CN104494842B - Rising wingtip design method - Google Patents

Abstract

The invention belongs to the field of aircraft pneumatic layout design, and relates to a rising wingtip design method. The method comprises the steps of: building a vorticity calculating method for reducing the wingtip vortex streaming by using the wingtip reverse streaming vortex; designing a rising wingtip to partially counteract the circular reactor of the wingtip vortex to reduce the loss of wingtip three-dimensional streaming so as to achieve the purposes of reducing the whole aircraft resistance and improving the whole aircraft lift; calculating the position and the feature size of a space-inclined curved surface through the fluid mechanics to perform optimal adjustment and selection; and further performing the verification and the optimization for the design through a wind tunnel test. The rising wingtip design method creatively builds the resistance-reducing and lift-improving design principle of the wingtip reverse streaming vortex, and initiates the rising wingtip design principle and method capable of improving the lift while reducing the structural weight and simplifying the structural design.

Description

A kind of lift-rising tip design method

Technical field

The invention belongs to civil aircraft aerodynamic arrangement design field, is related to a kind of lift-rising tip design method.

Background technology

During aircraft aerodynamic arrangement designs engineers all the time constantly for improve lift reduce flight resistance and put forth energy Bucket.Actual airplane is limited by spanwise extent, and in the wing wing ending position Three dimensional Flow is produced, and makes the lift of true wing obvious Less than dimensional airfoil.In order to reduce, the resistance that wingtip vortex causes increases and lift is reduced, and pneumatic design engineers design is various Winglet, and achieve positive effect.

In modern aircraft design, winglet is most of all to stretch out a little fin obliquely upward as spy in host wing outer end Point, major technique handss principle are all to stop and reduce the generation of wingtip vortex, play the identical effect of increase wing length.Such wing Slightly smaller wing effect is obvious, but while also increase weight, increases manufacturing process complexity.

The content of the invention

The technical problem to be solved is：By setting up a kind of brand-new lift-rising principle, there is provided a kind of lift-rising wing Sharp method for designing, to increase airplane ascensional force, reduce resistance, while simplifying manufacturing process, mitigating weight.

The technical scheme is that：A kind of lift-rising tip design method, it is characterized by methods described is comprised the steps of：

Step one, foundation reversely streams whirlpool to reduce the vorticity computational methods that wingtip vortex streams using wing tip, and its formula is：

Γ_Always=Γ_{Wing tip}-Γ_Lift-rising

In formula, Γ_AlwaysIt is that total wing tip streams vorticity, Γ after lift-rising tip design_{Wing tip}For the wing tip state that commonly smoothly transits Under wing tip stream vorticity, Γ_Lift-risingIt is reversely to stream vorticity through what this lift-rising tip design method was obtained；

Step 2, designs lift-rising wing tip, the circular rector partial offset of wingtip vortex is enable, so as to reduce wing tip Three dimensional Flow Loss, reaches the purpose for reducing the full machine lift of full machine resistance increase, including：

2.1) according to the vorticity of streaming of airplane design flight speed and lift-rising wing tip, the average angle of sweep of wing tip is chosen, The size of sweepback angle is between 5 °～30 °；

2.2) according to the concrete aerofoil profile feature of aircraft wing, relative thickness and camber and the average angle of sweep of wing tip, using sky Between tilting curved surface clip one section of wing tip, becoming can produce the lift-rising wing tip for reversely streaming whirlpool；

Step 3, by hydrodynamics method to step 2.2) in the tilting curved surface in space position and characteristic size enter Row is optimized and revised and selected；

Step 4, further carries out verifying and preferred by wind tunnel test to design.

The beneficial effects of the present invention is：By the present invention, initiative establishes wing tip reversely streams whirlpool drag reduction lift-rising and sets Meter principle, having initiated can also increase the lift-rising tip design principle of lift while mitigating construction weight, simplify structure design And method；There is provided one kind improves wing tip around stream mode, and so as to increase lift resistance is reduced, but does not increase even mitigation wing Weight, does not increase the method for designing of airfoil member manufacturing process complexity；Machine can guarantee that by the winglet of present invention design Wing area is constant, and the effect of drag reduction lift-rising is substantially played in the case of reducing wing tip weight.

Description of the drawings

Fig. 1 is three-dimension curved surface beveling lift-rising wingtip vortex inventive principle figure.

Fig. 2 is three-dimension curved surface beveling lift-rising wing tip geometry schematic diagram.

Fig. 3 is three-dimension curved surface beveling lift-rising wing tip geometry schematic diagram.

Fig. 4 is smoothly transit common wing tip and three-dimension curved surface beveling lift-rising wing tip lift coefficient contrast figure line (wind tunnel test As a result).

Fig. 5 is smoothly transit common wing tip and three-dimension curved surface beveling lift-rising wing tip resistance coefficient contrast figure line (wind tunnel test As a result).

Specific embodiment

Below by specific embodiment and combine accompanying drawing the present invention is described in further detail.

The step of the present invention includes：

Step one, mainly stopped that wingtip vortex streamed difference with former lift-rising tip design with winglet, initially set up one Kind brand-new reversely streams whirlpool to reduce the theory that wingtip vortex streams using wing tip.New vorticity computing formula is：

Γ_Always=Γ_{Wing tip}-Γ_Lift-rising

The circular rector of wingtip vortex is able to partial offset after special formed lift-rising tip design, three-dimensional so as to reduce wing tip The loss streamed, reaches the purpose for reducing the full machine lift of full machine resistance increase；

Step 2, according to airplane design flight M numbers the appropriate average angle of sweep of wing tip, the size of sweepback angle are chosen About between 5 °～30 °；

Step 3. according to the concrete aerofoil profile feature of aircraft wing, relative thickness and camber and the average angle of sweep design of wing tip Corresponding wing tip intercepts scheme, the tilting round platform curved surface in such as space, waist drum curved surface etc..

Step 4, calculates the position to beveling curved surface and characteristic size is optimized adjustment and selection, Ke Yiti by CFD It is alternative for several preferred versions；

Step 5, further carries out verifying and preferred by wind tunnel test to design.

It is presented herein below using the embodiment of lift-rising tip design method of the present invention.

In the design of RX1P two-seaters ultra light aircraft, three-dimension curved surface beveling lift-rising tip design is employed.

RX1P two-seaters ultra light aircraft be high mounted wing normal arrangement, using etc. straight wing design, wing area 11.42m2, Wing span 9263mm, average air power chord length is 1250mm.With certain established angle and the upper counterangle.Wing tip carries one Fixed sweepback.Under normal circumstances transverse cross-sectional shape is smoothly transitted using half-round curve at wing tip.

Using the principle and technology of this invention, in the situation for not changing wing planform and every basic parameter size Under, drag reduction lift-rising optimization design is carried out to wing tip.The outer bottom of former wing tip is chamfer using three-dimensional optimized curved surface, is made around miscarriage The reverse vorticity of life, so as to reach drag reduction lift-rising, while mitigating the effect of construction weight.Specific design step is as follows：

Step one, RX1P two-seater ultra light aircrafts design cruising speed is 216 kilometers/hour, using straight wing, aerofoil profile For NASA3010, confirmation can design lift-rising wing tip carry out drag reduction lift-rising to full machine using this method；

Step 2, designs flight M numbers and chooses the appropriate average angle of sweep of wing tip according to RX1P two-seaters ultra light aircraft, About between 5 °～30 °, the average angle of sweep desired value of this example design wing tip is 20 ° to the size of sweepback angle；

Step 3. according to the concrete aerofoil profile feature of RX1P two-seater ultra light aircraft wings, relative thickness and camber and wing tip Average angle of sweep designs corresponding wing tip and intercepts scheme, using the round platform curved surface that space is tilting, wing tip is intercepted, round platform Axis of small circle 400mm, axis of great circle 480mm, the high 2089mm of round platform, with certain space angle (direction vector is 0.98, 0.028,0.196) intercept wing tip.

Step 4, by carrying out CFD calculating to RX1P two-seaters ultra light aircraft, the beveling wing tip scheme obtained in step 3 There is significant drag reduction lift-rising effect, and scheme is optimized adjustment and selects to the position and characteristic size that chamfer curved surface based on it Select, there is provided 2 alternatives；

Step 5, is further verified by wind tunnel test to design, confirms that the method for designing is effective, hence it is evident that carry The aeroperformance of RX1P two-seater ultra light aircrafts is risen.

Be given below in conjunction with the accompanying drawings and further illustrate.Fig. 1 and Fig. 2,3 sets forth three-dimension curved surface beveling lift-rising wingtip vortex Schematic diagram and three-dimension curved surface beveling lift-rising wing tip geometry schematic diagram.

Fig. 4 and Fig. 5 sets forth the common wing tip that smoothly transits and chamfer lift-rising wing tip lift coefficient and resistance with three-dimension curved surface Force coefficient contrast figure line (results of wind tunnel).

From on contrast figure line as can be seen that maximum lift coefficient improves 5%.The resistance of the angle of attack common sweepback wing tip when being 0 ° Coefficient is 0.03375, and the resistance coefficient of sharp sweepback wing tip is 0.02906, and resistance coefficient reduces by 0.005, reduces by 1/6th, subtracts Resistance effect is fine.The lift increment being converted under identical resistance, lift increase about 17% under cruising speed.The angle of attack is close 13 ° Resistance increases very little during maximum lift state, and the angle of attack is further added by resistance and is significantly increased, but now resistance has not been mainly to ask Topic.

Three-dimension curved surface beveling lift-rising wing tip has obvious drag reduction lift-rising effect, can substantially reduce cruise drag raising and most rise higher Power.

Claims (1)

1. a kind of lift-rising tip design method, it is characterized by methods described is comprised the steps of：

Step one, foundation reversely streams whirlpool to reduce the vorticity computational methods that wingtip vortex streams using wing tip, and its formula is：

Г_Always=Г_{Wing tip}-Г_Lift-rising

In formula, Г_AlwaysIt is that total wing tip streams vorticity, Г after lift-rising tip design_{Wing tip}Commonly to smoothly transit under wing tip state Wing tip streams vorticity, Г_Lift-risingIt is reversely to stream vorticity through what this lift-rising tip design method was obtained；

Step 2, designs lift-rising wing tip, the circular rector partial offset of wingtip vortex is enable, so as to reduce the damage of wing tip Three dimensional Flow Lose, reach the purpose for reducing the full machine lift of full machine resistance increase, including：

2.1) according to the vorticity of streaming of airplane design flight speed and lift-rising wing tip, the average angle of sweep of wing tip, sweepback are chosen The size of angle is between 5 °～30 °；

2.2) according to the concrete aerofoil profile feature of aircraft wing, relative thickness and camber and the average angle of sweep of wing tip, using Space Oblique The curved surface put clips one section of wing tip, and becoming can produce the lift-rising wing tip for reversely streaming whirlpool；

Step 3, by hydrodynamics method to step 2.2) in the tilting curved surface in space position and characteristic size carry out it is excellent Change adjustment and select；

Step 4, further carries out verifying and preferred by wind tunnel test to design.