CN111927676B - Draft tube using guide grid composed of rectangular guide fins as vortex suppression device - Google Patents
Draft tube using guide grid composed of rectangular guide fins as vortex suppression device Download PDFInfo
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- CN111927676B CN111927676B CN202010660757.9A CN202010660757A CN111927676B CN 111927676 B CN111927676 B CN 111927676B CN 202010660757 A CN202010660757 A CN 202010660757A CN 111927676 B CN111927676 B CN 111927676B
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- rectangular
- flow guide
- draft tube
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- small rectangular
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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 grating which is connected with the outlet of a runner of a mixed flow turbine and consists of rectangular guide vanes and is used as a draft tube of a vortex suppression device, the draft tube comprises a straight cone cylinder with a conical axial section and a through hole, the middle of the inner cavity of the straight cone cylinder is provided with the draft grating which consists of two guide vanes with rectangular cross sections, the two guide vanes are respectively an external large rectangular guide vane and an internal small rectangular guide vane, the small rectangular guide vane is positioned in the middle of the inside of the large rectangular guide vane, the large rectangular guide vane and the small rectangular guide vane are vertically arranged and have the same axial height, the upper surface and the lower surface are respectively flush, and the straight cone cylinder and the large rectangular guide vane and the small rectangular guide vane have the same central axis; when water flows out of the runner outlet and enters the draft tube, the vortex strips begin to develop towards the wall of the draft tube, and when the water flows through the diversion grid, the vortex strips are blocked and limited in the diversion grid, the eccentric vortex strips are damaged, the eccentricity of the vortex strips is reduced, partial vortex is eliminated, the strength of the vortex is reduced, and pressure pulsation is weakened.
Description
Technical Field
The invention relates to a mixed-flow water turbine, in particular to a draft tube structure connected with an outlet of a rotating wheel of the mixed-flow water turbine.
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. In a common water turbine, a draft tube is arranged at an outlet of a runner, so that water flowing out of the runner is collected and sent to a downstream river channel, and residual energy of the water flowing out of the runner 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 low internal central pressure and high peripheral pressure of the draft tube, a dead water area is formed in the central area of the draft tube, the water flow at the central part forms reverse flow in a reverse flow manner, and meanwhile, periodic eccentric motion is generated to form a regular spiral vortex belt, and the periodic swing of the vortex belt can generate periodically changed pressure at a certain fixed point of the wall of the draft tube, so that the serious pressure pulsation phenomenon is caused, the vibration of a unit is caused, and the stable operation of the water turbine is influenced. The pressure pulsation of the draft tube is solved by adopting 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 certain 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, the strength of the vortex in the tail 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. 201910406329.0 discloses a straight tapered draft tube having elliptical and regular hexagonal meshes, in which a main flow region and a dead water region are mainly partitioned by a flow dividing cylinder, and a vortex strip on the inner wall surface of the draft tube is broken by flow dividing plates of the elliptical and regular hexagonal meshes, thereby reducing pressure pulsation of the draft tube. But it has problems that: due to the structure and arrangement form of the splitter vane, the area of the overflowing section is small, the flow velocity of 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 aims to overcome the defects of the prior art and provides a draft grating consisting of rectangular guide fins as a draft tube of a vortex suppression device, which weakens pressure pulsation and keeps a water turbine to operate stably, and the rectangular guide fins with 2 length-width ratios of 4:3 are used as the draft tube of the vortex suppression device, so that the draft tube has a larger overflow area, has smaller influence on a main flow area, weakens the circulation of a dead water area, reduces the circulation of the dead water area, and weakens the strength of a vortex band.
The technical scheme adopted by the invention is as follows: the vertical cone flow guiding device comprises a vertical cone cylinder with a conical axial section, wherein a conical small end is arranged at the upper end of the vertical cone cylinder, an inlet is arranged at the conical small end, a conical large end is arranged at the lower end of the vertical cone cylinder, an outlet is arranged at the conical large end, a flow guiding grid consisting of two flow guiding fins with rectangular cross sections is arranged in the middle of an inner cavity of the vertical cone cylinder, the two flow guiding fins are respectively an external large rectangular flow guiding fin and an internal small rectangular flow guiding fin, the small rectangular flow guiding fin is positioned in the middle of the inside of the large rectangular flow guiding fin, the large rectangular flow guiding fin and the small rectangular flow guiding fin are vertically arranged and have the same axial height, the upper surface and the lower surface are respectively flush, and the vertical cone cylinder and the large rectangular flow guiding fin and the small rectangular flow guiding fin have the same central axis.
Distances are reserved between the four outer side walls of the flow guide grid and the inner wall of the straight cone, the distances between the large rectangular flow guide fins and the small rectangular flow guide fins are not in contact with each other, four corners of the large rectangular flow guide fins and four corners of the small rectangular flow guide fins are fixedly connected with each other through a horizontal short support, and four corners of the large rectangular flow guide fins are fixedly connected with the inner wall of the straight cone through a horizontal long support.
The long sides of the large rectangular guide fin and the small rectangular guide fin are parallel, the short sides of the large rectangular guide fin and the small rectangular guide fin are parallel, the large rectangular guide fin forms a large rectangular through groove, the small rectangular guide fin forms a small rectangular through groove, and the length-width ratio of the large rectangular through groove to the small rectangular through groove is 4: 3.
The invention has the beneficial effects that:
1. when the water turbine runs off the designed working condition to generate a vortex strip, the guide grid consisting of two rectangular guide fins is arranged in the draft tube, when water flows out of the outlet of the runner and enters the draft tube, the vortex strip begins to develop towards the wall of the draft tube, and when the water flows through the guide grid, the vortex strip is blocked and limited in the guide grid, the eccentric vortex strip is damaged, the eccentricity of the vortex strip is reduced, partial vortex is eliminated, the strength of the vortex is reduced, and the purpose of fundamentally weakening pressure pulsation is achieved.
2. The invention ensures that the water flow runs more stably, increases the time for the rotating wheel of the water turbine to continuously work, reduces the possibility of the resonance phenomenon of the whole hydraulic turbine set, and ensures that the whole hydraulic turbine set can run efficiently, stably and safely.
Drawings
The invention is described in further detail below with reference to the accompanying drawings and specific embodiments;
FIG. 1 is a sectional view of a draft tube of a vortex suppressing device using a flow fence formed by rectangular guide fins according to the present invention;
FIG. 2 is a top view of FIG. 1;
FIG. 3 is an enlarged sectional view taken along line A-A of FIG. 1;
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-flow guiding grid, 5-short support, 6-long support and 7-outlet.
Detailed Description
Referring to fig. 1, 2 and 3, the invention comprises a vertical straight cone 3, the axial section of the straight cone 3 is conical, the upper end of the straight cone 3 is a conical small end, the lower end of the straight cone is a conical large end, the conical small end of the upper end is an inlet 1, the conical large end of the lower end is an outlet 7, and the straight cone 3 is communicated from the inlet 1 to the outlet 7. The outer side wall of the inlet 1 is extended with a flange structure 2, the straight cone 3 and the rotating wheel outlet of the water turbine are coaxially and fixedly connected together through the flange structure 2, and the rotating wheel outlet is communicated with the straight cone 3.
The middle of the inner cavity of the straight cone 3 is provided with a flow guiding grid 4, the flow guiding grid 4 is composed of two flow guiding fins with rectangular cross sections, and the two rectangular flow guiding fins are vertically communicated to form a rectangular through groove. The two guide vanes are respectively an external large rectangular guide vane and an internal small rectangular guide vane, the internal small rectangular guide vane is positioned in the middle of the inside of the external large rectangular guide vane, namely the large rectangular guide vane wraps the small rectangular guide vane in the middle of the inside of the large rectangular guide vane, the small rectangular guide vane is positioned in the middle of a large rectangular through groove formed by the large rectangular guide vane, and the small rectangular guide vane and the large rectangular guide vane are spaced from each other and are not in contact. The two rectangular guide fins are vertically arranged, the axial heights of the two rectangular guide fins are the same, and the upper surface and the lower surface of each rectangular guide fin are flush with each other. The right cone 3 and the two rectangular guide vanes have the same central axis, and the centers of the two guide vanes are overlapped.
The lower terminal surface of two rectangle water conservancy diversion fins has certain distance from straight cone 3 lower terminal surface, and the up end also has certain distance from straight cone 3 up end, also has certain distance between four lateral walls of water conservancy diversion bars 4 and the inner wall of straight cone 3, guarantees that water conservancy diversion bars 4 hold completely in straight cone 3.
The long sides of the large rectangular guide fin and the small rectangular guide fin are parallel to each other, the short sides of the large rectangular guide fin and the small rectangular guide fin are parallel to each other, and the length-width ratio of the rectangular through groove formed by the two rectangular guide fins is 4: 3.
The length of the large rectangular through groove formed by the large rectangular guide wing pieces is twice that of the small rectangular through groove formed by the small rectangular guide wing pieces, and the width of the large rectangular through groove is twice that of the small rectangular through groove.
Four corners of the large rectangular guide fin and four corners of the small rectangular guide fin are respectively and correspondingly fixedly connected through a horizontal short support 5, and the large rectangular guide fin and the small rectangular guide fin are connected into a whole to form a guide grid 4. Four angles of big rectangle water conservancy diversion fin are respectively through the inner wall of a long support 6 fixed connection straight cone section of thick bamboo 3 of a horizontally, four long supports 6 in total, and the contained angle between two adjacent long supports 6 is 90 degrees, and four long supports 6 are with water conservancy diversion bars 4 monolithic fixings on straight cone section of thick bamboo 3.
Diameter of inlet 1D 1And the outer diameter of the runner of the water turbineDEqual, i.e. diameter of the inlet 1D 1=D. Axial height of the right cone 3L 1=（3.5～5）D 1. Diameter of the outlet 7D 3=0.78 L 1. The axial height of the flow-guiding grid 4 isL 2，L 2=（0.08～0.2）L 1. The distance from the lower end surface of the flow guide grid 4 to the upper end surface of the straight cone 3 isL 3，L 3=（4.5～6）L 2。
The length of a small rectangular through groove formed by the small rectangular guide wing pieces isL 4，L 4=0.4D 1The length of the large rectangular through groove formed by the large rectangular guide wing pieces is 2L 4. The two rectangular guide fins are equal in thickness and are botht 1，t 1=（0.06～0.07）D 1。
The flange structure 2 has an outer diameter ofD 2，D 2=2.45 D 1Axial thickness of the flange structure 2t 2=（0.2～0.28）D 1. Eight connecting holes are uniformly distributed on the flange structure 2 along the circumferential direction, and the straight cone 3 and the rotating wheel are fixed through the connecting holes. The centers of the eight connecting holes are positioned at the diameter ofD 5On the same circle of the first and second circles,D 5=2 D 1. Diameter of each connecting hole D 6=（0.17～0.19）D 1And taking a standard diameter. The thickness of the side wall of the right cone 3 ist 3=（0.25～0.4）t 2。
In the axial direction, the long support 6 and the short support 5 are both connected to the axial middle position of the guide grid 4. The long bracket 6 and the short bracket 5 are both long cylinders, and the diameters of the circular cross sections of the long cylinders are the same and are bothD 7=（0.27～0.33） L 2。
The water flow flows into the straight cone cylinder 3 from the outlet of the runner, and has a circumferential speed component when the design working condition is deviated, so that the pressure of the central area inside the straight cone cylinder 3 is low, the peripheral pressure is high, and an eccentric vortex belt is easily formed, as shown in a forming route of the vortex belt shown in fig. 4, as shown in fig. 5, the vortex belt performs eccentric motion with an eccentric distance of e, so that large pressure pulsation is generated, vibration of a unit is caused, and adverse effects are caused. The invention arranges the guide grid 4 composed of two concentric rectangular guide vanes in the straight cone 3, when the vortex belt moves to the guide grid 4 and is blocked by the rectangular guide vanes, the movement of partial eccentric vortex belt is blocked, as shown in figure 6, the eccentricity of the vortex belt movement is changed into e ', comparing with figure 5, e' < e, the vortex belt movement area is changed into the area near the central part, therefore, the pressure change value of the straight cone 3 wall is reduced, the purpose of weakening pressure pulsation is achieved, the water flow operation is more stable, the time of the water turbine runner continuously doing work is increased, the possibility of the whole water turbine set generating resonance phenomenon is reduced, the influence of the main flow area fluid is less, and the condition of low middle pressure and high pressure around in the straight cone 3 is improved due to the existence of the guide grid 4, the cavitation phenomenon is reduced, the damage of cavitation to the straight cone 3 is reduced, the whole hydraulic turbine set can run efficiently, stably and safely.
Claims (5)
1. The utility model provides an utilize water conservancy diversion bars that rectangle water conservancy diversion fin is constituteed to make draft tube of suppressing whirlpool device, includes that an axial cross-section is straight cone section of thick bamboo (3) that link up from top to bottom of toper, and its upper end is the toper tip, and toper tip department is import (1), and its lower extreme is the toper main aspects, and toper main aspects department is export (7), characterized by: the middle of the inner cavity of the straight cone cylinder (3) is provided with a flow guide grid (4) consisting of two flow guide fins with rectangular cross sections, the two flow guide fins are respectively an external large rectangular flow guide fin and an internal small rectangular flow guide fin, the small rectangular flow guide fin is positioned in the middle of the inside of the large rectangular flow guide fin, the large rectangular flow guide fin and the small rectangular flow guide fin are vertically arranged and have the same axial height, the upper surface and the lower surface are respectively flush, and the straight cone cylinder (3) and the large rectangular flow guide fin and the small rectangular flow guide fin have the same central axis;
distances are reserved between four outer side walls of the flow guide grid (4) and the inner wall of the straight cone cylinder (3), the large rectangular flow guide fins and the small rectangular flow guide fins are not in contact with each other, four corners of the large rectangular flow guide fins and four corners of the small rectangular flow guide fins are correspondingly and fixedly connected through a horizontal short support (5), and four corners of the large rectangular flow guide fins are fixedly connected with the inner wall of the straight cone cylinder (3) through a horizontal long support (6);
the long sides of the large rectangular guide fin and the small rectangular guide fin are parallel, the short sides of the large rectangular guide fin and the small rectangular guide fin are parallel, the large rectangular guide fin forms a large rectangular through groove, the small rectangular guide fin forms a small rectangular through groove, and the length-width ratio of the large rectangular through groove to the small rectangular through groove is 4: 3.
2. The draft tube of a vortex suppression device using a flow fence formed by rectangular flow guide fins as claimed in claim 1, wherein: the length of the large rectangular through groove is twice that of the small rectangular through groove, and the width of the large rectangular through groove is twice that of the small rectangular through groove.
3. The draft tube of a vortex suppression device using a flow fence formed by rectangular flow guide fins as claimed in claim 2, wherein: diameter of the inlet (1)D 1And the outer diameter of the runner of the water turbineDEqual, axial height of the straight cone cylinder (3)L 1=（3.5～5）D 1Diameter of the outlet (7)D 3=0.78 L 1Axial height of the air guide grid (4)L 2=（0.08～0.2）L 1The distance between the lower end surface of the flow guide grid (4) and the upper end surface of the straight cone cylinder (3)L 3=（4.5～6）L 2。
4. The draft tube of claim 3, wherein the draft grate comprises rectangular guide fins as a draft tube of a vortex suppression device, the draft tube comprising: the length of the small rectangular through groove formed by the small rectangular guide wing piecesL 4=0.4D 1The thickness of the large and small rectangular guide vanes are equal and are allt 1=（0.06～0.07）D 1。
5. The draft tube of claim 3, wherein the draft grate comprises rectangular guide fins as a draft tube of a vortex suppression device, the draft tube comprising: the long support (6) and the short support (5) are both connected to the axial middle position of the flow guide grid (4), the long support (6) and the short support (5) are both long cylinders, and the diameters of the circular cross sections of the long cylindersD 7=（0.27～0.33）L 2。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010660757.9A CN111927676B (en) | 2020-07-10 | 2020-07-10 | Draft tube using guide grid composed of rectangular guide fins as vortex suppression device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010660757.9A CN111927676B (en) | 2020-07-10 | 2020-07-10 | Draft tube using guide grid composed of rectangular guide fins as vortex suppression device |
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| CN111927676A CN111927676A (en) | 2020-11-13 |
| CN111927676B true CN111927676B (en) | 2022-02-15 |
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Citations (7)
| 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 |
| GB2512567A (en) * | 2013-01-23 | 2014-10-08 | Nenad Paunovic | Wind and hydro turbines turbulence control mechanism |
| 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 |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203685453U (en) * | 2013-12-30 | 2014-07-02 | 浙江理工大学 | Mixed-flow water turbine draft tube with novel separating barriers |
| CN110259622B (en) * | 2019-05-15 | 2020-09-25 | 江苏大学 | Straight-cone-shaped draft tube with elliptical and regular hexagonal grids |
-
2020
- 2020-07-10 CN CN202010660757.9A patent/CN111927676B/en active Active
Patent Citations (7)
| 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 |
| GB2512567A (en) * | 2013-01-23 | 2014-10-08 | Nenad Paunovic | Wind and hydro turbines turbulence control mechanism |
| 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 |
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