A flow guiding structure

Abstract

The application discloses a flow guide structure and relates to the field of hydroelectric generation. The flow guide structure comprises a plurality of flow guide plates arranged side by side in sequence, the upper and lower ends of each flow guide plate are used for being respectively mounted on the top and the bottom of a tunnel, the starting section of each flow guide plate is located inside a plane turning section, the terminal section of each flow guide plate is located inside a straight section downstream of the plane turning section, and the mounting angle of at least one flow guide plate is deviated towards the inside of the plane turning section, so as to guide the water flow close to the outside of the plane turning section inside the tunnel to the center and the inside of the tunnel. The flow guide structure solves the problem of uneven distribution of the flow of the inlet / outlet of the downstream of the plane turning section, has high applicability, and saves the investment cost of a power station.

Description

Technical Field

[0001] This invention relates to the field of hydropower generation, and in particular to a flow guiding structure. Background Technology

[0002] Among various energy storage methods, pumped storage power stations have become an important form of large-scale renewable energy development due to their advantages such as peak shaving, frequency regulation, and black start. The inlet / outlet, as a fundamental structure in a pumped storage power station system, is a key component for achieving water flow control and hydropower utilization. It is often arranged as a side-type inlet / outlet. The inlet / outlet is generally divided into three channels by two diversion piers or four channels by three diversion piers. The diversion ratio of each channel is one of the important indicators for evaluating the internal hydraulic characteristics of the inlet / outlet. According to design specifications, the flow non-uniformity between adjacent side and central channels should not exceed 10%. The inlet / outlet is connected to the generator unit through a pressurized water conveyance tunnel; therefore, the flow pattern inside the pressurized tunnel has a significant impact on the outflow from the inlet / outlet.

[0003] In the design of pumped storage power stations, bends in pressurized water conveyance tunnels should generally be avoided, or bends should be located far from the inlet / outlet (more than 30-40 times the tunnel diameter) to reduce the adverse effects of bends on the outflow. However, due to limitations imposed by topography and geology, the arrangement of pressurized water conveyance tunnels in actual engineering projects inevitably involves planar bends. When the planar bend of the water conveyance tunnel is close to the inlet / outlet, the flow deviation phenomenon at the bend will directly affect the flow distribution at the inlet / outlet under the outflow conditions, leading to uneven flow distribution at each orifice. Furthermore, current research on side-mounted inlets / outlets focuses on optimizing the inlet / outlet's own body shape parameters, rarely considering the impact of the planar bend on the hydraulic characteristics of the inlet / outlet, especially when the downstream straight section of the planar bend is of limited length (less than 10 times the tunnel diameter). Summary of the Invention

[0004] To address the above technical problems, this invention provides a flow guiding structure that solves the problem of uneven flow distribution at the downstream inlet / outlet of a planar bend section. It has strong applicability and saves on power plant investment costs.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a flow guiding structure, comprising a plurality of flow guiding plates arranged in parallel in sequence. The upper and lower ends of each flow guiding plate are respectively used to install on the top and bottom of a tunnel. The starting cross-section of each flow guiding plate is located inside the planar bend section, and the ending cross-section of each flow guiding plate is located inside the straight section downstream of the planar bend section. The installation angle of at least one flow guiding plate is biased towards the inner side of the planar bend section, for guiding the water flow inside the tunnel near the outer side of the planar bend section to the center and inner side of the tunnel.

[0007] Optionally, the installation angle of the guide plate is the angle between the axis of the guide plate and the line connecting the center of the starting section and the ending section of the guide plate. The installation angle of each guide plate is in the range of 0° to 20°, and at least one guide plate has an installation angle greater than 0°.

[0008] Optionally, the installation angle of each of the deflectors is biased towards the inside of the planar turning section.

[0009] Optionally, all of the aforementioned deflectors are installed at the same angle.

[0010] Optionally, the starting section of each of the guide vanes is located on the same radial section of the planar turning segment, and the ending section of each of the guide vanes is located on the cross section of the straight segment downstream of the planar turning segment.

[0011] Optionally, the angle between the starting section of each of the guide vanes and the exit section of the planar turning segment is in the range of 3° to 5°.

[0012] Optionally, the distance between the end section of each of the guide vanes and the outlet section of the planar turning section is in the range of 0.1 to 0.3 times the diameter of the planar turning section.

[0013] Optionally, the distance between each of the guide vanes and the inner wall of the planar turning section at the initial cross-section is L. i The following formula is used for calculation:

[0014]

[0015] In the formula, i is the number of the guide vane, numbered sequentially from the inside to the outside of the planar turning section, 1≤i≤n, n is the number of guide vanes, and D is the diameter of the opening in the planar turning section. θ is the central angle corresponding to the arc between adjacent guide plates.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] The flow guiding structure of this invention includes multiple guide plates arranged side by side in sequence. The starting section of each guide plate is located inside the planar bend section, and the ending section of each guide plate is located inside the straight section downstream of the planar bend section. At least one guide plate is installed at an angle biased towards the inside of the planar bend section. This is used to guide the water flow inside the tunnel near the outside of the planar bend section to the center and inside of the tunnel, thereby improving the uneven flow velocity distribution inside the tunnel and solving the problem of uneven flow distribution at the inlet / outlet downstream of the planar bend section. In other words, it solves the flow deviation problem caused by the planar bend section at its source. This flow guiding structure is not only simple in structure, eliminating the need to adjust complex side-mounted inlet / outlet structures, but also achieves the goal of uniform flow distribution at the inlet / outlet under different operating conditions. Moreover, it is highly applicable, breaking through the spatial constraint that the planar bend section must be located 30 to 40 times the tunnel diameter away from the inlet / outlet, which can greatly save power plant investment costs. Compared with existing technologies, the flow guiding structure of this invention has the advantages of simplicity, economy, and strong adaptability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the installation of the flow guiding structure provided by the present invention;

[0020] Figure 2 A schematic diagram of the flow guiding structure provided by the present invention;

[0021] Figure 3 This is a schematic diagram of the starting and ending sections of the guide plate in the flow guiding structure provided by the present invention;

[0022] Figure 4 This is a schematic diagram of the installation of the guide plate in the flow guiding structure provided by the present invention;

[0023] Figure 5 for Figure 4 A magnified view of a section at point A in the middle;

[0024] Figure 6 This is a schematic diagram of the central angle corresponding to the arc between adjacent guide plates in the flow guiding structure provided by the present invention;

[0025] Figure 7 A simulation diagram of traffic allocation in the existing technology's original scheme;

[0026] Figure 8 This is a simulation diagram of flow distribution after adopting the flow guiding structure provided by the present invention.

[0027] Explanation of reference numerals in the attached drawings: 100, flow guiding structure; 1, flow guide plate; 2, planar turning section; 3, straight section; 4, inlet / outlet; 5, reservoir area; 6, water diversion tunnel; 7, starting section; 8, ending section; 9, outlet section; 10, radial section; 11, starting section of inlet / outlet diffuser section. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The purpose of this invention is to provide a flow guiding structure that solves the problem of uneven flow distribution at the downstream inlet / outlet of a planar bend section. It has strong applicability and saves on power plant investment costs.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figures 1-6 As shown, the design concept in this embodiment is to address the impact of the flow deviation effect of the planar bend section 2 on the flow distribution at the inlet / outlet 4 from the source. A three-dimensional simulation method was used to analyze the motion law of the water flow inside the planar bend section 2 and to study the influence mechanism of the planar bend section 2 on the flow distribution at the inlet / outlet 4. The results show that after the water flows through the planar bend section 2, under the action of centrifugal force, the velocity core area deviates to the outside of the bend, causing uneven velocity distribution at the initial cross-section 11 of the inlet / outlet diffuser section. Ultimately, this results in a larger flow rate in the two channels near the outside of the planar bend section 2 and a smaller flow rate in the two channels near the inside of the planar bend section 2 at the inlet / outlet 4.

[0032] Based on the internal water flow characteristics of the planar turning section 2 and its influence mechanism on the flow distribution of the inlet / outlet 4, this embodiment proposes a flow guiding structure 100 for adjusting the water flow. The flow guiding structure 100 is arranged near the outlet of the planar turning section 2. The purpose is to adjust the high-speed water flow inside the tunnel that is close to the outside of the planar turning section 2 to the center and inner area of ​​the tunnel, thereby reducing the adverse effect of the bend flow deviation phenomenon on the velocity distribution of the initial section 11 of the inlet / outlet diffusion section.

[0033] Specifically, the flow guiding structure 100 in this embodiment includes a plurality of flow guiding plates 1 arranged in parallel. The upper and lower ends of each flow guiding plate 1 are respectively installed at the top and bottom of the tunnel. The starting section 7 of each flow guiding plate 1 is located inside the plane turning section 2, and the ending section 8 of each flow guiding plate 1 is located inside the straight section 3 downstream of the plane turning section 2. The installation angle of at least one flow guiding plate 1 is biased towards the inner side of the plane turning section 2, which is used to guide the water flow inside the tunnel near the outer side of the plane turning section 2 to the center and inner side of the tunnel.

[0034] The flow guiding structure 100 can guide the main flow near the outer side of the planar bend section 2 to the inner side of the tunnel, so that the main flow with higher velocity will collide and mix with the low-velocity water flow inside the tunnel, thereby adjusting the main flow to the central area of ​​the tunnel, thereby improving the uneven flow velocity distribution inside the tunnel, and thus solving the problem of uneven flow distribution at the downstream inlet / outlet 4 of the planar bend section 2.

[0035] In this embodiment, the dimensions of the flow guiding structure 100 are determined by the position of the starting section 7, the position of the ending section 8, and the installation angle of the flow guiding plate 1.

[0036] Specifically, the installation angle α of the guide plate 1 is the angle between the axis of the guide plate 1 and the line connecting the center of the starting section 7 and the ending section 8 of the guide plate 1. The value range of the installation angle α of each guide plate 1 is 0° to 20°, and the installation angle of at least one guide plate 1 is greater than 0°.

[0037] Specifically, the installation angle of each guide vane 1 is biased towards the inside of the planar turning section 2, that is, in this embodiment, the installation angle of each guide vane 1 is greater than 0°.

[0038] In this specific embodiment, the installation angle of each guide vane 1 is the same. Specifically, the installation angle of each guide vane 1 is 5°.

[0039] Specifically, the starting section 7 of each guide vane 1 is located on the same radial section 10 of the planar turning section 2, and the ending section 8 of each guide vane 1 is located on the cross section of the straight section 3 downstream of the planar turning section 2.

[0040] The angle β between the starting section 7 of each guide vane 1 and the exit section 9 of the planar turning section 2 ranges from 3° to 5°.

[0041] The distance between the end section 8 of each guide plate 1 and the outlet section 9 of the planar turning section 2 is 0.1 to 0.3 times the diameter of the tunnel of the planar turning section 2.

[0042] In this embodiment, the distance between each guide vane 1 and the inner wall of the planar turning section 2 on the initial section 7 is L. i The following formula is used for calculation:

[0043]

[0044] In the formula, i is the number of the guide vane 1, numbered sequentially from the inside to the outside of the planar turning section 2, 1≤i≤n, n is the number of guide vanes 1, and D is the diameter of the tunnel in the planar turning section 2. θ is the central angle corresponding to the arc between adjacent guide vanes 1.

[0045] In this embodiment, the diameter of the tunnel in the planar turning section 2 is the same as the diameter of the tunnel in the straight section 3 downstream of the planar turning section 2.

[0046] In this embodiment, the number n of the guide plates 1 ranges from 2 to 7. Each guide plate 1 has a different length, and its installation angle is related to the direction of water flow inside the tunnel. That is, the installation angle of each guide plate 1 is set according to the direction of water flow inside the tunnel.

[0047] In this specific embodiment, the inlet / outlet 4 is connected to the planar turning section 2. Due to space constraints, the length of the straight section 3 between the planar turning section 2 and the inlet / outlet 4 is only 6 times the diameter of the tunnel of the straight section 3. The end of the inlet / outlet 4 away from the straight section 3 is connected to the reservoir area 5, and the end of the planar turning section 2 away from the straight section 3 is connected to the water diversion tunnel 6. Under the action of centrifugal force, a flow deviation phenomenon occurs inside the planar turning section 2, with a higher flow velocity on the outside and a lower flow velocity on the inside, resulting in uneven flow distribution in each channel of the inlet / outlet 4. To address this, this embodiment proposes a flow guiding structure 100, which includes five flow guiding plates 1 arranged side by side in sequence. The five flow guiding plates 1 are, from the inside to the outside of the planar turning section 2, the first flow guiding plate, the second flow guiding plate, the third flow guiding plate, the fourth flow guiding plate, and the fifth flow guiding plate.

[0048] In this embodiment, the angle β between the starting section 7 of each guide vane 1 and the outlet section 9 of the planar turning section 2 is 3.4°. The distance between the ending section 8 of each guide vane 1 and the outlet section 9 of the planar turning section 2 is 0.13 times the diameter of the tunnel of the planar turning section 2.

[0049] According to formula (1) in this embodiment, when n = 5,

[0050] The distances of the first guide vane, the second guide vane, and the third guide vane from the inner wall of the planar turning section 2 are specified by formula [formula missing]. The calculations yielded L1 = 0.07D, L2 = 0.25D, and L3 = 0.50D.

[0051] The distances between the fourth and fifth guide vanes and the inner wall of the planar turning section 2 are calculated using the formula... The calculations yielded L4 = 0.75D and L5 = 0.93D.

[0052] As can be seen, the distances between the first guide vane, the second guide vane, the third guide vane, the fourth guide vane, and the fifth guide vane on the starting section 7 and the inner wall of the planar turning section 2 are 0.07D, 0.25D, 0.50D, 0.75D, and 0.93D, respectively.

[0053] For the aforementioned pumped storage power station, numerical simulation was used to study the hydraulic characteristics of the inlet / outlet 4 in this embodiment and the original scheme. The diffuser section of the inlet / outlet of this power station is divided into four channels by three diversion piers. Channels one and two of the diffuser section are located near the inner side of the planar bend section 2, while channels three and four are located near the outer side of the planar bend section 2. The flow distribution of inlet / outlet 4 under different operating conditions in this embodiment compared to the original scheme is shown in Table 1.

[0054] Table 1 Comparison of inlet / outlet flow distribution under different operating conditions between this embodiment and the original scheme.

[0055]

[0056] It is evident that, under power generation conditions, the flow distribution percentages of the inlet / outlet 4 holes 1 to 4 in the original scheme are 18.84%, 16.37%, 30.32%, and 34.47%, respectively, with a difference of 18.10% between the flow distribution percentages of each hole, failing to meet the specification requirement that the flow distribution difference between each channel should not exceed 10%. This is because, under power generation conditions, inlet / outlet 4 is located downstream of the planar bend section 2. When water flows through the planar bend section 2 and then into inlet / outlet 4, due to the flow deviation phenomenon of the planar bend section 2, the velocity distribution of the water flow at the initial cross-section 11 of the diffuser section of the inlet / outlet is uneven, i.e., the velocity is higher on the outside of the planar bend section 2 and lower on the inside. Figure 7 As shown, the flow rate of the two orifices (three-hole and four-hole) near the outer side of the plane turning section 2 is significantly greater than that of the two orifices (one-hole and two-hole) near the inner side of the plane turning section 2.

[0057] In contrast, this embodiment significantly reduces the flow deviation phenomenon caused by the planar turning section 2, resulting in a more uniform water flow distribution at the initial cross-section 11 of the inlet / outlet diffuser section, such as... Figure 8 As shown, the flow distribution percentages of inlet / outlet 4 (holes 1-4) are 24.91%, 26.10%, 23.93%, and 25.06%, respectively. The flow distribution among the holes is more uniform, with a difference of only 2.17%, meeting the specification requirement that the flow distribution difference between each channel should not exceed 10%. This solves the problem of uneven flow distribution at inlet / outlet 4 caused by the flow deviation phenomenon in the planar bend section 2. Under pumping conditions, inlet / outlet 4 is located upstream of the planar bend section 2 and is less affected by it. Both this embodiment and the original scheme meet the specification requirements for flow distribution at inlet / outlet 4.

[0058] Therefore, this embodiment proposes a design method for arranging a flow guiding structure 100 near the outlet of the planar turning section 2 based on the internal flow characteristics of the planar turning section 2 and the flow distribution law of the inlet / outlet 4. It also provides a calculation method for the distribution law of the flow guiding structure 100 at the initial cross-section 7 and clarifies the requirements for the installation angle of the guide plate 1, thus fundamentally solving the flow deviation problem caused by the planar turning section 2. Not only is the structure simple, eliminating the need to adjust complex side-type inlet / outlet structures, but it also achieves the goal of uniform flow distribution at the inlet / outlet 4 under different operating conditions. Furthermore, it is highly applicable, overcoming the spatial constraint that the planar turning section 2 must be located 30 to 40 times the diameter of the inlet / outlet, thus significantly saving power plant investment costs. Compared to existing technologies, the flow guiding structure 100 in this embodiment has the advantages of simplicity, economy, and strong adaptability.

[0059] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A flow guiding structure, characterized in that, The system includes multiple guide vanes arranged side-by-side in sequence. The upper and lower ends of each guide vane are respectively installed at the top and bottom of the tunnel. The starting cross-section of each guide vane is located inside the planar bend section, and the ending cross-section of each guide vane is located inside the straight section downstream of the planar bend section. At least one guide vane is installed at an angle biased towards the inside of the planar bend section, used to guide the water flow inside the tunnel near the outside of the planar bend section to the center and inside of the tunnel. The starting cross-section of each guide vane is on the same radial cross-section of the planar bend section, and the ending cross-section of each guide vane is on the cross-section of the straight section downstream of the planar bend section. The distance between each of the guide vanes and the inner wall of the planar turning section on the initial cross-section is... L i The following formula is used for calculation: In the formula, i The guide vanes are numbered sequentially from the inside to the outside of the planar turning section, 1 ≤ i ≤ n , n The number of the guide vanes. D The diameter of the hole in the planar turning section. , θ The central angle is the arc between adjacent guide plates.

2. The flow guiding structure according to claim 1, characterized in that, The installation angle of the guide plate is the angle between the axis of the guide plate and the line connecting the center of the starting section and the end section of the guide plate. The installation angle of each guide plate is in the range of 0° to 20°, and at least one guide plate has an installation angle greater than 0°.

3. The flow guiding structure according to claim 1, characterized in that, The installation angle of each of the aforementioned guide vanes is biased towards the inside of the planar turning section.

4. The flow guiding structure according to claim 3, characterized in that, The installation angles of all the aforementioned guide vanes are the same.

5. The flow guiding structure according to claim 1, characterized in that, The angle between the starting section of each guide vane and the exit section of the planar turning segment is in the range of 3° to 5°.

6. The flow guiding structure according to claim 1, characterized in that, The distance between the end section of each of the guide vanes and the outlet section of the planar turning section is 0.1 to 0.3 times the diameter of the planar turning section.

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