CN111927673A - Take central tube of grid net to do draft tube of suppressing whirlpool device - Google Patents
Take central tube of grid net to do draft tube of suppressing whirlpool device Download PDFInfo
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- CN111927673A CN111927673A CN202010660467.4A CN202010660467A CN111927673A CN 111927673 A CN111927673 A CN 111927673A CN 202010660467 A CN202010660467 A CN 202010660467A CN 111927673 A CN111927673 A CN 111927673A
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- central tube
- flat plates
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B3/00—Machines or engines of reaction type; Parts or details peculiar thereto
- F03B3/16—Stators
- F03B3/18—Stator blades; Guide conduits or vanes, e.g. adjustable
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B11/00—Parts or details not provided for in, or of interest apart from, the preceding groups, e.g. wear-protection couplings, between turbine and generator
- F03B11/04—Parts or details not provided for in, or of interest apart from, the preceding groups, e.g. wear-protection couplings, between turbine and generator for diminishing cavitation or vibration, e.g. balancing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Hydraulic Turbines (AREA)
Abstract
The invention discloses a draft tube with a grid mesh central tube as a vortex suppression device of a mixed-flow water turbine, which comprises a straight cone, wherein a cylindrical central tube is coaxially arranged in the straight cone, six flat plates which are vertically arranged are connected in the central tube, the six flat plates are divided into two groups, each group comprises three flat plates, the three flat plates in each group are arranged at intervals in parallel, the three flat plates in the first group are mutually and vertically connected with the three flat plates in the second group, the middle flat plate in each group comprises three flat plates in the diameter direction of the central tube, the other two flat plates in each group are respectively positioned at two sides of the middle flat plate in the same group, two ends of the six flat plates are fixedly connected with the inner wall of the central tube, the six flat plates divide the inner cavity of the central tube into a grid mesh structure, when water flows flow flows out of a rotating wheel outlet and enters the central tube, a vortex strip is damaged, the speed circulation is, the negative pressure at the center caused by the rotation of the water flow is reduced, so that the strength of the vortex belt is reduced, and the pressure pulsation is weakened.
Description
Technical Field
The invention relates to a mixed-flow water turbine in fluid machinery, in particular to a tail water pipe component of the mixed-flow water turbine, and particularly relates to a straight cone type tail water pipe provided with a vortex suppression device.
Background
The hydraulic turbine is a power machine capable of converting potential energy of water flow into mechanical energy, and it uses water flow as power to drive other machines to work, belonging to the turbine machinery in fluid machinery. The water turbine is provided with a draft tube at the outlet of the rotating wheel, so that the water flow flowing out of the rotating wheel is collected and sent into a downstream river channel, and the residual energy of the water flow at the outlet of the rotating wheel is recycled. When the water turbine deviates from the designed working condition, the outlet speed of the rotating wheel can generate circumferential component to cause the low internal central pressure and high peripheral pressure of the draft tube, so that a dead water area is formed in the central area of the draft tube, the water flow at the central part can form reverse flow in a reverse flow manner from top to bottom, and periodic eccentric motion is generated at the same time to form a regular spiral vortex strip. The pressure pulsation phenomenon of the draft tube is generally solved by the following measures in engineering:
1) a flow guide structure is added in the tail water pipe to eliminate circulation so as to achieve the purpose of eliminating or weakening the eccentric vortex band;
2) an air supplement device is arranged in the draft tube to destroy the vacuum of the draft tube. It should be noted that the supplementation of qi also causes some undesirable phenomena. For example, under normal operating conditions, the output of the water turbine is reduced, and sometimes the pressure pulsation behind the runner is increased;
3) the outlet structure of the runner is improved, so that pressure pulsation is weakened. However, the method is not suitable for all working conditions and has a large influence on the overall operation of the water turbine.
At present, the vortex suppression device is added in the tail water pipe, so that the strength of vortex in the water pipe can be limited, the pressure pulsation of the tail water pipe is reduced, the stability and the safety of the running of the hydraulic turbine set under the non-rated working condition are improved, the maintenance cost of the hydraulic turbine set is greatly reduced, and the whole efficiency of the hydraulic turbine is not greatly influenced. For example, chinese patent application No. 2019104063290 discloses a straight tapered draft tube having elliptical and regular hexagonal meshes, which mainly separates a main flow region from a dead water region by a flow dividing cylinder, and breaks a vortex zone of an inner wall surface of the draft tube by flow dividing plates of the elliptical and regular hexagonal meshes, thereby reducing pressure pulsation of the draft tube. However, the flow distribution sheet is close to the inner wall surface of the draft tube and has a special structure and arrangement form, so that the area of the flow cross section is small, the flow velocity of the local fluid in the main flow area is low, and backflow is easy to generate. Besides, due to the design of the embedded splitter plate, when the splitter plate and the splitter cylinder are damaged, the splitter plate is not easy to disassemble and replace.
Disclosure of Invention
The invention provides a straight cone type draft tube which is used as a vortex suppression device and has a central tube with a grid net, wherein the central tube is used for weakening pressure pulsation and keeping a water turbine to stably operate. The central pipe with the grid net is used as a vortex suppression device, so that a main flow area and a dead water area are separated, the influence on fluid in the main flow area is reduced, and the energy obtained by the dead water area is reduced.
The invention discloses a draft tube of a vortex suppression device with a central tube of a grid net, which adopts the technical scheme that: the three flat plates of the first group are mutually and vertically connected with the three flat plates of the second group, the middle flat plate of each group is in the diameter direction of the central tube, the other two flat plates of each group are respectively positioned at two sides of the middle flat plate of the same group, two ends of the six flat plates are fixedly connected with the inner wall of the central tube, and the six flat plates divide the inner cavity of the central tube into a grid net structure.
The outer diameter of the central tube is smaller than the inner diameter of the straight cone, and the outer side wall of the central tube is fixedly connected with the inner wall of the straight cone through a support.
The distance between the two flat plates in each group is equal, and the thickness of the six flat plates is the same.
The axial height of the flat plate is the same as that of the central tube, and the upper surface and the lower surface of the flat plate are flush with those of the central tube.
The invention has the beneficial effects that:
1) according to the invention, the central pipe with the grid net is arranged in the draft tube, when the water turbine deviates from the design working condition and runs and is easy to generate a vortex band, the vortex band is damaged after water flow enters the central pipe when flowing out from the outlet of the runner, the speed circulation is reduced, the rotation motion of the water flow is damaged, and the negative pressure at the center is reduced due to the rotation of the water flow, so that the strength of the vortex band is reduced, and the purpose of fundamentally weakening pressure pulsation is achieved.
2) The invention can make the water flow more stable, increase the time of the water turbine runner continuously doing work, reduce the possibility of the resonance phenomenon of the whole water turbine set, and make the whole water turbine set capable of operating efficiently, stably and safely.
Drawings
The invention is described in further detail below with reference to the drawings and the detailed description;
FIG. 1 is a front sectional view of a draft tube with a central tube of a lattice net as a vortex suppression device according to the present invention;
FIG. 2 is a top view of FIG. 1;
FIG. 3 is a cross-sectional view of a draft tube A-A;
FIG. 4 is a diagram of a draft tube vortex band formation pathway;
FIG. 5 is a draft tube pressure pulsation schematic;
FIG. 6 is a schematic diagram of draft tube pressure pulsation cancellation;
in the figure: 1-inlet, 2-flange structure, 3-straight cone, 4-central tube, 5-support, 6-outlet, 7-flat plate, 8-connecting hole.
Detailed Description
Referring to fig. 1 and 2, the draft tube of the present invention comprises a straight tapered cylinder 3, wherein the axial section of the straight tapered cylinder 3 is tapered, the upper end of the straight tapered cylinder 3 is a tapered small end, the lower end of the straight tapered cylinder 3 is a tapered large end, the tapered small end is an open inlet 1, and the tapered large end is an open outlet 6, so that the straight tapered cylinder 3 is through up and down. The periphery of the upper end inlet 1 of the straight cone barrel 3 is provided with a flange structure 2, the flange structure 2 is fixedly connected with the outlet of a rotating wheel of the water turbine and communicated with the outlet of the rotating wheel, and a draft tube is connected with the water turbine. Eight connecting holes 8 are uniformly formed in the flange structure 2 along the circumferential direction, and the draft tube is fixed through the eight connecting holes 8.
A center tube 4 is provided inside the right-angled cone 3, and the center tube 4 has a cylindrical shape with a center axis collinear with the center axis of the right-angled cone 3. The inside of the central tube 4 is connected with six vertically arranged equal-thickness flat plates 7, the six flat plates 7 are divided into two groups of three plates, the three flat plates 7 of each group are arranged in parallel at intervals, and the three flat plates 7 of the first group are mutually vertically connected with the three flat plates 7 of the second group. In each group of three flat plates 7, the middle flat plate 7 is vertically staggered and connected in the diameter direction of the central tube 4, namely, the two middle flat plates 7 in the two groups are vertically staggered and connected in the diameter direction of the central tube 4 which is vertical to each other. The other two flat plates 7 of each group are respectively positioned at two sides of one flat plate 7 in the middle of the same group. Both ends of six flat boards 7 all with the inner wall fixed connection of center tube 4, therefore, the length of a flat board 7 in the middle of every group is the longest, and two flat boards 7 of both sides will be shorter, and the perpendicular tie point of two flat boards 7 of first group both sides and a flat board 7 in the middle of the second group is located the internal diameter positive centre department of center tube 4, and the interval between two flat boards 7 of every group all equals, makes the interval of grid equal. The thickness of the six plates 7 is the same. Therefore, the six flat plates 7 divide the inner cavity of the central tube 4 into a grid-shaped structure, the middle of the grid shape is four square through holes surrounded by the flat plates 7, and the periphery of the grid shape is 12 irregular through holes surrounded by the flat plates 7 and the inner wall of the central tube 4.
The outer diameter of the central tube 4 is smaller than the inner diameter of the straight cone cylinder 3, the outer side wall of the central tube 4 is fixedly connected with the inner wall of the straight cone cylinder 3 through the support 5, and the whole central tube 4 is fixed in the straight cone cylinder 3. The total number of the brackets is 6, the brackets are uniformly arranged along the circumferential direction, and the included angle between the brackets is 60 degrees.
The central tube 4 has a certain axial height and has a certain distance from the inlet 1 of the straight cone cylinder 3, so that the central tube 4 is completely accommodated in the straight cone cylinder 3. The axial height of the flat plate 7 is the same as the axial height of the center tube 4, and the upper and lower surfaces are flush with the upper and lower surfaces of the center tube 4.
Diameter of inlet 1D 1And diameter of outlet of turbine runnerDEqual, i.e. diameter of the inlet 1D 1=D. Axial direction of the right cone 3Has a height ofL 1，L 1=（3.5～5）D 1Diameter of the outlet 6 of the right cone 3D 3=0.78 L 1. Axial height of the central tube 4L 2=（0.08～0.2）L 1. The distance between the lower end surface of the central tube 4 and the upper end surface of the straight cone 3L 3=（4.5～6）L 2。
Outer diameter of the flange structure 2D 2=2.45 D 1Axial thickness thereoft 2=（0.2～0.24）D 1. The eight connection holes 8 in the flange structure 2 are centered at a diameter ofD 5On the same circle of the first and second circles,D 5=2D 1. Diameter of the connecting hole 8D 6=（0.17～0.19）D 1. Side wall thickness of the right cone 3t 3=（0.25～0.4）t 2。
The support 5 is a long cylindrical solid body with the diameterD 7=（0.27～0.33）L 2. In the axial direction, the bracket 5 is attached to the side wall of the center tube 4 at an intermediate position.
Referring to fig. 3, the distance between two adjacent flat plates 7 in the inner cavity of the central tube 4L 4=0.22 D 1. Inner diameter of center tube 4D 4=1.1 D 1Side wall thickness of the central tube 4t 1=（0.06～0.07）D 1. The thickness of the plate 7 ist 4=0.8 t 1. The thickness of the flat plate 7 is different from the thickness of the side wall of the central tube 4.
As shown in fig. 4, when the water turbine deviates from the design condition, the water flow entering the draft tube from the outlet of the runner often has a certain velocity circulation, which causes the low central pressure and the high peripheral pressure inside the draft tube, a dead water area is formed in the central part, the water flow in the dead water area forms a reverse flow in the reverse flow upward, a spiral vortex band is easily generated, the dotted line in fig. 4 is the forming route of the spiral vortex band, and the spiral vortex band a finally reaches the vicinity of the inner wall of the draft tube from the center to the periphery. As shown in fig. 5, in the final active region of the vortex band, an eccentricity e exists between the center of the vortex band and the center of the draft tube, and the vortex band performs a periodic eccentric motion, so that a pressure change is generated at a certain fixed point of the draft tube, which causes a severe pressure pulsation phenomenon, resulting in vibration of the unit. Therefore, after the central pipe 4 with the grid net is arranged in the draft tube, when water flow enters the draft tube from the outlet of the runner, after passing through the central tube 4, the dead water zone in the central part of the draft tube of fig. 4 is separated from the main flow zone, the energy of the dead water zone is not supplemented by the main flow zone, meanwhile, the grid restrains circulation flow movement, so that the negative pressure at the center caused by the rotation of water flow is reduced, the water flow in the central part can not flow upwards reversely, thus preventing the formation of the eccentric vortex strip, after the device of the central pipe 4 is added, finally, the eccentric vortex belt only carries out eccentric motion with the eccentricity e' smaller than the eccentricity e, the pressure pulsation phenomenon of the draft tube is reduced, the running of water flow is more stable, the time of the rotating wheel of the water turbine continuously doing work is prolonged, the possibility of resonance phenomenon of the whole hydraulic turbine set is reduced, and the whole hydraulic turbine set can run efficiently, stably and safely.
Claims (7)
1. The utility model provides a take central tube of grid net to do draft tube of suppressing whirlpool device, includes a straight cone section of thick bamboo (3), and the axial cross-section of straight cone section of thick bamboo (3) is the toper, and its upper end is toper tip and is open import (1), and its lower extreme is toper main aspects and is open export (6), characterized by: the inner part of the right cone cylinder (3) is coaxially and concentrically provided with a cylindrical central tube (4), the inner part of the central tube (4) is connected with six flat plates (7) which are vertically arranged, the six flat plates (7) are divided into two groups, each group comprises three flat plates (7), the three flat plates (7) of each group are arranged at intervals and in parallel, the three flat plates (7) of the first group are mutually and vertically connected with the three flat plates (7) of the second group, the middle flat plate (7) of each group of the three flat plates (7) is arranged in the diameter direction of the central tube (4), the other two flat plates (7) of each group are respectively arranged at two sides of the middle flat plate (7) of the same group, two ends of the six flat plates (7) are fixedly connected with the inner wall of the central tube (4), and the inner cavity of the central tube (4) is divided into a grid network structure.
2. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 1, wherein: the outer diameter of the central tube (4) is smaller than the inner diameter of the straight cone cylinder (3), and the outer side wall of the central tube (4) is fixedly connected with the inner wall of the straight cone cylinder (3) through a support (5).
3. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 1, wherein: the distance between the two flat plates (7) in each group is equal, and the thicknesses of the six flat plates (7) are equal.
4. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 1, wherein: the axial height of the flat plate (7) is the same as that of the central tube (4), and the upper surface and the lower surface of the flat plate are flush with those of the central tube (4).
5. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 1, wherein: axial height of the right cone (3)L 1=（3.5～5）D 1，D 1Is the diameter of the inlet (1) and the axial height of the central tube (4)L 2=（0.08～0.2）L 1The distance between the lower end surface of the central tube (4) and the upper end surface of the straight cone cylinder (3)L 3=（4.5～6）L 2。
6. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 1, wherein: the distance between two adjacent flat plates (7)L 4=0.22 D 1，D 1Is the diameter of the inlet (1) and the inner diameter of the central tube (4)D 4=1.1 D 1Side wall thickness of the central tube (4)t 1=（0.06～0.07）D 1The thickness of the flat plate (7) ist 4=0.8 t 1。
7. The draft tube of a central tube with a lattice grid as a vortex suppression device as claimed in claim 2, wherein: the brackets (5) are long cylindrical solids, the number of the brackets (5) is 6, the brackets are uniformly arranged along the circumferential direction, and the diameter of each bracket (5)D 7=（0.27～0.33）L 2，L 2Is the axial height of the central tube (4), and in the axial direction, the bracket (5) is connected to the middle position of the side wall of the central tube (4).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010660467.4A CN111927673A (en) | 2020-07-10 | 2020-07-10 | Take central tube of grid net to do draft tube of suppressing whirlpool device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010660467.4A CN111927673A (en) | 2020-07-10 | 2020-07-10 | Take central tube of grid net to do draft tube of suppressing whirlpool device |
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| Publication Number | Publication Date |
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| CN111927673A true CN111927673A (en) | 2020-11-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010660467.4A Pending CN111927673A (en) | 2020-07-10 | 2020-07-10 | Take central tube of grid net to do draft tube of suppressing whirlpool device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114526392A (en) * | 2022-02-10 | 2022-05-24 | 国网福建省电力有限公司电力科学研究院 | Vortex band device is eliminated in mixing of draft tube |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3292901A (en) * | 1965-03-04 | 1966-12-20 | Newport News S & D Co | Turbine apparatus |
| CN2100503U (en) * | 1991-07-20 | 1992-04-01 | 东方电机厂 | Vane flow-stabilizing device of turbines |
| JP2007120461A (en) * | 2005-10-31 | 2007-05-17 | Toshiba Corp | Vertical shaft valve type hydraulic power generation equipment |
| CN103982361A (en) * | 2014-06-03 | 2014-08-13 | 中山市创想模型设计有限公司 | Draft tube for water turbine |
| CN106825657A (en) * | 2017-02-28 | 2017-06-13 | 哈尔滨善思科技有限责任公司 | A kind of method that 4 holes are made a call to based on the inclined operating mode hydraulic turbine draft cone of big flow |
| CN110285005A (en) * | 2019-05-15 | 2019-09-27 | 江苏大学 | A kind of turbine draft tube with round and oval grid |
-
2020
- 2020-07-10 CN CN202010660467.4A patent/CN111927673A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3292901A (en) * | 1965-03-04 | 1966-12-20 | Newport News S & D Co | Turbine apparatus |
| CN2100503U (en) * | 1991-07-20 | 1992-04-01 | 东方电机厂 | Vane flow-stabilizing device of turbines |
| JP2007120461A (en) * | 2005-10-31 | 2007-05-17 | Toshiba Corp | Vertical shaft valve type hydraulic power generation equipment |
| CN103982361A (en) * | 2014-06-03 | 2014-08-13 | 中山市创想模型设计有限公司 | Draft tube for water turbine |
| CN106825657A (en) * | 2017-02-28 | 2017-06-13 | 哈尔滨善思科技有限责任公司 | A kind of method that 4 holes are made a call to based on the inclined operating mode hydraulic turbine draft cone of big flow |
| CN110285005A (en) * | 2019-05-15 | 2019-09-27 | 江苏大学 | A kind of turbine draft tube with round and oval grid |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114526392A (en) * | 2022-02-10 | 2022-05-24 | 国网福建省电力有限公司电力科学研究院 | Vortex band device is eliminated in mixing of draft tube |
| CN114526392B (en) * | 2022-02-10 | 2023-09-22 | 国网福建省电力有限公司电力科学研究院 | Vortex band eliminating device for mixing of draft tube |
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Application publication date: 20201113 |