CN103407574B - Novel efficient notch airfoil shape of parafoil unmanned plane and optimum design method thereof - Google Patents
Novel efficient notch airfoil shape of parafoil unmanned plane and optimum design method thereof Download PDFInfo
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- CN103407574B CN103407574B CN201310400562.0A CN201310400562A CN103407574B CN 103407574 B CN103407574 B CN 103407574B CN 201310400562 A CN201310400562 A CN 201310400562A CN 103407574 B CN103407574 B CN 103407574B
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Abstract
The invention provides a notch airfoil shape of a stamping parafoil and an optimum design method thereof. The optimum design method comprises the following steps of selecting a high aerodynamic efficiency base airfoil shape, designing a front edge notch and designing front edge notch parameter optimization. Compared with a conventional traditional CLARK-Y notch airfoil shape, the notch airfoil shape has the advantages that the max thickness of the notch airfoil shape is large, the thickness distribution is uniform, the space of a parafoil air chamber is large, and the notch airfoil shape is beneficial to improving of the charge efficiency and the charge rigidity of the parafoil; as the distribution of surface pressure along a thread direction is uniform, the notch airfoil shape is beneficial to arrangement of a parafoil parachute cord, and the pitching driving efficiency is improved; the stalling angle is large, the usable aerodynamic efficiency is high, and the notch airfoil shape has the large stalling angle range for smooth and stable control.
Description
Technical field
The present invention relates to a kind of parafoil unmanned plane ram air parachute wing section, be specifically related to a kind of parafoil unmanned plane notch airfoil.The present invention, except being applicable to parafoil unmanned plane, is also applicable to manufacturing and designing of other ram air parachute.
Background technology
Parafoil unmanned air vehicle technique utilizes ram air parachute to substitute traditional wing, for parafoil unmanned plane provides lift, and the novel unmanned plane of a class of formation.Ram air parachute is subject to aspect, the restriction of the factor of parachute-opening characteristic, aerodynamic parameter optimal design can not be carried out as traditional fixed wing, therefore, the optimal design of notch airfoil becomes the key improving parafoil unmanned plane aeroperformance, its performance and the performance of efficiency to ram air parachute have deciding factor, directly affect parachute-opening and the parafoil unmanned plane during flying performance of ram air parachute.
The research of High Performance aerofoil profile is a basic investigation of ram air parachute development.High lift, low resistance, stalling incidence are large, and maximum lift-drag ratio is high, good charging, and inflation rigidity is large etc. is the target that ram air parachute notch airfoil is pursued.Traditional notch airfoil is aerofoil profile based on CLARK-Y and Li Siman 7808 substantially, carries out the formation of leading edge opening, and the lift of these notch airfoil is large not, and stalling incidence is large not, and maximum ga(u)ge is large not.Therefore the notch airfoil that a kind of pneumatic efficiency is high, thickness is large is designed very necessary.
Because the flying speed of parafoil unmanned plane is very low, usually select Low Speed Airfoil, as CLARK-Y or NACA 4-digit number airfoil modification.The aerofoil profile of early stage parafoil is CLARK-Y, and a kind of aerofoil profile being called Li Siman appears in the eighties, and it has the in-use performance glide ratio being better than CLARK-Y approximately to increase by 0.2 ~ 0.4, but pneumatic efficiency is still good not.Improved type closes leading edge parafoil, is not continuing to use common CLARK-Y aerofoil profile, but adopts LS (1) wing section that can reduce induced drag.At present, China's ram air parachute notch airfoil mostly is the aerofoil profile of carrying out front edge slit design on CLARK-Y aerofoil profile basis.As ram air parachute wing section, there is following shortcoming in CLARK-Y notch airfoil:
(1) maximum camber position is forward, easily causes aerodynamic loading along tangential skewness, mainly concentrates on nearby edge place, makes umbrella rope discontinuity;
(2) lower aerofoil is straight, and the start position of front edge slit, on the most leading edge point of the string of a musical instrument, easily causes parafoil upper surface premature disengagement, as shown in Figure 1;
(3) CLARK-Y notch airfoil is in the stall of low incidence state, and stalling incidence is about 5 °, as shown in Figure 2, is unfavorable for the use of maximum lift-drag ratio, and pneumatic efficiency reduces, and also makes the pitch attitude of ram air parachute control to be restricted simultaneously.
Summary of the invention
Problem to be solved by this invention---overcome the deficiency of CLARK-Y notch airfoil, design new and effective notch airfoil, this aerofoil profile is low speed high lift aerofoil profile, has that stalling incidence is large, stalling characteristics good, be evenly distributed along tangential aerodynamic loading feature.
Technical solution of the present invention---select the basic aerofoil profile of high pneumatic efficiency, by leading edge by certain angle with highly design front edge slit, and carry out front edge slit Parameters Optimal Design.
Basis aerofoil profile is selected: select aerofoil profile based on applicable aerofoil profile to be very crucial, must take into account the constructional feature of aerodynamic performance and ram air parachute simultaneously.From the viewpoint of aerodynamic performance, require that aerofoil profile has higher 1ift-drag ratio, mild stalling characteristics, state has wider stable angle-of-attack range partially under manipulation trailing edge; Take into account ram air parachute structure, technological requirement simultaneously.Table 1 rises group characteristic (Re=300000 for part aerofoil profile during low-speed operations, α=6 °), data show GA (W)-1, E387 (A), E387 (C), E387 (E), Goe 417a, LRN1007 (B) have higher pneumatic efficiency.
Table 1 part aerofoil profile rise group characteristic (Re=300000)
Basic aerofoil profile in the present invention selects GA (W)-1 aerofoil profile, mainly contains the following aspects reason:
First, GA (W)-1 aerofoil profile is by the advanced high lift aerofoil profile of computational aerodynamics method design.From aerodynamic performance and geometric properties aspect, there is following features:
1. upper surface leading-edge radius is large, to reduce negative pressure peak under At High Angle of Attack, and therefore postpones airfoil stall;
2. aerofoil profile upper surface is more smooth, and load diatibution is even;
3. aerofoil profile is having larger camber near trailing edge place lower surface, and has the approximately equalised blunt trailing edge of upper and lower surface slope.
Secondly, from the angle as ram air parachute basis airfoil geometry structure, GA (W)-1 aerofoil profile has the following advantages:
1. in GA (W)-1 aerofoil profile, lower aerofoil is more smooth, and air-flow can pass through more gently, and load diatibution is even, umbrella rope uniform force;
2. profile thickness is comparatively large, has the relative thickness of 17%.Comparatively speaking, the relative thickness of traditional CLARK-Y parafoil aerofoil profile is 11.7%.Relative thickness is large, and plenum space is relatively large, can improve parafoil charge efficiency and inflation rigidity simultaneously;
3. leading-edge radius of airfoil is large, and the more difficult separation of air-flow, canopy more easily stitches accurately.
Notch airfoil notch parameters optimal design considers front edge slit angle and cut height two aspects.The two is inter-related, when otch start position is determined, then and cut angle and cut height one_to_one corresponding.
Front edge slit angle and cut height are determined: the position dimension design of front edge slit is generally half-way house, and otch keeps forming square impact press strip part with incoming flow as far as possible, both can ensure that ram air parachute was inflated, keep parafoil shape, and be unlikely to again to lose too many aeroperformance.By balance aeroperformance and inflation performance, determine that front edge slit angle (angle of aerofoil profile horizon and the otch extended line) θ of notch airfoil of the present invention is 39 °, the starting point of otch is the most leading edge point of aerofoil profile, the corresponding cut height ratio of chord length (the otch straight-line distance with) h is 5.2%, sees accompanying drawing 4.
Stagger angle is determined: in order to utilize the optimum aerodynamic characteristic of notch airfoil, and the scope of notch airfoil stagger angle is 6 ° ~ 8 °.
When the ram air parachute of parafoil unmanned plane launches, first parafoil realizes the inflation to ram air parachute by front edge slit, and air-flow enters parafoil inner plenum by front edge slit, and after inflation terminates, parafoil keeps " wing shapes ", enters cruising rating.
3, beneficial effect---proved by numerical value emulation method, compared with CLARK-Y notch airfoil, the permanent flat rigid model aerodynamic characteristic tool flown under state in notch airfoil low speed low latitude of the present invention has the following advantages:
(1) relative to conventional traditional C LARK-Y notch airfoil, the maximum ga(u)ge of notch airfoil of the present invention is large, and thickness distribution is even, and parafoil plenum space is large, is more conducive to improving the charge efficiency of parafoil and inflation rigidity, sees accompanying drawing 5;
(2) relative to conventional traditional C LARK-Y notch airfoil, notch airfoil surface pressure of the present invention along string of a musical instrument directional spreding evenly, be conducive to the layout of parafoil umbrella rope, improve pitch control efficiency;
(3) relative to conventional traditional C LARK-Y notch airfoil, notch airfoil stalling incidence of the present invention is large, and available pneumatic efficiency is high, has larger steady manipulation angle-of-attack range.
Accompanying drawing explanation
Fig. 1 is that the boundary-layer that in prior art, front edge slit causes is separated schematic diagram;
Fig. 2 is CLARK-Y wing section lift efficiency in prior art;
Fig. 3 is GA (W)-1 geometric shape in the present invention;
Fig. 4 is the front edge slit of notch airfoil of the present invention;
Fig. 5 is that the present invention and conventional wing section geometric shape contrast;
Fig. 6 is that in the present invention, notch airfoil installs and uses schematic diagram;
Fig. 7 is notch airfoil aerodynamic characteristic in the present invention;
Fig. 8 is that in the present invention, stagger angle is the flowing of 6 ° of inflation done states;
Fig. 9 the present invention and conventional cruise state wing section distribution of pressure contrast.
Description of reference numerals:
11: laminar sublayer; 12: turbulent boundary layer; 21:CLARK-Y notch airfoil; 22: notch airfoil of the present invention; 1: parafoil front edge slit; 2: umbrella rope; 3: trailing edge control wire; 4: canopy; 5: air chamber.
Detailed description of the invention
[embodiment 1]
As shown in Figure 6, notch airfoil of the present invention is connected with unmanned aerial vehicle body by umbrella rope 2, by the steering wheel on trailing edge control wire 3 and fuselage to connecting.During inflation, air-flow passes in and out parafoil air chamber 5 by front edge slit 1, makes canopy 4 in air foil shape and keeps inflation rigidity, and after inflation terminates, parafoil, horizontal by α angle, for pulling trailing edge control wire by steering wheel, realizes the control to α.
[embodiment 2]
Adopt CFD method to inflate the aerodynamic characteristic after terminating to notch airfoil of the present invention to analyze, during reynolds number Re=0.66e+06, lift efficiency and 1ift-drag ratio characteristic are shown in accompanying drawing 7, when °-8 °, stagger angle α=6, there is maximum lift-drag ratio, and the present invention is in °-12 °, stagger angle α=0, is stable pitch control scope.Flow characteristic wherein when stagger angle α=6 ° is shown in accompanying drawing 8, and notch airfoil distribution of pressure is shown in accompanying drawing 9.
Wherein reynolds number Re is the ratio of fluid inertia force and force of cohesion, ρ Vl/ μ, and wherein V is flow velocity, and l is the length flowing through object, and ρ is density, and μ is fluid viscosity coefficient.The characteristic of aerofoil profile is very large by the impact of Reynolds number during its motion, and laminar flow or turbulent flow during impact flowing, whether flow separation occurs.
Relative to conventional traditional C LARK-Y notch airfoil, the maximum ga(u)ge of notch airfoil of the present invention is large, and thickness distribution is even, and parafoil plenum space is large, is more conducive to improving the charge efficiency of parafoil and inflation rigidity; Surface pressure along string of a musical instrument directional spreding evenly, be conducive to the layout of parafoil umbrella rope, improve pitch control efficiency; Stalling incidence is large, and available pneumatic efficiency is high, has larger steady manipulation angle-of-attack range.
Those skilled in the art, can be improved according to the above description or be converted, and all these improve and convert the protection domain that all should belong to claims of the present invention.
Claims (5)
1. a ram air parachute notch airfoil, this aerofoil profile is low speed high lift aerofoil profile, it is characterized in that, the basic aerofoil profile of described notch airfoil selects GA (W)-1 aerofoil profile;
The front edge slit angle θ of described notch airfoil is 39 °, and corresponding cut height h is 5.2%;
The starting point of described otch is the most leading edge point of aerofoil profile;
The scope of described notch airfoil stagger angle α is 6 ° ~ 8 °.
2. notch airfoil according to claim 1, is characterized in that, wherein cut height represents the ratio of otch straight-line distance and chord length.
3. notch airfoil according to claim 1, is characterized in that, described aerofoil profile is used for parafoil unmanned plane.
4. a notch airfoil installation method, for installing notch airfoil as claimed in claim 3, it is characterized in that, described notch airfoil is connected with unmanned aerial vehicle body by umbrella rope, be connected with the steering wheel on fuselage by trailing edge control wire, during inflation, air-flow, by front edge slit turnover parafoil air chamber, makes canopy be air foil shape and keeps inflation rigidity, after inflation terminates, parafoil, horizontal by α angle, pulls trailing edge control wire by steering wheel, realizes the control to stagger angle α.
5. an Optimization Design for ram air parachute notch airfoil, is characterized in that, said method comprising the steps of:
1) the basic aerofoil profile of high pneumatic efficiency is selected: basic aerofoil profile selects GA (W)-1 aerofoil profile;
2) front edge slit is designed: front edge slit keeps forming square impact press strip part with incoming flow as far as possible, both can ensure that ram air parachute is inflated, keep parafoil shape, be unlikely to again to lose too many aeroperformance,
3) front edge slit Parameters Optimal Design: by balance aeroperformance and inflation performance, determine that the front edge slit angle θ of notch airfoil of the present invention is 39 °, the starting point of otch is the most leading edge point of aerofoil profile, and corresponding cut height h is 5.2%.
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| CN201310400562.0A CN103407574B (en) | 2013-09-05 | 2013-09-05 | Novel efficient notch airfoil shape of parafoil unmanned plane and optimum design method thereof |
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| CN103407574B true CN103407574B (en) | 2015-07-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109292110A (en) * | 2018-08-23 | 2019-02-01 | 淮阴工学院 | A kind of parafoil longitudinal direction Aerodynamic Coefficient estimating system and its evaluation method |
| CN113044199B (en) * | 2021-04-20 | 2023-12-15 | 西北工业大学 | High-performance low-Reynolds number serial laminar flow wing profile based on coupling wing layout unmanned aerial vehicle |
| CN114987755B (en) * | 2022-05-18 | 2023-04-25 | 南京航空航天大学 | Automatic wing profile modification method for parafoil |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0442513A1 (en) * | 1990-02-14 | 1991-08-21 | Kenbec Ltd. | Paraglider |
| CN202911949U (en) * | 2012-10-31 | 2013-05-01 | 航宇救生装备有限公司 | Parafoil |
| CN203094446U (en) * | 2013-01-10 | 2013-07-31 | 襄阳宏伟航空器有限责任公司 | Parawing system for wheel type parawing |
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2013
- 2013-09-05 CN CN201310400562.0A patent/CN103407574B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0442513A1 (en) * | 1990-02-14 | 1991-08-21 | Kenbec Ltd. | Paraglider |
| CN202911949U (en) * | 2012-10-31 | 2013-05-01 | 航宇救生装备有限公司 | Parafoil |
| CN203094446U (en) * | 2013-01-10 | 2013-07-31 | 襄阳宏伟航空器有限责任公司 | Parawing system for wheel type parawing |
Non-Patent Citations (1)
| Title |
|---|
| 翼伞弧面下反角、翼型和前缘切口对翼伞气动性能的影响;朱旭等;《航空学报》;20120229;第33卷(第7期);1189-1200 * |
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