研究院有限公司 | Toothed groove type upturned aerator |
-
2021
- 2021-12-06 CN CN202111477672.8A patent/CN114016474A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4327235A1 (en) * | 1993-08-13 | 1994-01-13 | Ferdinand Diedrich | Water treatment overflow pipe assembly - has folding membrane giving flow independent of water depth and preventing sludge blockages |
| CN101089296A (en) * | 2006-06-12 | 2007-12-19 | 河海大学 | Differential aeration sluice device |
| CN101195999A (en) * | 2007-10-30 | 2008-06-11 | 四川大学 | Ladder energy dissipater with doped gas device preposed |
| CN101349047A (en) * | 2008-09-04 | 2009-01-21 | 四川大学 | Aeration type curve ladder energy dissipater in flood discharge hole |
| CN104141291A (en) * | 2014-07-23 | 2014-11-12 | 中国电建集团华东勘测设计研究院有限公司 | Toothed groove type upturned aerator |
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