CN112810800B - Laminar flow separation control method based on local vibration of wing surface - Google Patents
Laminar flow separation control method based on local vibration of wing surface Download PDFInfo
- Publication number
- CN112810800B CN112810800B CN202110113589.6A CN202110113589A CN112810800B CN 112810800 B CN112810800 B CN 112810800B CN 202110113589 A CN202110113589 A CN 202110113589A CN 112810800 B CN112810800 B CN 112810800B
- Authority
- CN
- China
- Prior art keywords
- airfoil
- vibration
- length direction
- laminar flow
- flexible structure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/36—Structures adapted to reduce effects of aerodynamic or other external heating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C23/00—Influencing air flow over aircraft surfaces, not otherwise provided for
- B64C23/04—Influencing air flow over aircraft surfaces, not otherwise provided for by generating shock waves
-
- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a laminar flow separation control method based on local vibration of the surface of a wing, and belongs to the technical field of flow control of aircrafts. According to the method, a flexible structure and a driving mechanism for driving the flexible structure to vibrate are arranged on a part of the surface of the wing section, the flexible structure vibrates reciprocally around a balance position under the action of the driving mechanism or external air flow, and the displacement of one point of the surface of the wing section in a vibration area is determined by deformation quantity in the length direction of the wing section and the distribution rule of the deformation quantity along the chord length direction of the wing section. The invention can simplify the structure of the control system, reduce the volume and obtain good laminar flow separation control effect.
Description
Technical Field
The invention belongs to the technical field of aircraft flow control, and particularly relates to a laminar flow separation control method based on local vibration of the surface of a wing.
Background
In aircrafts such as microminiature unmanned aerial vehicles and high-altitude long-endurance unmanned aerial vehicles, which have been actively developed in recent years, the characteristic length reynolds number is low due to the small size of the aircrafts, the low flying speed, or the low air density of the flying environment (re=10 4 ～10 6 ). Under the condition of low Reynolds number, the viscous effect and the unsteady effect of the air are dominant, the flow state is mainly laminar flow, the momentum is small, the capability of stress-resistant gradient is weak, and the flow is easy to separate from the wall surface to generate laminar flow separation. After laminar flow separation, the aircraft lift decreases, drag increases and stall occurs, adversely affecting aerodynamic characteristics. It is therefore desirable to control flow to inhibit laminar flow separation and improve aircraft aerodynamic properties.
There are many current laminar flow separation flow control techniques, which can be classified into passive and active, depending on whether energy is consumed, the former involving localized deformation, gurney flaps, etc., and the latter involving blowing/suction, synthetic jets, plasmas, etc.
In various active flow control technologies, air source pipelines are required to be arranged in a machine body in the control methods of blowing/sucking and the like, and the mechanism is complex; the plasma flow control technology requires a high-voltage power supply, and the control system is very difficult to miniaturize
Disclosure of Invention
In view of the above, the invention provides a laminar flow separation control method based on local vibration of the surface of a wing, which can simplify the structure of a control system, reduce the volume and obtain a good laminar flow separation control effect.
A laminar flow separation control method based on local vibration of wing surface is characterized in that a flexible structure and a driving mechanism for driving the flexible structure to vibrate are arranged on the local part of the wing surface, the flexible structure vibrates reciprocally around a balance position under the action of the driving mechanism or external airflow, and the displacement of one point of the wing surface in a vibration area is determined by the deformation quantity in the longitudinal direction of the wing chord and the distribution rule of the deformation quantity along the wing chord length direction.
Further, the expression of the deformation amount deltay in the direction perpendicular to the chord length direction of the airfoil is:
wherein: a is the amplitude of the maximum point of deformation;
controlling the distribution of deformation along the chord length direction of the airfoil profile for the normalized x coordinate; ω is angular frequency equal to 2pi times the vibration frequency, ω=2pi f; t is time.
Further, the distribution rule of the deformation along the chord length direction of the airfoil is as follows:
wherein x is 1 、x 2 And x represents the x coordinates of the left and right end points and the midpoint of the deformed region, respectively.
Further, the vibration modes and vibration positions of the flexible structure are defined differently.
Further, the driving mechanism adopts a pneumatic linear vibrator.
The beneficial effects are that:
1. according to the laminar flow separation control method based on the local vibration of the wing surface, only small-amplitude vibration of the local surface of the wing is required to be generated, so that the structure of a control system is greatly simplified, and the volume is reduced; and the controllers can be flexibly arranged according to the specific conditions of different wings and wing sections.
2. According to the laminar flow separation control method based on the local vibration of the wing surface, energy is injected into the fluid of the boundary layer through the vibration of the small-scale local structure of the wing surface, so that the capability of flow resistance to the reverse pressure gradient is enhanced, and the flow separation can be effectively inhibited.
Drawings
FIG. 1 is a schematic illustration of a local vibration deformation mode and coordinate system definition of an airfoil;
FIG. 2 is a graph of airfoil lift coefficient versus time;
FIG. 3 is a graph of airfoil drag coefficient versus time;
FIG. 4 is a contour-flow diagram of instantaneous pressure coefficients.
Detailed Description
The invention will now be described in detail by way of example with reference to the accompanying drawings.
The invention provides a laminar flow separation control method based on local vibration of the surface of an airfoil, wherein a flexible structure and a driving mechanism for driving the flexible structure to vibrate are arranged on the local part of the surface of the airfoil, the flexible structure vibrates reciprocally around a balance position under the action of the driving mechanism or external airflow, and the vibration mode is shown in figure 1. The displacement expression of one point of the wing-shaped surface in the vibration area is shown as the formula (1) and the formula (2)
In the formula (1), deltay is the deformation in the direction perpendicular to the chord length of the airfoil, and A is the amplitude of the maximum deformation point;
controlling the distribution of deformation along the chord length direction of the airfoil profile for the normalized x coordinate; ω is angular frequency equal to 2pi times the vibration frequency, ω=2pi f; t is time. Let the distribution rule of deformation along the wing section chord length direction be:
x in formula (2) 1 、x 2 And x represents the x coordinates of the left and right end points and the midpoint of the deformed region, respectively.
Figures 2 and 3 show flow control by using the laminar flow separation control method based on local vibration of the wing surface according to the invention, which is calculated by numerical simulation, under the flight condition of low Reynolds number (Reynolds number Re=3×10) 4 Angle of attack α=4°), the lift coefficient of the E387 airfoil, the drag coefficient curve, and the uncontrolled condition, wherein the parameters of the controller are taken as: deformation region positions 0 to 0.1c, excitation frequency f=f 0 Excitation amplitude a=2×10 -3 c (c is airfoil chord length, f 0 The vortex shedding frequency of the airfoil in the uncontrolled state). In fig. 2 and 3, the solid line indicates the uncontrolled condition, and the dotted line indicates the controlled condition; the curve represents the transient and the straight line represents the time average. Compared with the uncontrolled condition, the time average value of the unsteady lift coefficient of the airfoil after the flow control is added is increased by about 36%, the time average value of the resistance coefficient is reduced by about 33%, and the lift-drag ratio time average value is increased by about 102%, so that the laminar flow separation control method based on the local vibration of the surface of the airfoil has obvious lift-increasing and drag-reducing effects. FIG. 4 shows a comparison of instantaneous pressure coefficient contours-flow patterns of the flow around an airfoil under controlled conditions with those under uncontrolled conditions. It can be seen that after the addition of flow control, the separation zone behind the upper surface of the airfoil disappears and instead a series of vortices move downstream along the upper surface of the airfoil and the pressure at the vortices is lower and thus the lift force of the controlled situation is greater.
From the above results, it can be seen that: the laminar flow separation control method based on the local vibration of the wing surface can obtain an obvious laminar flow separation control effect under the condition that a control system is simple in structure and small in volume.
In summary, the above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (2)
1. A laminar flow separation control method based on local vibration of the surface of an airfoil is characterized in that a flexible structure and a driving mechanism for driving the flexible structure to vibrate are arranged on the local part of the surface of the airfoil, the driving mechanism adopts a pneumatic linear vibrator, the flexible structure makes reciprocating vibration around a balance position under the action of the driving mechanism or external airflow, and the displacement of one point of the surface of the airfoil in a vibration area is determined by deformation quantity perpendicular to the chord length direction of the airfoil and the distribution rule of the deformation quantity along the chord length direction of the airfoil;
the expression of the deformation delta y perpendicular to the chord length direction of the airfoil is as follows:
wherein: a is the amplitude of the maximum point of deformation;
controlling the distribution of deformation along the chord length direction of the airfoil profile for the normalized x coordinate; ω is angular frequency equal to 2pi times the vibration frequency, ω=2pi f; t is time;
the distribution rule of the deformation along the chord length direction of the airfoil is as follows:
wherein x is 1 、x 2 And x * The x coordinates of the left and right end points and the midpoint of the deformed region are represented, respectively.
2. The method for controlling laminar flow separation based on local vibration of a wing surface according to claim 1, wherein the vibration modes and vibration positions of the flexible structure are defined differently.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110113589.6A CN112810800B (en) | 2021-01-27 | 2021-01-27 | Laminar flow separation control method based on local vibration of wing surface |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110113589.6A CN112810800B (en) | 2021-01-27 | 2021-01-27 | Laminar flow separation control method based on local vibration of wing surface |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112810800A CN112810800A (en) | 2021-05-18 |
| CN112810800B true CN112810800B (en) | 2023-06-16 |
Family
ID=75859718
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110113589.6A Active CN112810800B (en) | 2021-01-27 | 2021-01-27 | Laminar flow separation control method based on local vibration of wing surface |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112810800B (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB605765A (en) * | 1946-01-04 | 1948-07-29 | Norman Kenneth Walker | Improvements in or relating to aerofoil sections for low reynolds numbers |
| US5209438A (en) * | 1988-06-20 | 1993-05-11 | Israel Wygnanski | Method and apparatus for delaying the separation of flow from a solid surface |
| IL121164A (en) * | 1997-06-26 | 2002-03-10 | Univ Ramot | Airfoil with dynamic stall control by oscillatory forcing |
-
2021
- 2021-01-27 CN CN202110113589.6A patent/CN112810800B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN112810800A (en) | 2021-05-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20230202646A1 (en) | Method and apparatus for mitigating trailing vortex wakes of lifting or thrust generating bodies | |
| Wood et al. | Control of vortical lift on delta wings by tangential leading-edge blowing | |
| US7686256B2 (en) | Conformal aero-adaptive nozzle/aftbody | |
| Greenblatt et al. | The control of flow separation by periodic excitation | |
| US7874525B2 (en) | Method and system for fully fixed vehicle control surfaces | |
| US8016245B2 (en) | Dynamic bumps for drag reduction at transonic-supersonic speeds | |
| CN108001669B (en) | Leading edge slat noise suppression method based on zero-mass jet control | |
| EP2841338A1 (en) | Method of using an active flow control system for lift enhancement or destruction | |
| US20160280358A1 (en) | Hybrid Flow Control Method for Simple Hinged Flap High-Lift System | |
| Rubbert et al. | A general three-dimensional potential-flow method applied to V/STOL aerodynamics | |
| Helin et al. | Effects of trailing-edge jet entrainment on delta wing vortices | |
| CN104176241A (en) | High-efficiency pneumatic layout structure of synergistic jet for high-altitude propeller and control method | |
| McManus et al. | Airfoil performance enhancement using pulsed jet separation control | |
| CN105173064B (en) | Tangential slit, which is blown, controls the method transonic speed buffeted and blowning installation | |
| CN112810800B (en) | Laminar flow separation control method based on local vibration of wing surface | |
| CN115520373A (en) | Jet flow control mechanism for controlling airflow direction of flow field at trailing edge of aircraft wing | |
| Ahluwalia et al. | CFD analysis on different shapes of winglet at low subsonic flow | |
| Rojewski et al. | NUMERCIAL ANALYSIS OF INFLUENCE OF THE WING IN GROUND EFFECT ON AIRCRAFT LIFT COEFFICIENT AND ON CAR DOWNFORCE COEFFICIENT | |
| CN113148148B (en) | Stability augmentation circulation control method of ground effect vehicle and stability augmentation type ground effect vehicle | |
| Kornilov et al. | Effect of air blowing and suction through single slots on the aerodynamic performances of an airfoil | |
| Fatahian et al. | The effect of suction jet angle on aerodynamic performance of NACA 0012 flapped airfoil–a CFD approach | |
| CN108163184A (en) | Air blowing circular rector self-regulation aircraft | |
| Didwania et al. | Analysis of stalling over FLAPED wing of an aeroplane by CFD code | |
| Nithya et al. | Design and performance analysis of bump surface in an airfoil | |
| EP3812227A1 (en) | Vehicle control |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |