An axial-flow turbine

Abstract

This invention discloses an axial-flow turbine, relating to the field of fluid machinery technology, comprising: an inlet spiral casing; a seat ring, including an upper seat ring and a lower seat ring, respectively fixedly disposed on the upper and lower sides of the outlet of the inner edge of the inlet spiral casing, with multiple fixed guide vanes arranged circumferentially; a bottom ring, disposed inside the lower seat ring, with multiple movable guide vanes arranged circumferentially on its top; a main shaft, rotatably disposed in the middle of the bottom ring; a hub, disposed at the bottom of the main shaft, with helical blades disposed on the outer side of the hub; a tailrace pipe, disposed at the bottom of the bottom ring, supporting the turbine; an upper water tank, connected to the side wall of the inlet spiral casing via an upper water tank inlet pipe; a lower water tank, disposed below the upper water tank, connected to the tailrace pipe via a lower water tank inlet pipe; and two fish-blocking nets, respectively disposed at the connection points of the inlet spiral casing and the upper water tank inlet pipe, and the tailrace pipe and the lower water tank inlet pipe. This invention significantly reduces the pressure and shear force damage to fish passing through the turbine's flow channels, ensuring the turbine's energy harvesting efficiency.

Description

Technical Field

[0001] This invention relates to the field of fluid machinery technology, and in particular to an axial-flow water turbine. Background Technology

[0002] In water conservancy projects, dams and complex water turbines obstruct fish migration routes, severely impacting the normal life cycle of migratory fish species. Some fish species migrate upstream to spawn, but dam projects prevent gene exchange and species continuation, potentially pushing them to the brink of extinction and seriously affecting the sustainable development of local ecosystems and global biodiversity.

[0003] Currently, research on fish swimming upstream across dams is more extensive, primarily utilizing methods such as fish ladders, fish gates, and fish lifts. While methods for fish swimming downstream across dams include spillways and turbine channels, research findings on these methods are less abundant than on upstream crossings. In fact, spillways have proven ineffective and costly, so downstream crossings via turbines remain the primary approach. Furthermore, smaller fish swimming downstream through spillways inevitably enter the turbine channel due to various issues with the equipment. The complex, unnatural structure of the turbine and the unpredictable hydraulic environment can cause fatal injuries to the fish, resulting in a very high mortality rate during downstream crossings and severely impacting ecological balance and biodiversity.

[0004] The complex guide vane and blade structure inside a water turbine, as well as the rapidly changing flow characteristics of water velocity and direction, can damage fish. The survival rate of fish migrating downstream largely depends on their path through the water turbine. Potential damage to fish passing through a water turbine includes mechanical damage from impacts and scrapes, pressure damage from high or low pressure, shear force damage, and cavitation erosion damage.

[0005] Axial-flow turbines have a wide range of applications and a higher fish passage rate compared to other turbines. Optimizing the design of axial-flow turbines to be more suitable for fish passing downstream through dams has a more practical significance for environmental protection.

[0006] Although researchers have conducted in-depth studies on improving the hydraulic performance of axial-flow turbines and have also carried out some research on fish-friendly turbines, designing methods such as spillways and turbine flow channels, the results show that the effectiveness of spillways is unsatisfactory, and the economic cost is relatively high. Moreover, when some small fish pass downstream through the spillway to cross the dam, they inevitably enter the turbine flow channel due to problems with the device. The complex, unnatural structure of the turbine and the uncertain hydraulic environment can cause fatal damage to the fish, resulting in a very high mortality rate for fish crossing the dam downstream, seriously affecting ecological balance and biodiversity. Summary of the Invention

[0007] This invention provides an axial-flow turbine that can solve the problems existing in the prior art.

[0008] This invention provides an axial-flow turbine, comprising:

[0009] Water-drawing spiral shell;

[0010] The seat ring includes an upper seat ring and a lower seat ring. The upper seat ring and the lower seat ring are respectively fixedly installed on the upper side and the lower side of the water outlet on the inner edge of the water inlet volute. Multiple fixed guide vanes are provided circumferentially between the upper seat ring and the lower seat ring.

[0011] A bottom ring is disposed inside the lower ring of the seat ring, and the top of the bottom ring is provided with multiple movable guide vanes along the circumferential direction;

[0012] The main shaft is rotatably mounted in the middle of the seat ring, and its top is connected to the power generation device.

[0013] A hub is located at the bottom of the main shaft, and helical blades are provided on the outer side of the hub;

[0014] The tailrace pipe is located at the bottom of the bottom ring to support the turbine.

[0015] The upper water tank is connected to the side wall of the water inlet casing via the upper water tank inlet pipe.

[0016] The lower water tank is located below the upper water tank and is connected to the lower water tank inlet pipe and the tail water pipe. It is connected to the upper water tank and the tail water pipe respectively through two water outlet pipes.

[0017] Two fish-blocking nets are set up at the connection points of the water intake shell and the upper water tank inlet pipe, and the tailwater pipe and the lower water tank inlet pipe, respectively, to intercept fish.

[0018] Preferably, the number of helical blades is two.

[0019] Preferably, the flange-side pitch of the helical blade is 2400mm, the wrap angle is 720°, and the hub-side pitch is a gradually changing pitch, ranging from 1920mm to 2880mm.

[0020] Preferably, the spiral blade has a groove on the water inlet side, and a rubber protective strip is installed inside the groove.

[0021] Preferably, the cross-sectional shape of the helical blade is a symmetrical airfoil or an asymmetrical airfoil.

[0022] Preferably, the number of fixed guide vanes is 12, the installation angle is 30°, and the number of movable guide vanes is 24, the movable angle is 0° to 90°.

[0023] Preferably, both the fixed guide vane and the movable guide vane are selected as streamlined pointed airfoils at both ends.

[0024] Preferably, the tailwater pipe is a bent-elbow type tailwater pipe, with a single-sided diffusion angle of 10° for the straight cone section, a circular cross-section for the inlet of the bent-elbow section, a rectangular cross-section for the outlet, and a variable cross-section angle of 90°.

[0025] Preferably, the inlet pipe of the upper water tank simulates the fish passage device of an axial flow turbine, and its direction is consistent with the water flow direction inside the siphon casing.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The spiral blade of the present invention is formed by axially unfolding the spiral line and stretching it along the hub to form a spatial twisted shape distributed on the outer periphery of the hub, which optimizes the flow state of water flowing through the turbine, improves the operating efficiency of the axial flow turbine under rated conditions, and expands the head range of the high efficiency zone.

[0028] (2) The experimental device of the present invention is divided into two water tanks, an upper water tank and a lower water tank. The upper water tank collects fish that can pass through the fish passage device, and the lower water tank collects fish that pass through the turbine flow channel. The effect of the fish passage device can be tested by comparing the number of fish in the upper and lower water tanks. The fish passage performance of the axial flow turbine blades can be tested by observing the damage to the fish in the lower water tank. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0030] Figure 1 This is a cross-sectional schematic diagram of the overall structure of an axial-flow turbine according to the present invention;

[0031] Figure 2 This is a schematic front view of an axial-flow turbine according to the present invention;

[0032] Figure 3 This is a top view schematic diagram of an axial-flow turbine according to the present invention;

[0033] Figure 4 This is a schematic diagram of the rotary wheel structure of the present invention;

[0034] Figure 5 This is a magnified partial structural diagram of the blade inlet side edge of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of the helical blade of the present invention;

[0036] Figure 7 This is a schematic diagram of the structure of the double helix blade assembly of the present invention;

[0037] Figure 8 This is a cross-sectional schematic diagram of the helical blade at different positions according to the present invention;

[0038] Figure 9 This is a schematic diagram of the cross-sectional profile of the helical blade at a distance of 100cm axially from the leading edge of the hub according to the present invention;

[0039] Figure 10 This is a schematic diagram of the cross-sectional profile of the helical blade at a distance of 200 cm from the leading edge of the hub in this invention;

[0040] Figure 11 This is a schematic diagram of the cross-sectional profile of the helical blade at a distance of 300cm axially from the leading edge of the hub according to the present invention;

[0041] Figure 12 This is a schematic diagram of the cross-sectional profile of the helical blade at a distance of 400 cm from the leading edge of the hub in this invention.

[0042] In the diagram: 1-Helical blade, 2-Hub, 3-Main shaft, 4-Water intake volute, 5-Fixed guide vane, 6-Movable guide vane, 7-Seat ring, 8-Bottom ring, 9-Rubber protective strip, 10-Tailpipe, 11-Upper water tank inlet pipe, 12-Upper water tank, 13-Lower water tank inlet pipe, 14-Lower water tank, 15-Outlet pipe, 16-Fish barrier net, 17-Card slot. Detailed Implementation

[0043] 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.

[0044] Reference Figure 1-5This invention provides an axial-flow turbine, including a main shaft 3, an inlet spiral casing 4, fixed guide vanes 5, movable guide vanes 6, a seat ring 7, a bottom ring 8, a tailrace pipe 10, an upper water tank 12, and a lower water tank 14. It also includes helical blades 1 and a hub 2 connecting the main shaft 3. The top of the main shaft 3 is connected to a power generation device. There are two helical blades 1 arranged along the hub 2. The cross-sectional shape of the helical blades 1 is a symmetrical airfoil shape. The pitch on the rim side of the helical blades 1 is constant, while the pitch on the hub side is a gradually changing pitch, ranging from 0.8 to 1.2 times the pitch at the rim. A groove 17 is provided on the inlet side of the helical blades 1, and a rubber protective strip 9 is installed inside the groove 17. The seat ring 7 includes an upper seat ring and a lower seat ring, which are fixedly installed on the upper and lower sides of the water outlet on the inner edge of the intake volute 4, respectively. Multiple fixed guide vanes 5 are arranged circumferentially between the upper and lower seat rings. A bottom ring 8 is located inside the lower seat ring, and multiple movable guide vanes 6 are arranged circumferentially on the top of the bottom ring 8. The fixed guide vanes 5 are installed behind the intake volute 4 at an angle of 30°. There are 24 movable guide vanes 6 installed behind the fixed guide vanes 5, with an angle of movement from 0° to 90°. The opening is adjusted to the optimal degree according to the actual operation of the hydropower station to ensure the turbine operates in the high-efficiency range. The fixed guide vanes 5 and movable guide vanes 6 are fixed at the same width between the seat ring 7 and the bottom ring 8. The tailrace pipe 10 is installed below the hub 2 as a support for the turbine. The upper water tank 12 is connected to the upper water tank inlet pipe 11 and the water intake volute 4, and to the lower water tank 14 via the outlet pipe 15. The lower water tank 14 is connected in front of the fish barrier net 16 via the lower water tank inlet pipe 13 and the tailwater pipe 10, and is connected behind the fish barrier net 16 via the outlet pipe 15 and the tailwater pipe 10. The fish barrier net 16 is located behind the connection between the water intake volute 4 and the upper water tank inlet pipe 11, and behind the connection between the tailwater pipe 10 and the lower water tank inlet pipe 13.

[0045] In this embodiment, the straight conical section of the tailrace pipe 10 has a circular cross-section, and the single-sided diffusion angle of the conical pipe is 10°. The inlet of the elbow section of the tailrace pipe 10 has a circular cross-section, and the outlet has a rectangular cross-section with a variable cross-section angle of 90°. The diffuser section of the tailrace pipe 10 has a rectangular cross-section with a gradually increasing cross-sectional area. The inlet pipe of the upper water tank simulates the fish passage device of an axial flow turbine, and its direction is consistent with the water flow direction inside the siphon casing.

[0046] Reference Figure 6-12 The coordinates of key points on the airfoil curve of the helical blade 1 at different axial distances on the outer periphery of the hub 2 are represented as follows, where X and Y represent the spatial coordinate values ​​of key points on the airfoil curve of the helical blade 1. Parameters at a distance of 100cm axially from the leading edge of the hub 2 are shown in Table 1:

[0047] Table 1

[0048]

[0049]

[0050] The fitted equations for the two curves are as follows:

[0051] The left chord of helical blade 1: y = -2E-05x 3 -0.0049x 2 The right chord of helical blade 1 is y = 3E-05x. 3 +0.0081x 2 The parameters at a distance of +0.4373x+68.708 from the leading edge of wheel hub 2, 200cm axially, are shown in Table 2.

[0052] Table 2

[0053] Serial Number X Y Serial Number X Y 1 50.9878 -156.9243 11 82.5 -142.8942 2 40.7069 -150.8392 12 63.4907 -135.9004 3 30.0683 -143.2808 13 50.3986 -129.222 4 20.5774 -135.1756 14 39.9628 -122.5375 5 12.0745 -126.4721 15 30.5895 -115.2314 6 4.1718 -116.0702 16 21.9921 -107.1132 7 -3.1817 -105.2648 17 14.7942 -98.8881 8 -9.0239 -93.4269 18 8.7703 -90.5595 9 -13.0223 -82.3464 19 3.9459 -82.4447 10 -15.4374 -72.6275 20 0 -74.25

[0054] The fitted equations for the two curves are as follows:

[0055] The left chord of helical blade 1: y = -0.0003x 3 +0.0311x 2 -1.7547x-110.24

[0056] Right chord of helical blade 1: y = -1E-04x 3 +0.0207x 2 -1.8726x-75.018

[0057] The parameters at a distance of 300cm axially from the leading edge of hub 2 are shown in Table 3:

[0058] Table 3

[0059] Serial Number X Y Serial Number X Y 1 161.3944 34.3054 11 165 0 2 150.4564 40.4367 12 153.9928 4.109 3 138.558 45.828 13 141.7025 8.0565 4 126.3887 50.0589 14 129.9324 12.2559 5 114.2855 53.0387 15 118.6165 16.3716 6 102.214 54.8154 16 107.313 19.5574 7 89.8604 55.3897 17 94.6188 23.344 8 77.7841 54.691 18 82.8896 28.145 9 65.9777 52.7194 19 73.114 32.2517 10 55.1785 49.6829 20 60.3024 38.425

[0060] The fitted equations for the two curves are as follows:

[0061] The left chord of helical blade 1: y = 1E-06x 3 -0.0046x 2 +0.8171x+18.574

[0062] Right chord of helical blade 1: y = -2E-05x 3 +0.0065x 2 -1.1092x+85.508

[0063] The parameters at a distance of 400cm axially from the leading edge of hub 2 are shown in Table 4:

[0064] Table 4

[0065] Serial Number X Y Serial Number X Y 1 -122.6189 -110.4065 11 -142.8942 -82.5 2 -108.7519 -109.6621 12 -130.3668 -84.2351 3 -93.4629 -107.5076 13 -118.51 -85.0612 4 -77.921 -103.7024 14 -107.2502 -85.0741 5 -64.3072 -98.8042 15 -95.2652 -84.2075 6 -52.2364 -92.979 16 -83.5049 -82.3986 7 -42.8194 -87.2346 17 -71.9571 -79.5946 8 -35.2308 -81.6415 18 -60.5476 -75.6804 9 -27.9713 -75.2574 19 -48.9357 -70.3077 10 -23.3268 -70.4906 20 -38.1117 -63.7225

[0066] The fitted equations for the two curves are as follows:

[0067] The left chord of the helical blade (1): y = 3E-05x 3 +0.0104x 2 +1.4424x - 42.407

[0068] The right chord of the helical blade (1): y = 1E-05x 3 +0.0073x 2 +1.151x-29.858.

[0069] Compared to the commonly used axial-flow turbine blades, the axial-flow turbine blades of this invention significantly reduce the volume of the low-pressure and high-shear force zones in the runner chamber, as well as the minimum pressure and maximum shear force, thereby reducing the pressure and shear force damage to fish when passing over the helical blades.

[0070] The axial-flow turbine blades of this invention are large-angle blades, and rubber strips are installed at the water inlet side to reduce the probability of fish being impacted and the degree of damage after impact when passing through the turbine channel. This ensures that fish can pass through the turbine smoothly and effectively solves the problems of limited methods for fish to pass downstream over dams in the prior art, and the difficulty in balancing the performance of the turbine for fish passage and hydraulic performance.

[0071] In operation, the axial-flow turbine of this invention allows water to flow in from the inlet casing 4 and split at the inlet pipe 11 of the upper water tank. Fish blocked by the fish-blocking net 16 enter the upper water tank 12 through the inlet pipe 11. The upper water tank 12 collects fish effectively blocked by the fish-passing device, and excess water flows out through the outlet pipe 15. The water flow inside the turbine passes through the fixed guide vanes 5 and the movable guide vanes 6 in sequence, obtaining a circumferential velocity, and then impacts the helical blades 1. The helical blades 1 of the turbine transfer the gravitational potential energy and kinetic energy of the water. The rotational mechanical energy of the hub is converted into rotational mechanical energy, which in turn drives the main shaft 3 to rotate, and further drives the power generation device to generate electricity. After passing through the spiral blades 1, the water flows out of the turbine through the tailrace pipe 10. The water flow is split at the inlet pipe 13 of the lower water tank. The fish net 16 in the tailrace pipe 10 blocks the fish that are not blocked at the water intake volute 4 but pass through the turbine flow channel. The fish enter the lower water tank 14 through the inlet pipe 13. The lower water tank 14 collects the fish that have passed through the turbine flow channel. The excess water flows out through the outlet pipe 15 of the lower water tank.

[0072] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An axial-flow turbine, characterized in that, include: Water-drawing spiral shell (4); The seat ring (7) includes an upper seat ring and a lower seat ring. The upper seat ring and the lower seat ring are respectively fixedly installed on the upper and lower sides of the water outlet on the inner edge of the water inlet volute (4). Multiple fixed guide vanes (5) are provided circumferentially between the upper seat ring and the lower seat ring. A bottom ring (8) is provided on the inner side of the lower ring of the seat ring, and a plurality of movable guide vanes (6) are provided on the top of the bottom ring (8) along the circumferential direction. The main shaft (3) is rotatably set in the middle of the seat ring (7), and its top is connected to the power generation device; A hub (2) is provided at the bottom of the main shaft (3), and a helical blade (1) is provided on the outer side of the hub (2); The tailrace pipe (10) is located at the bottom of the bottom ring (8) to support the turbine. The upper water tank (12) is connected to the side wall of the water inlet pipe (11) and the water inlet volute (4); The lower water tank (14) is located below the upper water tank (12) and is connected to the lower water tank inlet pipe (13) and the tail water pipe (10) through two water outlet pipes (15) respectively. Two fish-blocking nets (16) are respectively set at the connection between the water intake shell (4) and the water inlet pipe (11) of the upper water tank and the connection between the tailwater pipe (10) and the water inlet pipe (13) of the lower water tank to intercept fish; The number of the spiral blades (1) is two; The spiral blade (1) has a flange side pitch of 2400mm and a wrap angle of 720°, and a hub side pitch that is a gradually changing pitch ranging from 1920mm to 2880mm.

2. The axial-flow turbine as described in claim 1, characterized in that, The spiral blade (1) has a groove (17) on the water inlet side, and a rubber protective strip (9) is installed inside the groove (17).

3. The axial-flow turbine as described in claim 1, characterized in that, The cross-sectional shape of the helical blade (1) is either a symmetrical airfoil or an asymmetrical airfoil.

4. An axial-flow turbine as described in claim 1, characterized in that, The number of fixed guide vanes (5) is 12, with an installation angle of 30°, and the number of movable guide vanes (6) is 24, with an activity angle of 0° to 90°.

5. An axial-flow turbine as described in claim 1, characterized in that, Both the fixed guide vane (5) and the movable guide vane (6) are selected with streamlined pointed airfoils at both ends.

6. An axial-flow turbine as described in claim 1, characterized in that, The tailwater pipe (10) is a bent-elbow type tailwater pipe. The single-sided diffusion angle of the straight cone section is 10°. The inlet of the bent-elbow section is a circular cross-section, and the outlet is a rectangular cross-section with a variable cross-section angle of 90°.

7. An axial-flow turbine as described in claim 1, characterized in that, The upper water tank inlet pipe (11) simulates the fish passage device of an axial flow turbine, and its direction is consistent with the water flow direction inside the water inlet casing (4).

Images