CN105587716B - A kind of cylinder flow control method of the symmetrical flexible board of two pieces of band - Google Patents
A kind of cylinder flow control method of the symmetrical flexible board of two pieces of band Download PDFInfo
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- CN105587716B CN105587716B CN201610029670.5A CN201610029670A CN105587716B CN 105587716 B CN105587716 B CN 105587716B CN 201610029670 A CN201610029670 A CN 201610029670A CN 105587716 B CN105587716 B CN 105587716B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
- F15D1/00—Influencing flow of fluids
- F15D1/002—Influencing flow of fluids by influencing the boundary layer
- F15D1/0025—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply
- F15D1/006—Influencing flow of fluids by influencing the boundary layer using passive means, i.e. without external energy supply comprising moving surfaces, wherein the surface, or at least a portion thereof is moved or deformed by the fluid flow
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Abstract
The present invention discloses a kind of cylinder flow control method of the symmetrical flexible board of two pieces of band, it is by installing two pieces of flexible boards at cylindrical cross-section circumference, given fixing flexible plate mass ratio and length, the angle between the rigidity of flexible board, flexible board articulated position is adjusted, has been reached and has been reduced cylinder and rise resistance, suppress the purpose of vortex shedding.
Description
Technical field：
The present invention relates to a kind of cylinder flow control method of the symmetrical flexible board of two pieces of band, and it belongs to hydrodynamics neck
Domain.
Background technology：
Flow around bluff bodies problem can often run into practice in engineering, and as wind streams to various buildings, river flows through bridge pier,
Design of various aircraft etc..When the fluid of certain speed flows through bluff body, have vortex shedding phenomenon in the afterbody of bluff body and occur.
Coming off for whirlpool can cause bluff body surface force asymmetry occur, if bluff body is resilient support, bluff body can vibrate.Bluff body shakes
Dynamic phenomenon is normal discovery in Practical Project field as that and can cause structure collapses in adverse conditions, or even trigger calamitous
Accident.In order to avoid the generation of these accidents, the suppression to flow around bluff bodies trailing vortex is necessary.
It is especially most commonly seen and important with peripheral flow for flow around bluff bodies problem, flow control for peripheral flow
Research and the basis for understanding other various column flow around bluff bodies.At present, the flowing control major part for cylinder is to pass through profit
Realized with other rigid bodies.In nature, the motion of flexible body in a fluid can be frequently observed.For example, wind is blown
Leaf makes it become different forms, and flag lets it flow, fish in water etc..Flexible body is introduced in flowing controls, was not both had
Outside energy exports, and flexible body can also move with the flowing of fluid.Because its good characteristic, flexible body are preliminary
Controlled applied to flowing.
It is seldom more than one to introducing but the research of most of Fluid Flow Around Blunt Body control is all to introduce single flexible body
State of a control is flowed after flexible body to be studied.So this just promotes us to bluff body after the more than one flexible body of introducing
The validity of flowing state of a control is studied.
The content of the invention：
Control method based on existing single flexible plate to peripheral flow, present invention introduces two pieces of flexible boards, further
Suppress trailing vortex, reduce liter resistance, to reach more preferable peripheral flow control effect.
The present invention adopts the following technical scheme that：A kind of cylinder flow control method of the symmetrical flexible board of two pieces of band, it includes
Following steps：
(1) for a fixed cylindrical structural, axially it is hinged two pieces of angled α's at cross-sectional circumferential
Flexible board；
(2) flexible board can deform around in the presence of flow field, and the position vector for defining flexible board is X (s, t), its
The mathematic(al) representation of deformation is：
Wherein s is the body shafting coordinate along flexible board, and t is the time, ρsIt is the linear density of flexible board, T is along soft
The tension force of property plate, KbIt is bending coefficient, FfIt is applied force vector of the flow field to flexible board；
(3) two dimensionless groups relevant with flexible board attribute are defined：Mass ratio mr, frequency compare wr, their mathematical table
It is respectively up to formula
Wherein ρ is freely to carry out current density, and L is flexible board length, fvIt is the vortex shedding frequency of single cylinder,It is the first intrinsic frequency of flexible board, KbIt is the bending coefficient of flexible board, it represents flexible board
Rigidity, compare w by adjusting frequencyr, to change the rigidity of flexible board.
Further, in the hinged place of flexible board and cylinder, using simple boundary condition, i.e.,：
For flexible board free end, following condition is utilized：
The present invention has the advantages that：The present invention installs two pieces of flexible boards at the cross-sectional circumferential of cylinder axial direction, gives
Determine fixing flexible plate mass ratio and length, adjust the angle between the rigidity of flexible board, flexible board articulated position, reach reduction circle
Post rises resistance, suppresses the purpose of vortex shedding.
Brief description of the drawings：
Fig. 1 is the cylinder schematic diagram for being hinged with two pieces of symmetrical flexible boards.
Wherein：Fig. 1 (a) is schematic three dimensional views, and Fig. 1 (b) is two-dimensional representation.
Fig. 2 is the single cylinder obtained by the present invention, is hinged with the cylinder of single flexible plate and is hinged with two pieces of symmetrical flexibilities
The comparison of the cylinder of plate ascending aorta banding in the case of different frequency ratio.
Wherein：Fig. 2 (a) is maximum lift coefficient Δ ClWith frequency than change curve, Fig. 2 (b) is average resistance coefficientWith frequency than change curve.
Embodiment：
It refer to shown in Fig. 1, the cylinder flow control method of the symmetrical flexible board of two pieces of band of the present invention, by adjusting flexible board
Rigidity and hinge angle, to determine optimal control variable.Flexible board can deform around in the presence of flow field.It is wrapped
Include following steps：
(1) for a fixed cylindrical structural, axially it is hinged two pieces of angled α's at cross-sectional circumferential
Flexible board；
(2) flexible board can deform around in the presence of flow field, and the position vector for defining flexible board is X (s, t), its
The mathematic(al) representation of deformation is：
Wherein s is the body shafting coordinate along flexible board, and t is the time, ρsIt is the linear density of flexible board, T is along soft
The tension force of property plate, KbIt is bending coefficient, FfIt is applied force vector of the flow field to flexible board；
(3) two dimensionless groups relevant with flexible board attribute are defined：Mass ratio mr, frequency compare wr, their mathematical table
It is respectively up to formula
Wherein ρ is freely to carry out current density, and L is flexible board length, fvIt is the vortex shedding frequency of single cylinder,It is the first intrinsic frequency of flexible board, KbIt is the bending coefficient of flexible board, it represents flexible board
Rigidity, compare w by adjusting frequencyr, the rigidity of flexible board can be changed.
For this invention, in the hinged place of flexible board and cylinder, using simple boundary condition, i.e.,：
For flexible board free end, following condition is utilized：
In addition, the flexible board mass ratio of the present invention is set to 1, flexible board length is equal to body diameter, wrChanged to from 0.2
1.5, consider 2 different hinge angle α (α=0 °, 90 °).
Maximum lift coefficient Δ C under different anglelAnd average resistance coefficientWith frequency than change curve such as Fig. 2 institutes
Show.Compared with the liter drag consequence of single cylinder, the ascending aorta banding in the case of flexible board has been hinged it and has been respectively less than single cylinder
Situation.That is the use of flexible board has reached preferable control effect.For 90 ° of situations, the circle under two pieces of flexible boards
The lift coefficient that post streams is respectively less than 0 ° of situation, i.e. single flexible plate.For resistance coefficient, except wrOutside=0.8 example,
The result of resistance coefficient of two pieces of flexible boards under remaining example is respectively less than the result of single flexible plate.Contrasted by numerical result
Research finds, when α is 90 °, wrFor 0.6 when, control effect is optimal.
Described above is only the preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, some improvement can also be made under the premise without departing from the principles of the invention, and these improvement also should be regarded as the present invention's
Protection domain.
Claims (2)
- A kind of 1. cylinder flow control method of the symmetrical flexible board of two pieces of band, it is characterised in that：Comprise the following steps(1) for a fixed cylindrical structural, two pieces of angled α flexibility is axially hinged at cross-sectional circumferential Plate；(2) flexible board can be deformed around in the presence of flow field, and the position vector for defining flexible board is X (s, t), and it is deformed Mathematic(al) representation be：<mrow> <msub> <mi>&rho;</mi> <mi>s</mi> </msub> <mfrac> <mrow> <msup> <mo>&part;</mo> <mn>2</mn> </msup> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <msup> <mi>t</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>-</mo> <mfrac> <mo>&part;</mo> <mrow> <mo>&part;</mo> <mi>s</mi> </mrow> </mfrac> <mrow> <mo>(</mo> <mi>T</mi> <mfrac> <mrow> <mo>&part;</mo> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <mi>s</mi> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>+</mo> <mfrac> <msup> <mo>&part;</mo> <mn>2</mn> </msup> <mrow> <mo>&part;</mo> <msup> <mi>s</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mrow> <mo>(</mo> <msub> <mi>K</mi> <mi>b</mi> </msub> <mfrac> <mrow> <msup> <mo>&part;</mo> <mn>2</mn> </msup> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <msup> <mi>s</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>=</mo> <msub> <mi>F</mi> <mi>f</mi> </msub> <mo>.</mo> </mrow>Wherein s is the body shafting coordinate along flexible board, and t is the time, ρsIt is the linear density of flexible board, T is along flexible board Tension force, KbIt is bending coefficient, FfIt is applied force vector of the flow field to flexible board；(3) two dimensionless groups relevant with flexible board attribute are defined：Mass ratio mr, frequency compare wr, their mathematic(al) representation Respectively<mrow> <msub> <mi>m</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <msub> <mi>&rho;</mi> <mi>s</mi> </msub> <mrow> <mi>&rho;</mi> <mi>L</mi> </mrow> </mfrac> <mo>,</mo> <msub> <mi>w</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>&pi;f</mi> <mi>v</mi> </msub> </mrow> <msub> <mi>w</mi> <mi>n</mi> </msub> </mfrac> </mrow>Wherein ρ is freely to carry out current density, and L is flexible board length, fvIt is the vortex shedding frequency of single cylinder,It is the first intrinsic frequency of flexible board, KbIt is the bending coefficient of flexible board, it represents flexible board Rigidity, compare w by adjusting frequencyr, to change the rigidity of flexible board.
- 2. the cylinder flow control method of the symmetrical flexible board of two pieces of band as claimed in claim 1, it is characterised in that：In the hinged place of flexible board and cylinder, using simple boundary condition, i.e.,：<mrow> <mfrac> <mrow> <msup> <mo>&part;</mo> <mn>2</mn> </msup> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <msup> <mi>s</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>=</mo> <mn>0</mn> </mrow>For flexible board free end, following condition is utilized：<mrow> <mi>T</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mfrac> <mrow> <msup> <mo>&part;</mo> <mn>2</mn> </msup> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <msup> <mi>s</mi> <mn>2</mn> </msup> </mrow> </mfrac> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mfrac> <mrow> <msup> <mo>&part;</mo> <mn>3</mn> </msup> <mi>X</mi> </mrow> <mrow> <mo>&part;</mo> <msup> <mi>s</mi> <mn>3</mn> </msup> </mrow> </mfrac> <mo>=</mo> <mn>0.</mn> </mrow>
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| CN201610029670.5A CN105587716B (en) | 2016-01-15 | 2016-01-15 | A kind of cylinder flow control method of the symmetrical flexible board of two pieces of band |
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| CN201610029670.5A CN105587716B (en) | 2016-01-15 | 2016-01-15 | A kind of cylinder flow control method of the symmetrical flexible board of two pieces of band |
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| CN105587716B true CN105587716B (en) | 2018-02-02 |
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| CN108945428B (en) * | 2018-06-08 | 2021-06-22 | 南京航空航天大学 | Flapping wing lift/thrust lifting method based on non-uniform flexibility distribution tail tip |
| CN113436596B (en) * | 2021-06-02 | 2022-07-22 | 北京航空航天大学 | Noise reduction device and determination method for inhibiting pure sound noise degree of passive body streaming |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101982661A (en) * | 2010-11-16 | 2011-03-02 | 重庆大学 | Vibration-proof circular pipe and using method thereof |
| CN103469830A (en) * | 2013-09-16 | 2013-12-25 | 水利部交通运输部国家能源局南京水利科学研究院 | Reduction method for basic wave current vibration of offshore wind power single pile |
| CN203475297U (en) * | 2013-07-03 | 2014-03-12 | 重庆工商职业学院 | Icebreaking anti-streaming combined streamline bridge pier |
| CN104790881A (en) * | 2015-02-14 | 2015-07-22 | 中国石油大学(华东) | Marine riser vortex-induced vibration abatement device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7784732B2 (en) * | 2007-01-04 | 2010-08-31 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Boundary-layer-ingesting inlet flow control system |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101982661A (en) * | 2010-11-16 | 2011-03-02 | 重庆大学 | Vibration-proof circular pipe and using method thereof |
| CN203475297U (en) * | 2013-07-03 | 2014-03-12 | 重庆工商职业学院 | Icebreaking anti-streaming combined streamline bridge pier |
| CN103469830A (en) * | 2013-09-16 | 2013-12-25 | 水利部交通运输部国家能源局南京水利科学研究院 | Reduction method for basic wave current vibration of offshore wind power single pile |
| CN104790881A (en) * | 2015-02-14 | 2015-07-22 | 中国石油大学(华东) | Marine riser vortex-induced vibration abatement device |
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