CN103407574A - 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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- CN103407574A CN103407574A CN2013104005620A CN201310400562A CN103407574A CN 103407574 A CN103407574 A CN 103407574A CN 2013104005620 A CN2013104005620 A CN 2013104005620A CN 201310400562 A CN201310400562 A CN 201310400562A CN 103407574 A CN103407574 A CN 103407574A
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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 and use the ram air parachute wing section, be specifically related to a kind of parafoil unmanned plane otch aerofoil profile.The present invention, except being applicable to the parafoil unmanned plane, also is applicable to manufacturing and designing of other ram air parachute.
Background technology
Parafoil unmanned plane technology is to utilize ram air parachute to substitute traditional wing, for the 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, can not as traditional fixed wing, carry out the aerodynamic parameter optimal design, therefore, the optimal design of otch aerofoil profile becomes the key that improves parafoil unmanned plane aeroperformance, its performance and efficiency have deciding factor to the performance of ram air parachute, 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 the large grade of inflation rigidity is the target that ram air parachute otch aerofoil profile is pursued.Traditional otch aerofoil profile is to be basic aerofoil profile at CLARK-Y and Li Siman 7808 substantially, carries out the formation of leading edge opening, and the lift of these otch aerofoil profiles is large not, and stalling incidence is large not, and maximum ga(u)ge is large not.Therefore design the otch aerofoil profile that a kind of pneumatic efficiency is high, thickness is large 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, the eighties occurs a kind of aerofoil profile that is called Li Siman, and it has the in-use performance glide ratio that is better than CLARK-Y approximately to increase by 0.2～0.4, but pneumatic efficiency is still good not.Improved type sealing leading edge parafoil, do not continuing to use common CLARK-Y aerofoil profile, but adopting LS (1) wing section that can reduce induced drag.At present, China's ram air parachute otch aerofoil profile mostly is the aerofoil profile of carrying out the leading edge incision design on CLARK-Y aerofoil profile basis.As the ram air parachute wing section, there is following shortcoming in CLARK-Y otch aerofoil profile:
(1) the 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 leading edge otch, on the 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 otch aerofoil profile 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 the pitch attitude control of ram air parachute is restricted.
Summary of the invention
Problem to be solved by this invention---overcome the deficiency of CLARK-Y otch aerofoil profile, design new and effective otch aerofoil profile, this aerofoil profile is low speed high lift aerofoil profile, has that stalling incidence is large, stalling characteristics good, along the tangential aerodynamic loading characteristics that are evenly distributed.
Technical solution of the present invention---select the basic aerofoil profile of high pneumatic efficiency, leading edge is pressed to certain angle and height design leading edge otch, and carry out leading edge notch parameters optimal design.
The basis aerofoil profile is selected: the aerofoil profile of selecting to be applicable to is very crucial as basic aerofoil profile, must take into account simultaneously the constructional feature of aerodynamic performance and ram air parachute.From the aerodynamic performance aspect, consider, require aerofoil profile to have higher 1ift-drag ratio, mild stalling characteristics, wider stable angle-of-attack range arranged handling under trailing edge state partially; Take into account simultaneously ram air parachute structure, technological requirement.Table 1 when the low-speed operations part aerofoil profile rise group characteristic (Re=300000, α=6 °), data show that 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 is selected GA (W)-1 aerofoil profile, mainly contains the following aspects reason:
At first, GA (W)-1 aerofoil profile is the advanced high lift aerofoil profile by the design of computational aerodynamics method.From aerodynamic performance and geometric properties aspect, have following features:
1. the upper surface leading-edge radius is large, to reduce negative pressure peak value under At High Angle of Attack, and therefore postpones airfoil stall;
2. the aerofoil profile upper surface is more smooth, and load is evenly distributed;
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. on GA (W)-1 aerofoil profile, lower aerofoil is more smooth, and air-flow can pass through more gently, and load is evenly distributed, and the umbrella rope is stressed evenly;
2. profile thickness is larger, has 17% relative thickness.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. the aerofoil profile leading-edge radius is large, the more difficult separation of air-flow, and canopy more easily stitches accurately.
Otch aerofoil profile notch parameters optimal design is considered leading edge cut angle and two aspects of cut height.The two is inter-related, and in the situation that the otch start position is determined, cut angle and cut height are corresponding one by one.
Leading edge cut angle and cut height are determined: the position dimension design of leading edge otch is generally half-way house, and otch keeps forming square impact press strip spare with incoming flow as far as possible, both can guarantee the ram air parachute inflation, keep the parafoil shape, be unlikely to again to lose too many aeroperformance.By balance aeroperformance and inflation performance, leading edge cut angle (angle of aerofoil profile horizon and the otch extended line) θ that determines otch aerofoil profile of the present invention is 39 °, the starting point of otch is the 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 otch aerofoil profile, the scope of otch aerofoil profile stagger angle is 6 °～8 °.
When the ram air parachute of parafoil unmanned plane launched, at first parafoil realized the inflation to ram air parachute by the leading edge otch, and air-flow enters the parafoil inner plenum by the leading edge otch, and after inflation finished, parafoil kept " wing shapes ", enters cruising rating.
3, beneficial effect---by numerical value emulation method, prove, compare with CLARK-Y otch aerofoil profile, the permanent flat rigid model aerodynamic characteristic flown under state in otch aerofoil profile low speed of the present invention low latitude has following advantage:
(1) with respect to conventional traditional C LARK-Y otch aerofoil profile, the maximum ga(u)ge of otch aerofoil profile of the present invention is large, and thickness distribution is even, and parafoil air chamber space is large, more is conducive to improve the charge efficiency and inflation rigidity of parafoil, sees accompanying drawing 5;
(2) with respect to conventional traditional C LARK-Y otch aerofoil profile, otch airfoil surface pressure of the present invention is more evenly distributed along string of a musical instrument direction, is conducive to the layout of parafoil umbrella rope, improves pitch control efficiency;
(3) with respect to conventional traditional C LARK-Y otch aerofoil profile, the otch airfoil stall angle of attack of the present invention is large, and available pneumatic efficiency is high, has larger steady manipulation angle-of-attack range.
The accompanying drawing explanation
Fig. 1 is that the boundary-layer that in prior art, the leading edge otch causes separates 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 leading edge otch of otch aerofoil profile of the present invention;
Fig. 5 is the present invention and the contrast of wing section commonly used geometric shape;
Fig. 6 is that in the present invention, the otch aerofoil profile is installed and used schematic diagram;
Fig. 7 is otch aerofoil profile aerodynamic characteristic in the present invention;
Fig. 8 is that in the present invention, stagger angle is that 6 ° of inflation done states flow;
Fig. 9 the present invention and the contrast of traditional cruising condition wing section distribution of pressure.
Description of reference numerals:
11: laminar sublayer; 12: turbulent boundary layer; 21:CLARK-Y otch aerofoil profile; 22: otch aerofoil profile of the present invention; 1: parafoil leading edge otch; 2: the umbrella rope; 3: the trailing edge control wire; 4: canopy; 5: air chamber.
The specific embodiment
[embodiment 1]
As shown in Figure 6, otch aerofoil profile 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, by leading edge otch 1 turnover parafoil air chamber 5, makes canopy 4 be air foil shape and keeps inflation rigidity, and after inflation finished, parafoil, horizontal by the α angle, for by steering wheel, pulling the trailing edge control wire, was realized the control to α.
[embodiment 2]
Adopt the aerodynamic characteristic after the CFD method finishes otch aerofoil profile inflation 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 stagger angle α=6 °-8 °, has maximum lift-drag ratio, and the present invention is stable pitch control scope in stagger angle α=0 °-12 °.Wherein the flow characteristic when stagger angle α=6 ° is shown in accompanying drawing 8, and otch aerofoil profile 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 that flows through object, and ρ is density, and μ is the fluid viscosity coefficient.The impact of the Reynolds number the when characteristic of aerofoil profile is subjected to its motion is very large, laminar flow or turbulent flow when impact is flowed, and whether flow separation occurs.
With respect to conventional traditional C LARK-Y otch aerofoil profile, the maximum ga(u)ge of otch aerofoil profile of the present invention is large, and thickness distribution is even, and parafoil air chamber space is large, more is conducive to improve the charge efficiency and inflation rigidity of parafoil; Surface pressure is more evenly distributed along string of a musical instrument direction, is conducive to the layout of parafoil umbrella rope, improves 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 or conversion according to the above description, and all these improve and conversion all should belong to the protection domain of claims of the present invention.
Claims (8)
1. ram air parachute otch aerofoil profile, this aerofoil profile is low speed high lift aerofoil profile, it is characterized in that, the basic aerofoil profile of described otch aerofoil profile is to select GA (W)-1 aerofoil profile.
2. otch aerofoil profile according to claim 1, is characterized in that, the leading edge cut angle θ of described otch aerofoil profile is 39 °, and corresponding cut height h is 5.2%.
3. otch aerofoil profile according to claim 2, is characterized in that, wherein the starting point of otch is the leading edge point of aerofoil profile.
4. otch aerofoil profile according to claim 2, is characterized in that, wherein cut height means the ratio of otch straight-line distance and chord length.
5. otch aerofoil profile according to claim 1, is characterized in that, the scope of described otch aerofoil profile stagger angle α is 6 ° ~ 8 °.
6. otch aerofoil profile according to claim 1, is characterized in that, described aerofoil profile is for the parafoil unmanned plane.
7. according to a kind of otch aerofoil profile installation method of claim 6, it is characterized in that, described otch aerofoil profile is connected with unmanned aerial vehicle body by the umbrella rope, by the steering wheel on trailing edge control wire and fuselage to connecting; During inflation, air-flow, by leading edge otch turnover parafoil air chamber, makes canopy be air foil shape and keeps inflation rigidity, and after inflation finished, parafoil, horizontal by the α angle, pulled the trailing edge control wire by steering wheel, realized the control to stagger angle α.
8. the Optimization Design of a ram air parachute use otch aerofoil profile, is characterized in that, said method comprising the steps of:
1) select the basic aerofoil profile of high pneumatic efficiency: basic aerofoil profile is to select GA (W)-1 aerofoil profile; 2) design leading edge otch: the leading edge otch keeps forming square impact press strip spare with incoming flow as far as possible, both can guarantee the ram air parachute inflation, keeps the parafoil shape, is unlikely to again to lose too many aeroperformance; 3) leading edge notch parameters optimal design: by balance aeroperformance and inflation performance, determine that the leading edge cut angle θ of otch aerofoil profile of the present invention is 39 °, the starting point of otch is the 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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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN113044199A (en) * | 2021-04-20 | 2021-06-29 | 西北工业大学 | High-performance low Reynolds number tandem laminar flow wing section based on connecting wing layout unmanned aerial vehicle |
| CN114987755A (en) * | 2022-05-18 | 2022-09-02 | 南京航空航天大学 | Automatic wing-shaped reforming method of parafoil |
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| 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
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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)
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN113044199A (en) * | 2021-04-20 | 2021-06-29 | 西北工业大学 | High-performance low Reynolds number tandem laminar flow wing section based on connecting wing layout unmanned aerial vehicle |
| 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 |
| CN114987755A (en) * | 2022-05-18 | 2022-09-02 | 南京航空航天大学 | Automatic wing-shaped reforming method of parafoil |
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