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  • 标题:Wings with improved aerodynamic characteristics.
  • 作者:Scurtu, Dan ; Ciobanu, Bogdan
  • 期刊名称:Annals of DAAAM & Proceedings
  • 印刷版ISSN:1726-9679
  • 出版年度:2008
  • 期号:January
  • 语种:English
  • 出版社:DAAAM International Vienna
  • 摘要:The paper aims at establishing, in a theoretical and experimental manner, the influence of a q controlled debit jet on its aerodynamic features. The jet is launched through the trailing edge of the lift wing.
  • 关键词:Aerodynamics

Wings with improved aerodynamic characteristics.


Scurtu, Dan ; Ciobanu, Bogdan


1. INTRODUCTION

The paper aims at establishing, in a theoretical and experimental manner, the influence of a q controlled debit jet on its aerodynamic features. The jet is launched through the trailing edge of the lift wing.

The issue was already approached at a theoretical level at the half of the 20th century. (Davidson I.M. 1956) theoretically studies the jet-flaps lift wing. In 1955, Kadasch M. sets a theoretical form of a complex function that describes the fluid movement around a fluid emission lift wing through the trailing edge. (Malavard L. 1956) sets a linear form of functions for the disturbing potential determined by the jet. (Nagy A.B. 1969) extends the theory Kutta-Jukovsky to jet air foils. (Roy M. 1956) sets an expression for the disturbing potential generated by the jet from the trailing edge. (Dumitrescu L. 1957 and Patraulea N. 1961) theoretically set the effect of fluid emission on the lift force. All this research aimed at the plane wing and became less effective along with the development of engines used in aviation engines.

In the context of present energy deficit, we believe it is useful to continue the research applying to the singular wing and the network working wing that applies to axial aeraulic generators.

2. GENERAL CONSIDERATIONS

The lift wing put in a real current fluid generates a lift force [F.sub.L] = [rho]/2 x b x c x [C.sub.L] x [W.sup.2.sub.[infinity]] and a drag force [F.sub.D] = [rho]/2 x b x c x [C.sub.D] x [W.sup.2.sub.[infinity]] in which: [rho]--the density of the fluid current moving around the wing, [C.sub.L]--lift coefficient, CD--the draft coefficient, [W.sub.[infinity]] is the speed of the general current, b the span and c the air foil cord. In practical applications, the lift force [F.sub.L] must be as big as possible, and the drag force [F.sub.D], as small as possible.

In order to achieve this, the lift coefficient values [C.sub.L] must be as big as possible and the values of the drag coefficient [C.sub.D] must be as small as possible.

The paper has in view a physical method that allows the increase of the lift coefficient, at the same time with the decrease of the drag coefficient.

The method consists of the creation of a controlled emission of fluid in the trailing edge of an aerodynamic air foil.

The fluid emission is assimilated to an equally distributed source on the span, figure 1.

[FIGURE 1 OMITTED]

3. MATHEMATICAL MODELLING OF THE MOVEMENT

The study of fluid flow around the solid bodies is based on the theory of potential movements and the use of the custom transformation theory.

The general movement of the fluid around the circle of custom transformation with fluid jet is described by the global complex potential function:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (1)

The lift theoretical coefficient CLT is given by the relation:

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (2)

The theoretical modelling of the flow was made in the following conditions:

--The chosen aerodynamic air foil is type Go593.

--The values of the incidence angle [alpha] [deg] = -6[degrees], -1[degrees], 2[degrees], 4[degrees], 6[degrees], 8[degrees], 10[degrees], 12[degrees], 14[degrees], 16[degrees].

--The q debit [[m.sup.3]/s] of the jet [q.sub.0] = 0; [q.sub.1] = 0.001; [q.sub.2] = 0.002; [q.sub.3] = 0.003; [q.sub.4] = 0.004; [q.sub.5] = 0.005; [q.sub.6] = 0.006.

--[q.sub.0] = 0 stands for the classic aerodynamic air foil (no jet in the trailing edge).

--The speed of the general current [W.sub.[infinity]] = 20 [m/s]; cord c = 0.1 [m]; span b = 0.5 [m].

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Figure 3 present the lift and drag coefficients for Go593 airfoil, without fluid emission, as given in catalogues.

In figure 4, the variations of the theoretical coefficient [C.sub.L] are presented for all the values of q, taking into consideration all the values of the incidence angle [alpha].

4. THE EXPERIMENTAL STUDY OF THE PHENOMENA

We aimed at assessing the lift coefficient [C.sub.L] and the drag coefficient [C.sub.D] for a controlled fluid jet lift wing emitted by the trailing edge, as compared to the classic wing in the same conditions as in theoretical modelling.

The tests were performed on an open circuit aerodynamic tunnel, with continuous speed adjustment in the working chamber and a turbulence degree of 0.006; the aerodynamic balance used for measurements is made up of type FUTEK FBB350 force transducers.

The results of experimental determinations referring to the [C.sub.L] lift coefficient and the drag coefficient [C.sub.D] are shown in figures 5 and 6.

5. CONCLUSIONS ON EXPERIMENTAL DETERMINATIONS

--The increase of the lift coefficient depends on the q debit jet evacuated through the trailing edge.

--The values of lift coefficient for the wing with jets emitted through the trailing edge are bigger than those for the classic wing up to 40%.

--The increase of the lift coefficient for the jet wing is determined by circulation [??] growth.

--The values of drag coefficient for the fluid jet wing are smaller than the values determined for the classic wing.

--For values of the incidence angle a from 0[degrees] to 14[degrees], the drag coefficient values are negative. In this area of incidence angles, the lift wing incidence shows a propulsive character.

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

The look forward of presented studies refers at:

--Theoretical and experimental studies about flow in laminar layer.

--Establish of a method to draw an air foil for an imposed pressure (velocity) distribution.

--Experimental studies of an air foils network with fluid emission through trailing edge.

6. REFERENCES

Davidson, I.M. (1956). The Jet-Flap, Journal of the Royal Aerodynamic Society, London

Dumitrescu, L. (1957). Determinarea efectului de ejectie la profilele cu volet fluid (Determination of emission effect for airfoils with fluid volet), Revista studii si Cercetari de Mecanica aplicata, tom VIII

Kadasch, M. (1955). Theorie des profiles avec soufflage au bord de fuitte (Theory of airfoils with fluid emission through trailing edge), Bul. De la Soc. Francaise des Mecaniciens, nr. 18

Malavard, L. (1956). Sur une theorie lineare du soufflage au bord de fuitte d'un profile d'aille (About a lineare theory of emission through the trailing edge of an airfoil), Comptes Rendus nr. 242, Paris

Nagy, A.B. (1969). Asupra teoriei Kutta-Jukowski la profilele cu jet (About Kutta-Jukowski theory of airfoils with jet), Studii matematice, Ed. Acad. Romane

Patraulea, N. (1961). Aripi cu jet in bordul de fuga (Wings with jets through trailing edge), Studii si cercetari de mecanica aplicata nr. 5

Roy, M. (1956). Theorie d'un profil d'aille a jet (Theory of a jet-wing), Comptes Rendus nr. 244, Paris
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