CN1702019A - Bionic flapping method for minisize aircraft - Google Patents
Bionic flapping method for minisize aircraft Download PDFInfo
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- CN1702019A CN1702019A CN 200510082927 CN200510082927A CN1702019A CN 1702019 A CN1702019 A CN 1702019A CN 200510082927 CN200510082927 CN 200510082927 CN 200510082927 A CN200510082927 A CN 200510082927A CN 1702019 A CN1702019 A CN 1702019A
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Abstract
The invention relates to a bionic flapping method of mini airplane. Flapping upward stage comprises the following three sections: in preliminary stage flapping wings inverting downward and meanwhile flapping to speed-up to flapping angle of attack upward and flapping speed upward; in intermediate stage flapping wings keeping angle of attack upward and flapping speed upward constant; in ending stage flapping wings starting to turn over upward from angle of attack upward and meanwhile flap to slow down. Flapping downward stage also comprises the following three sections: in preliminary stage flapping wings inverting upward and meanwhile flapping to speed-up to flapping angle of attack downward and flapping speed downward; in intermediate stage flapping wings keeping angle of attack downward and flapping speed downward constant; in ending stage flapping wings starting to turn over downward from angle of attack downward and meanwhile flap to slow down. Flapping upward stage and flapping downward stage cross alternatively and processes cyclical movement. Compared with flapping mode of fruit fly, the present invention reduces friction factor of flapping wings greatly, enhances lift-drag ratio, alleviates feature difference of elevating force among different motor patterns of flapping mode and enhances stability.
Description
Technical field
The present invention relates to a kind of bionic flapping method that is used for minute vehicle.
Background technology
Minute vehicle, being called for short MAVs (Micro Air Vehicles or Micro Aerial Vehicles) is at first to be proposed by U.S. DARPA (Defense Advanced Research ProjectsAgency) in recent ten years and fast-developing new and high technology.Target is the minute vehicle that is similar to hummingbird or insect size in order to develop.MAVs has a extensive future.Military as scouting, target acquisition, weapon input, trunking traffic etc.Military theory man is arranged even think that MAV may change the pattern of future war.Civilian as photography, monitoring, investigation, patrol is sampled etc.
So far, many countries have all set up particular study mechanism, and drop into special reasearch funds, develop and develop the minute vehicle of various unique properties.Only the U.S. be engaged in the colleges and universities of the research and research unit just have 150 surplus family, develop very fastly, in a short period of time, just develop the experimental prototype of a collection of function admirable.Flying method roughly is divided into: fixed-wing, rotor and flapping wing three classes, wherein according to representational be " Microstar ", the Lincoln of Massachusetts Institute of Technology (MIT) breadboard " scouting bird ", " Mesicopter " of Stanford University, California faculty of engineering's " Microbat " and " the micromechanics insect " of University of California Berkeley etc. of Aerovironment company " black widow ", Sander company.The research of domestic minute vehicle has become hot issue, about tens units are carrying out the research of this respect, successively develop multiple model, and carried out preliminary flight test, but also have gap greatly apart from complete autonomous flight and the target that satisfies the practicability requirement.
A low speed MAVs is its principal character with low flight Reynolds number with making full use of the MEMs technology.Here the low Re scope at MAVs place does not have a definite scope, and in general Re is less than 105, and further micro-miniaturisation may drop to about 102.Minute vehicle is simply dwindling of orthodox flight device anything but, its aerodynamic force, structure design, engine installation, flight mechanics and Navigation Control all have the characteristics that are different from the orthodox flight device, they are not studied targetedly and solve, it is very difficult to reach the practicability target.The deficiency of the relevant pneumatics of low reynolds number is the maximum bottleneck of restriction minute vehicle development at present.
For the MAVs of principal dimensions more than 25cm, some increase steady measure before adopting on the fixed-wing basis, might solve the problem that obtains enough lift and stability.But for the minute vehicle of yardstick less than 15cm, may have only the bionical mechanics of employing, the way of the wing of fluttering could obtain enough 1ift-drag ratios.Along with the further micro-miniaturisation of aircraft size, the birds wing mode of fluttering up and down also will lose efficacy, thereby must imitate the mode of flapping of insect type.
At present both at home and abroad considering to be applied to clap the flapping during wing mode of motion of rotor aircraft, what expect all is directly to learn to hummingbird or insect, clap the wing by direct mimic biology and move and obtain enough lift, the most representative with the micromechanics fly that the University of California is developing.The mode of flapping that fruit bat is taked extensively exists in insect circle, and its unique reasonable grounds is arranged naturally, sees from the viewpoint of Pneu can obtain higher lift balance body weight and realize maneuvering flight.Understand fully that thoroughly its groundwork also must be from biology, physiology, multi-angles such as anatomy and biological evolution are researched and analysed.But when flapping the design of wing minute vehicle, directly imitate this mode of flapping simply, then can run into following difficulty:
(1) flap the wing drag coefficient much larger than lift coefficient, the average 1ift-drag ratio of the wing of flapping is lower, and the mechanical energy consumption that is used to overcome resistance accordingly is higher, causes quite a few energy consumption of the wing of flapping to be used for overcoming the resistance acting, and economy is relatively poor;
(2) flap between the wing different motion mode (leading, symmetry and lag behind) to rise drag characteristic difference huge, be not easy to control.
(3) mode of motion implements comparatively complexity, and the machine design difficulty carry out the wide-angle upset in the process of flapping and be difficult for realizing, and mechanism's complexity may cause in-house energy consumption to increase;
The purpose that scientists is studied bionics is to understand the biological mechanism that obtains " exceptional function ", and it is promoted the well-being of mankind.This research and application are anything but to the biological body structure, and copying word by word fully and simple imitation of behavior there is no need because do like that, usually can't realize, and often be difficult to produce a desired effect.Imitate birds flies as the mankind and design fixed wing aircraft, but then there is essential difference in engine installation with the propulsion modes of birds; Imitation muscular work mode is developed artificial muscle, but the principle of shrinking and extending has nothing in common with each other.
To insect flap the final purpose of wing flying method research and generally bionics Study there is no different, be in order to be disclosed in the Hydrodynamics Mechanism that the wing flying method of flapping under the low reynolds number condition obtains high lift, and with the design and the manufacturing of these thought guidance minute vehicles (MAVs).So research is different from traditional insect complexity mode of flapping, motion and structure realization are comparatively simple, but can rationally use the non-permanent high aerodynamic lift mechanism of the wing of flapping, and 1ift-drag ratio is higher, and the less mode of newly flapping of energy consumption is a very significant job.
Summary of the invention
Technology of the present invention is dealt with problems: overcome the deficiencies in the prior art, provide a kind of wing drag coefficient of flapping to reduce greatly, 1ift-drag ratio increases, obtaining the bionic flapping method that is used for minute vehicle that mechanical energy consumption reduces under the cooresponding lift benefit condition, this method has greatly relaxed fruit bat flaps and rises drag characteristic difference between the mode different motion mode (leading, symmetry and lag behind), has improved stability.
Technical solution of the present invention: be used for the bionic flapping method of minute vehicle, its characteristics are to comprise the following steps:
This flapping method claims to be flap (flapping) around the motion of wing root S. A. for back and forth to flap around the periodicity of wing root S. A.; The motion of the span to S. A. is rotation (rotation) around flapping; Flap the wing to the flapping of front lower place, be called and clap (downstroke) down; Flap the wing to the flapping of back upper place, be called arsis (upstoke); Arsis finishes to clap the incipient stage down, and the wing of flapping upwards rotates to be called and turns over (supination); Following bat finishes the arsis incipient stage, and the wing of flapping turns over (pronation) under rotating and being called, and the cycle of whenever flapping is divided into arsis and claps two stages down.
At first describe the arsis stage, the arsis stage is divided into three parts:
(1) wing of flapping turns under rotating the arsis incipient stage, and flapping simultaneously accelerates to the arsis angle of attack and arsis speed;
(2) wing of flapping keeps the arsis angle of attack and arsis speed constant substantially the arsis intermediary;
(3) the arsis ending phase wing of flapping begins to rotate from the arsis angle of attack in arsis intermediary and turns over the deceleration of flapping simultaneously;
The following bat stage also will be divided into three parts:
(1) clap down the incipient stage wing of flapping and rotate and turn over, flapping simultaneously accelerates to down the angle of attack and the following bat speed of clapping;
(2) clap down the intermediary and flap that to keep clapping down the angle of attack and following bat speed constant substantially for the wing;
(3) clap down the ending phase wing of flapping and under the following bat angle of attack of clapping the intermediary down begins to rotate, turn over the deceleration of flapping simultaneously;
One time arsis constitutes one-period with clapping down, and arsis and following bat stage hocket, and the oscillation cycle motion realizes flapping method of the present invention.
Principle of the present invention: find: (1) insect angle of attack such as wing constant speed leading edge delay stall effect in the process of flapping of flapping in the whirlpool by research summary that insect wing is flapped, make the wing not stall and keep high aerodynamic lift platform under big angle of attack condition of flapping, it is the flap deciding factor of the high aerodynamic lift most critical of the wing of insect, maximum lift contributions is provided, sees Fig. 2; (2) though one of factor that fast retarding efffect of the ending phase of flapping and fast acceleration effect of incipient stage also are high non-permanent aerodynamic lifts to be produced must cooperate suitable angle of attack variation, see that the leading mode lift coefficient of Fig. 2 changes.If angle of attack variation is improper, then the negative lift peak value can appear, and influence intermediary of flapping postpone the performance of stall effect effect, see Fig. 4 mode lift coefficient curve that lags behind; (3) the flap quick pull-up effect of the wing angle of attack of flapping in the process of constant speed is the another key factor (seeing Fig. 2 and Fig. 3) that obtains high non-permanent aerodynamic lift, and angle of attack variation is provided simultaneously.Find this high-drag peak value and the lower 1ift-drag ratio in addition that flip-flop movement brings simultaneously of going up but analyze.
The flapping method that proposes in view of above situation the present invention is keeping postponing favorable factors such as stall effect and fast acceleration and deceleration effect, when obtaining cooresponding non-permanent aerodynamic lift, the mode of bowing fast with the two ends of flapping up and down replaces quick pull-up, eliminated the constant speed unfavorable factor that the angle of attack fast pull-up effect brought of flapping, greatly reduce non-permanent resistance, thereby improved 1ift-drag ratio greatly, reduced mechanical energy consumption, relaxed the flap difference of aerodynamic characteristic between mode of fruit bat difference; The flapping method of uniqueness of the present invention makes that also applying the camber effect on flat board is flapped the wing becomes highly significant thing in addition.
The present invention's advantage compared with prior art is as follows:
(1) the present invention is when guaranteeing to obtain high aerodynamic lift, by reduce the front and rear edge checker fast with the angle of attack at the cycle two ends of partly flapping, the rotating manner that last lower aerofoil remains unchanged, replace the fast pull-up of traditional fruit bat wing angle of attack, leading edge is constant, the rotating manner of last lower aerofoil checker.Though traditional fruit bat wing constant speed fast pull-up lift mechanism of the angle of attack of flapping of flapping in the mode is disappeared, but greatly reduce the non-permanent aerodynamic drag of the wing of flapping, the very effective 1ift-drag ratio that has improved the wing of flapping: leading pattern improves 35.%, symmetric pattern improves 66.1%, hysteresis mode improves 150.% (seeing Table 1), thereby when obtaining cooresponding average lift coefficient, reduce and be used to overcome the mechanical energy consumption of resistance of flapping, improve mechanical efficiency greatly.
(2) greatly improve the flap aerodynamic characteristic of mode hysteresis mode of traditional fruit bat wing, relaxed the flap greatest differences of aerodynamic characteristic between three kinds of mode of motioies of mode of traditional fruit bat wing.
(3) for the minute vehicle of small scale, the thin flat plate wing is more practical, this shape and structure from insect wing can be confirmed, and this front and rear edge of the present invention alternately exactly is well suited for being applied to the thin plate wing, and on this mode basis of newly flapping of research, on thin flat plate is flapped the wing, apply camber and can effectively improve lift coefficient and 1ift-drag ratio, and for traditional fruit bat mode of flapping, it is postiche doing like this.
(4) angle that realizes from mechanism is considered, the present invention is also easier to realize that under the angle of attack condition of flapping less than 45 °, angle of attack variation of the present invention is littler than fruit bat angle of attack variation in the minute vehicle design.And 30 °-40 ° higher wing angle of attack scopes of flapping that are efficient.
Description of drawings
Fig. 1 is the wing motion scheme drawing of flapping of the present invention;
Fig. 2 is the fruit bat leading mode lift coefficient of the mode curve of flapping;
Fig. 3 is the fruit bat mode symmetry mode lift coefficient curve of flapping;
Fig. 4 is the fruit bat mode mode lift coefficient curve that lags behind of flapping;
Fig. 5 rotates for the mode of flapping of the present invention and the cireular frequency of flapping distributes;
Fig. 6 is the mode symmetry mode of the flapping of the present invention scheme drawing of flapping;
Rotate and the cireular frequency of flapping distributes by mode for fruit bat is flapped for Fig. 7;
Fig. 8 is the fruit bat mode symmetry mode scheme drawing of flapping of flapping;
Fig. 9 changes for the mode different modalities lift coefficient of flapping of the present invention;
Figure 10 changes for the mode different modalities drag coefficient of flapping of the present invention;
Figure 11 changes for the fruit bat mode different modalities lift coefficient of flapping;
Figure 12 changes for the fruit bat mode different modalities drag coefficient of flapping;
The mode of newly flapping under Figure 13 symmetric pattern and fruit bat are flapped mode apart from vorticity lines such as the long cross sections of wing root 60% exhibition.
The specific embodiment
The stage branch of flapping in monocycle of the present invention: arsis, clap down, on turn over, turn over down; According to the phase relation of flapping motion and rotating, the mode of flapping is divided in advance, the symmetrical and three kinds of mode of flapping that lag behind.The wing of flapping is called down to flapping of front lower place to be clapped, and the wing of flapping is called arsis to flapping of back upper place, and the wing of flapping turns under rotating and being called, and the wing of flapping upwards rotates to be called and turns over; Be called symmetric pattern when rotational motion with when flapping the acceleration and deceleration motion phase synchronization, when the rotational motion phase place is called leading pattern in advance when flapping acceleration and deceleration motion, otherwise be called hysteresis mode.Lead and lag mode phase difference can be selected arbitrarily.
Below in conjunction with Fig. 5 and Fig. 6 the present invention's mode of flapping is described in detail.Abscissa is the time in the monocycle among Fig. 5, and getting the dimensionless cycle in this example is 8.4, and ordinate is cireular frequency and the rotational angular velocity of flapping.Fig. 6 is the scheme drawing of flapping.
The present invention is divided into arsis stage and following bat stage at cycle of singly flapping, and the arsis stage is divided into three parts:
(1) wing of flapping turns under rotating the arsis incipient stage, and flapping simultaneously accelerates to the arsis angle of attack and arsis speed;
(2) wing of flapping keeps the arsis angle of attack and arsis speed constant substantially the arsis intermediary;
(3) the arsis ending phase wing of flapping begins to rotate from the arsis angle of attack in arsis intermediary and turns over the deceleration of flapping simultaneously;
The following bat stage also will be divided into three parts:
(1) clap down the incipient stage wing of flapping and rotate and turn over, flapping simultaneously accelerates to down the angle of attack and the following bat speed of clapping;
(2) clap down the intermediary and flap that to keep clapping down the angle of attack and following bat speed constant substantially for the wing;
(3) clap down the ending phase wing of flapping and under the following bat angle of attack of clapping the intermediary down begins to rotate, turn over the deceleration of flapping simultaneously;
One time arsis becomes one-period with clapping down, and arsis and following bat stage hocket, and the oscillation cycle motion realizes flapping method of the present invention.
The wing of flapping among the present invention can be the dull and stereotyped wing, also can be the wing of band camber; The wing of flapping can be rigid wings, also can be flex-wing.
The arsis angle of attack also can be different with the bat angle of attack can be identical at different cycles down; Flap the wing with respect to the arsis angle of attack of the working direction of flapping and clap the angle of attack down less than 90 °.
The flapping acceleration of arsis in the stage is the process from the arsis speed in 0 to arsis intermediary; The arsis speed of slowing down from the arsis intermediary of flapping in described arsis stage reduces to 0 process; The acceleration of flapping in described following bat stage is from 0 process to the following bat speed of clapping the intermediary down; The described deceleration of flapping of clapping ending phase down is the process from the following bat speed to 0 of clapping the intermediary down.
The upper and lower incipient stage of flapping flap quicken institute's time-consuming and ending phase deceleration institute time-consuming all greater than 0 smaller or equal to four/one-period; The two ends of flapping up and down, the wing of flapping rotate required time greater than 0 less than half of the cycle of flapping.
Flap up and down incipient stage and ending phase are flapped and are quickened and the characteristics of motion that meets of slowing down can be to satisfy to quicken the finish time and the cireular frequency time derivative of flapping the zero hour of slowing down is 0 arbitrary function, as trigonometric function or algebraic function etc.
The rule that the wing of flapping upset is met can be that satisfied upset beginning and rotational angular velocity time finish time inverse are 0 arbitrary function, as trigonometric function or algebraic function etc.
The mode of flapping of the present invention is flapped different as follows with the existing fruit bat wing:
Fig. 7 and Fig. 8 flap for the existing fruit bat wing and flap and the rotational angular velocity Changing Pattern and the scheme drawing of flapping in the monocycle.
The existing fruit bat wing characteristics of flapping are: clap the wing front and rear edge of flapping in the alternating movement up and down and remain unchanged, the wing of flapping facings the wind and the lee face alternate, the two ends angle of attack variation mode of flapping up and down is quick pull-up, sees that bullet is represented the nose of wing of flapping among Fig. 8, and the other end is a trailing edge.
Method of the present invention and the existing fruit bat wing mode of flapping is compared difference and is: (1) flap up and down beginning and finish two ends, the wing of flapping rotatablely move and obtain the angle of attack of flapping of next stage by the mode of bowing fast; (2) clapping the wing front and rear edge of flapping in the alternating movement up and down alternately changes; (3) flap that the wing facings the wind and lee face remains unchanged.The process of flapping other parts are identical.The aerofoil profile two ends all mark with bullet among Fig. 6, and the expression two ends all may become leading edge, the front and rear edge alternate.
Below by numerical simulation experiment the present invention is verified instantiation.
Be illustrated in figure 1 as the wing motion scheme drawing of flapping and provided three cover coordinates, XYZ is the inertial system that is fixed on the minute vehicle body; Xyz be fixed on the wing of flapping with system; X ' y ' z ' is that y ' axle overlaps with Y-axis, and with the moving coordinate system that the wing of flapping is flapped around Y-axis, wherein Y-axis and y ' axle overlap, and z axle and z ' axle overlap.The wing of flapping rotates around Y-axis and is called " flapping " or " brandishing ", and the angle of flapping is designated as φ, is called " rotation " around the upset of z axle, and pivot angle is designated as α, claims the angle of attack again, around Y-axis radius of gyration r
0The linear velocity at place is called the speed of flapping and is designated as u
t, cireular frequency φ flaps
t=u
t/ γ
0
Getting hovers, and the face that flies to flap is a horizontal surface, the intermediary angle of attack of flapping and the speed u that flaps
tConstant; The fast acceleration of beginning and ending phase slowed down accompanying rotation with fast.Quicken and slow down can adopt any-mode, the embodiment of the invention adopts following acceleration-deceleration mode, the intermediary of the flapping speed of flapping is got constant U
t, the formula of flapping is described below:
The beginning acceleration phase:
Finish the decelerating phase:
Wherein:
u
tBe the linear velocity of flapping, U is that reference velocity is got the monocycle speed u that on average flaps
i τ=tU/c, τ
1Quicken the time opening, τ
1+ Δ τ
1/ 2 quicken concluding time, τ
2Slow down the time opening τ
2+ Δ τ
1/ 2 slow down the concluding time, and the velocity variations of flapping rule is by τ
1, τ
2, Δ τ
t, U and τ
cDecision, τ
1Quicken the time opening, τ
2Time opening and Δ τ slow down
1Time span can be selected arbitrarily.
Rotate speed and can select any-mode, the embodiment of the invention adopts following rotating manner, and the two ends formula of flapping up and down is as follows:
Wherein
α
T0 +Be constant; τ
rBegin to rotate constantly Δ τ
rIt is rotation time.Determine to clap up and down angle of attack
Up, α
DownWith rotation time Δ τ
rJust can determine α '
T0 +τ
rBegin to rotate the moment and Δ τ
rRotation time length can be selected arbitrarily.The angle of attack size of flapping up and down can be selected arbitrarily.
This example selects parameter as follows: τ
c=8.42, Δ τ
t=0.1 τ
c, Δ τ
r=0.32 τ
c, the argument of flapping Φ=160 °, α
Up=α
Down=40 °, τ
cFor flapping the cycle.
To the present invention's three kinds of mode of motion of mode of flapping: leading, symmetry and lagging behind, carry out numerical modelling, and its mechanism that produces high aerodynamic lift is carried out analytical investigation.Fig. 9 and Figure 10 are the present invention flap mode three kinds of mode numerical modellings lift coefficient and drag coefficient Changing Pattern.Contrast Fig. 5 characteristics of motion is analyzed result of calculation.
Symmetry mode, lift coefficient and drag coefficient change comparatively mild, except the intermediary aerodynamic coefficient platform of flapping, have one than high lift peak value and less resistance peak value in the incipient stage of flapping up and down, and ending phase rises drag coefficient and all begins to descend.Symmetrical mode is flapped and the rotational angular velocity change curve among contrast Fig. 5, fast accelerated movement of the incipient stage of flapping, and the angle of attack changes to 40 ° of sharp angles of attack of maintenance from 0 ° simultaneously increases.Cooperate under the fast pull-up effect of the sharp angle of attack in fast acceleration effect, rise drag coefficient and peak value occurs; The ending phase fast retarding efffect of the wing of flapping cooperates the sharp angle of attack to reduce to cause aerodynamic coefficient to descend rapidly from 40 ° to 0 °; The angles of attack such as the intermediary wing maintenance constant speed of flapping are flapped, and this stage nose of wing volute becomes, development is stayed the whirlpool until forming stable leading edge.Stable lift coefficient platform occurs owing to postpone the effect of stall mechanism, produce aerodynamic force contribution of paramount importance.Summing up symmetrical mode high lift mechanism is: the angles of attack such as constant speed are flapped and are postponed the stall effect to high pneumatic benefit generation most critical of the wing of flapping and main contribution.The fast acceleration effect of beginning of flapping cooperates sharp angle of attack increase generation to rise the resistance peak value.The ending phase of flapping in addition retarding efffect cooperates the sharp angle of attack to reduce, and under the effect of gas inertia effect, causes to rise drag coefficient decline.
With symmetrical mode relatively, the leading mode angle of attack such as intermediary constant speed that keeps flapping is flapped and is postponed the aerodynamic coefficient platform that the stall effect forms.But because rotation phase in advance in flapping 8%, causes the aerodynamic coefficient platform to finish in advance to begin to descend.Big negative lift peak value appears in lift coefficient, and the drag coefficient fluctuation descends, and occurs and the wing of the flapping identical positive thrust of direction of flapping.This is that the angle of attack rotates in the process because constant speed is flapped, and when the angle of attack is an acute angle when 40 ° become 0 °, can cause lift coefficient and drag coefficient to reduce simultaneously.The angle of attack further is reduced to negative, becomes-15 ° from 0 °, and lift coefficient further descends, and drag coefficient then can increase with negative angle of attack.The angle of attack continues to become-29 ° of stages from-15 ° subsequently, flapping to slow down and cooperate the negative sharp angle of attack, flaps the wing around under the effect of gas inertia power, and lower aerofoil pressure increases, and top airfoil pressure reduces, and lift coefficient increases sharply.This moment, gas inertia power began the deceleration wing is produced the thrust of pointing to sense of motion, caused drag coefficient to descend rapidly, and at τ/τ
c=0.474～0.5 scope occurs and the wing identical positive thrust of direction of flapping.Next flapping enters reverse acceleration phase, and the angle of attack is just becoming and continuation is increased to 40 ° from 29 °.The initial angle of attack 0 ° during much larger than symmetrical mode, thus this stage occur more than the high a lot of drag coefficient peak values that rise of symmetrical mode.But symmetrical relatively mode, leading mode average lift coefficient descends, and sees Table 1.
The part that occupies main and key factor in the hysteresis mode aerodynamic coefficient Changing Pattern remains the angles of attack such as intermediary constant speed of flapping up and down and flaps and postpone the high aerodynamic coefficient platform of stall mechanism formation.Opposite with leading mode reason, the time that this aerodynamic force platform descends rapidly approximately lags behind symmetrical 8% cycle of mode.Different with leading mode with symmetry, because hysteresiss that rotatablely move, during the fast accelerated movement of the beginning of flapping, the wing angle of attack is for bearing acute angle, so can produce a high negative lift peak value and resistance peak value.Along with negative angle of attack is reduced to 0 ° rapidly, negative lift coefficient peak value and drag coefficient peak value descend rapidly.Next the wing of flapping enters constant speed flaps the stage, and the angle of attack is increased to 40 ° from 0 ° and does the pull-up campaign, because the initial angle of attack is little, and it is longer to rotate pick-up time, only produce to rise the resistance peak value very for a short time, and smooth transition is to the angles of attack such as the constant speed delay stall condition of flapping.
Flap mode and fruit bat of the present invention flapped the mode aerodynamic characteristic relatively.
Figure 11 and Figure 12 are the fruit bat non-permanent aerodynamic coefficient change curve of mode of flapping, associative list 1, flap mode and the existing fruit bat wing more of the present invention mode aerodynamic characteristic difference of flapping:
The lift coefficient curve: 1, partly flap the intermediary, the angles of attack such as constant speed are flapped and are postponed the high non-permanent aerodynamic lift platform that the stall effect produces and still keep, and more steady smooth.Especially be greatly improved in hysteresis mode, flapped two ends acceleration and retarding efffect influence and weaken; 2, the first aerodynamic lift peak value increases to some extent; 3, flap ending phase owing to the rotating manner difference of taking, the second aerodynamic lift peak value disappears.Comprehensive 3 factors are compared with the fruit bat pattern of flapping, and the average lift coefficient of newly flapping is changed to: leading pattern descends-20.8%, symmetric pattern increases by 5.3%, hysteresis mode increases by 45.3%, has greatly improved the lift coefficient of hysteresis mode, and the average lift coefficient gap is significantly dwindled between different mode.
The drag coefficient curve: 1, the drag coefficient peak value significantly descends, and maxim is reduced to fruit bat and flapped the mode maxim below half; 2, the second drag coefficient peak value is owing to the change of rotating manner disappears; 3, the drag coefficient platform all shortens dramatically under the lead and lag pattern than long except still keeping under symmetric pattern.Leading pattern and hysteresis mode reduce to occur low resistance coefficient district at the flap rear portion and the anterior because angle of attack respectively; 4, descend slightly to the hysteresis mode average resistance coefficient from leading pattern, change little.The mode of newly flapping is that average resistance coefficient reduces greatly with the most significant variation of mode of flapping of the fruit bat wing: leading pattern average resistance coefficient descends-41.37%, and symmetric pattern descends-36.6%, and hysteresis mode descends-41.9%.
The existing fruit bat of table 1 mode and the present invention mode of flapping of flapping, the difference mode of flapping on average rises drag coefficient and 1ift-drag ratio
| The pattern of flapping | In advance | Symmetry | Lag behind |
| The fruit bat C that flaps L(average) | ??1.959566 | ??1.787183 | ??0.77392 |
| The present invention claps C L(average) | ??1.551128 | ??1.881962 | ??1.12484 |
| The fruit bat C that flaps D(average) | ??2.997 | ??2.745 | ??2.923 |
| The present invention claps C D(average) | ??1.757 | ??1.740 | ??1.697 |
| The fruit bat C that flaps L/C D | ??0.6538 | ??0.6511 | ??0.2648 |
| The present invention C that flaps L/C D | ??0.8828 | ??1.0816 | ??0.6628 |
Annotate: drag coefficient adopts the absolute value integral mean.
These differences are because in the mode of flapping of the present invention, and flap the up and down quick pull-up campaign of the two ends angle of attack of the fruit bat wing is replaced by reciprocal fast rotational.Though lost the fruit bat wing mode second non-steady lift coefficient peak value of flapping, but turn over motion on also having weakened simultaneously suddenly to the constant speed adverse effect that the intermediary may cause of flapping, it is more steady that the non-permanent aerodynamic coefficient in flow field is changed in time, and the first lift peak value is increased to some extent.Hysteresis mode average lift coefficient is greatly increased.
Of paramount importance is the mode of newly flapping, keep on the high aerodynamic lift basis making full use of the insect non-permanent high lift mechanism of the wing of flapping, owing to removed the huge disturbance that the fast pull-up campaign of the two ends angle of attack stream field structure of flapping causes, can reduce average resistance coefficient greatly, improve average 1ift-drag ratio: leading pattern improves 35.%, symmetric pattern improves 66.1%, and hysteresis mode improves 150.%.Thereby when obtaining quite average aerodynamic lift coefficient, reduce and be used to overcome the mechanical energy that resistance consumes of flapping, improve mechanical efficiency.
Under the symmetric pattern, contrast flap mode and fruit bat of the present invention flap mode flap the wing along exhibition to vorticity lines such as the long cross sections of distance wing root 60% exhibition, see Figure 13.Provide three τ/τ constantly among the figure
c=-0.057,0.014 and 0.394, laying respectively at flaps finishes to slow down, and begins acceleration and middle constant speed and flaps the stage.Can find interesting phenomenon, at each constantly, the relative distance of two kinds of modes of the flapping trailing vortex that splits away off from the wing of flapping and the wings of flapping changes not remarkable, and the variation of both relative positions clearly is because the attitude difference of the wing of flapping causes, and sees τ/τ c=-0.057 and at 0.014 o'clock.When the attitude of the wing of flapping is identical, τ/τ c=0.394, the vortex structure in flow field is also closely similar.In conjunction with the analysis of front, show that the variation of the two ends rotation direction of flapping just causes the wing attitude of flapping to change, thereby cause two kinds of significant differences on the mode aerodynamic characteristic of flapping non-permanent aerodynamic force and average aerodynamic force.
By last surface analysis, obtain as drawing a conclusion:
(1) compare with the existing fruit bat wing mode of flapping, the present invention's mode of flapping has sufficiently and reasonably been utilized the fruit bat wing high lift mechanism of flapping: postpone stall mechanism and quicken fast reduction gear mechanism soon.
(2) when guaranteeing to obtain high aerodynamic lift, greatly reduce the non-permanent aerodynamic drag of the wing of flapping, the very effective 1ift-drag ratio that has improved the wing of flapping: leading pattern improves 35.%, and symmetric pattern improves 66.1%, and hysteresis mode improves 150.%.Thereby when obtaining cooresponding average lift coefficient, reduce and be used to overcome the mechanical energy consumption of resistance of flapping, improve mechanical efficiency.
(3) the present invention's mode of flapping has greatly improved the flap aerodynamic characteristic of mode hysteresis mode of traditional fruit bat wing, has relaxed the flap greatest differences of aerodynamic characteristic between three kinds of mode of motioies of mode of traditional fruit bat wing.
(4) for the minute vehicle of small scale, the thin flat plate wing is more practical.The mode of newly flapping that this front and rear edge of the present invention replaces exactly is well suited for being applied to the thin plate wing.And this mode of flapping makes and applies camber to improve 1ift-drag ratio on thin flat plate is flapped the wing, becomes significant thing, and for traditional fruit bat mode of flapping, it is postiche doing like this.
(5) on the other hand, consider that the mode of newly flapping is also easier to be realized in the minute vehicle design from the angle that mechanism realizes.
At last, on above numerical simulation and the basis researched and analysed, naturally understand statement into question: since the mode of newly flapping has so big advantage and benefit, why not do insect and birds adopt the described mode of newly flapping of this section? this is a complicated problems, must be from biology, physiology, multi-angles such as anatomy and biological evolution are explained.A kind of explanation more intuitively be, great majority adopt the structure of the wing of the insect of fruit bat wing flying methods or birds, wing film or feather, and wing arteries and veins or bone have determined the flying method that they can't take this paper to introduce.But the structure design for minute vehicle on the contrary can be not limited to these problems.
Claims (10)
1, the bionic flapping method that is used for minute vehicle is characterized in that comprising: be divided into arsis stage and following bat stage, the arsis stage is divided into three parts:
(1) wing of flapping turns under rotating the arsis incipient stage, and flapping simultaneously accelerates to the arsis angle of attack and arsis speed;
(2) wing of flapping keeps the arsis angle of attack and arsis speed constant substantially the arsis intermediary;
(3) the arsis ending phase wing of flapping begins to rotate from the arsis angle of attack in arsis intermediary and turns over the deceleration of flapping simultaneously;
The following bat stage also will be divided into three parts:
(1) clap down the incipient stage wing of flapping and rotate and turn over, flapping simultaneously accelerates to down the angle of attack and the following bat speed of clapping;
(2) clap down the intermediary and flap that to keep clapping down the angle of attack and following bat speed constant substantially for the wing;
(3) clap down the ending phase wing of flapping and under the following bat angle of attack of clapping the intermediary down begins to rotate, turn over the deceleration of flapping simultaneously;
One time arsis becomes one-period with clapping down, and arsis and following bat stage hocket, and the oscillation cycle motion realizes flapping method of the present invention.
2, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the described wing of flapping is the dull and stereotyped wing, or the wing of band camber.
3, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the described wing of flapping is a rigid wings, or flex-wing.
4, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the described arsis angle of attack also can be different with the bat angle of attack can be identical at different cycles down.
5, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: describedly flap the wing with respect to the arsis angle of attack of the working direction of flapping and clap the angle of attack down less than 90 °.
6, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the flapping acceleration of described arsis in the stage is the process from the arsis speed in 0 to arsis intermediary; The arsis speed of slowing down from the arsis intermediary of flapping in described arsis stage reduces to 0 process; The acceleration of flapping in described following bat stage is from 0 process to the following bat speed of clapping the intermediary down; The described deceleration of flapping of clapping ending phase down is the process from the following bat speed to 0 of clapping the intermediary down.
7, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the described upper and lower incipient stage of flapping flap quicken institute's time-consuming and ending phase deceleration institute time-consuming all greater than 0 smaller or equal to four/one-period.
8, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the described two ends of flapping up and down, the wing of flapping rotate required time greater than 0 less than half of the cycle of flapping.
9, the bionic flapping method that is used for minute vehicle according to claim 1, it is characterized in that: described flap up and down incipient stage and ending phase, flap and quicken and the characteristics of motion that meets of slowing down can be to satisfy to quicken the finish time and the cireular frequency time derivative of flapping the zero hour of slowing down is 0 arbitrary function.
10, the bionic flapping method that is used for minute vehicle according to claim 1 is characterized in that: the rule that the described wing upset of flapping is met can be that satisfied upset beginning and rotational angular velocity time finish time inverse are 0 arbitrary function.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109204811A (en) * | 2018-10-10 | 2019-01-15 | 南京航空航天大学 | There is empennage flapping wing aircraft |
| CN110203389A (en) * | 2009-06-05 | 2019-09-06 | 威罗门飞行公司 | Air vehicle flight mechanism and control method |
| CN112660372A (en) * | 2021-01-11 | 2021-04-16 | 北京航空航天大学 | Multi-flapping-wing micro aircraft designed by simulating wild goose knot array and gliding flight |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2581325Y (en) * | 2002-09-04 | 2003-10-22 | 赖金群 | Ornithopter |
| CN2597334Y (en) * | 2002-12-16 | 2004-01-07 | 高沛 | Bionic machine insect flying device |
| CN1182004C (en) * | 2003-03-10 | 2004-12-29 | 东南大学 | Bionic electromagnetically driven flapping wing unit for mini aircraft |
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2005
- 2005-07-07 CN CNB2005100829275A patent/CN100333969C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110203389A (en) * | 2009-06-05 | 2019-09-06 | 威罗门飞行公司 | Air vehicle flight mechanism and control method |
| CN110203389B (en) * | 2009-06-05 | 2023-08-04 | 威罗门飞行公司 | Aircraft flight mechanism and control method |
| CN109204811A (en) * | 2018-10-10 | 2019-01-15 | 南京航空航天大学 | There is empennage flapping wing aircraft |
| CN109204811B (en) * | 2018-10-10 | 2024-03-19 | 南京航空航天大学 | Flapping wing aircraft with tail wing |
| CN112660372A (en) * | 2021-01-11 | 2021-04-16 | 北京航空航天大学 | Multi-flapping-wing micro aircraft designed by simulating wild goose knot array and gliding flight |
| CN112660372B (en) * | 2021-01-11 | 2022-11-08 | 北京航空航天大学 | Multi-flapping-wing micro aircraft designed by simulating wild goose knot array and gliding flight |
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