Effect of a fuselage on delta wing vortex breakdown

Straka, W. A.; Hemsch, Michael J.

doi:10.2514/3.46600

Cited by 24 publications

(13 citation statements)

References 5 publications

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“…8 Experimental results for a 69.33-degdelta-wing-body con gurationdemonstrated that the centerbody promoted vortex breakdown. 9 This could be explained by the body-induced camber effect, 8,10 which according to experimental results for the effect of static camber, 11 would have promoted breakdown, in agreement with the experimental results. Figure 3 shows con gurational details of the models giving the results in Fig.…”

Section: Introductionsupporting

confidence: 80%

Flow Complexities of Slender Wing Rock

Ericsson¹

2000

Journal of Aircraft

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IntroductionM ILITARY design trends toward the use of unmanned, nless aircraft 1 have renewed interest in the unsteady aerodynamics of slender wing rock. One important aspect of the problem of wing rock control is the potential impact of typical con gurational details on delta-wing aircraft, such as the presence of a centerbody. Early experimental results for a sharp-edged 80-deg delta wing indicated that breakdown of the leading-edgevortices played a role 2,3 ( Fig. 1). It could be shown that rather than being the cause of the wing rock problem, the breakdown phenomenon limited the growth of the limit-cycle amplitude. 4 By the consideration of the effect of the roll-induced sideslip on the effective leading-edge sweep of the windward (dipping) wing-half, an upper limit for the limit-cycle amplitude could be determined. 5,6 The measured start of wing rock (Fig. 1a) is in good agreement with the prediction 7 that, for zero bearing friction, loss of roll damping should occur at a¸20 deg (Fig. 2). Bearing friction caused the delay to a = 25 deg of the loss of roll damping in the test of a pure delta-wing model 3 (Fig. 1a). It will be shown that the earlier start of wing rock for the other model 3 was caused by the presence of a centerbody or fuselage.As even unmanned combat aircraft are likely to have a fuselage or centerbody of some kind, it is important to know that the effect of a centerbodyon delta-wingaerodynamicscan be large. 8 Experimental results for a 69.33-degdelta-wing-body con gurationdemonstrated that the centerbody promoted vortex breakdown. 9 This could be explained by the body-induced camber effect, 8,10 which according to experimental results for the effect of static camber, 11 would have promoted breakdown, in agreement with the experimental results. Figure 3 shows con gurational details of the models giving the results in Fig. 1. Whereas the Langley model 2 behaves essentially as a pure, sharp-edgeddelta wing, the other model 3 has a centerbody. Because of its bluntness, 12 it behaves as a cylindricalcenterbody, 9, 10 promoting vortex breakdown, thereby causing a reduction of the maximum wing rock amplitude. The earlier loss of roll damping, before the predictedvalue 7 a ¼ 20 deg (Fig. 2), could also have been caused by the presence of the centerbody.By limiting the wing area, the centerbody acts to increase the effective leading-edge sweep, thereby causing earlier loss of roll damping.The experimental results 13 in Fig. 4 show that when a pointed ogive-cylinder centerbody, similar to the one used in Ref. 9, is moved aft to start behind the wing apex, as in the case of the extensively tested 65-deg delta-wing-body con guration, 13 instead of promoting breakdown, the body delayed vortex breakdown to occur 30% or more aft of the measured position for a pure 65-deg deltawing. 14 It is described in Ref. 5 how this is the expected result when the pointed ogive-cylinder body is moved aft, as shown in Fig. 4, Presented as Paper 99-0141 at a) Measured wing rock amplitude 2;3 b) Flow visualization of vorte...

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Section: Introductionsupporting

confidence: 80%

Flow Complexities of Slender Wing Rock

Ericsson¹

2000

Journal of Aircraft

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“…However, Guglieri and Quagliotti [4] observed that the presence of a fuselage-like structure under the lower surface of the delta wing influenced the position of vortex breakdown to move upstream as much as 20% chord for a sharp-edged 65-deg delta wing. Straka and Hemsch [12] also found that adding a centerbody to the delta wing planform dramatically promoted the onset and chordwise progression of vortex breakdown (specifically, at an 8-deg lower angle of attack with fuselage than without). Straka and Hemsch's experimental model was a flat-plate delta wing attached to the fuselage of a pointed tangent-ogive front-body and a 1.5-inch diameter cylindrical aft-body.…”

Section: Introductionmentioning

confidence: 91%

“…Straka and Hemsch [12] showed that adding a centerbody to the 69.3-deg delta wing dramatically promoted the vortex breakdown position. For example, at a 27.5-deg angle of attack the vortex breakdown position moved from about 85% to 30% chord by adding the centerbody.…”

Section: Piv Measurement and Reynolds Number Effectmentioning

confidence: 98%

“…For example, at a 27.5-deg angle of attack the vortex breakdown position moved from about 85% to 30% chord by adding the centerbody. Ericsson [1] suggested that the pointed ogive centerbody positioned ahead of the wing apex induced upwash along the leading edge of the wing and that this resulted in promotion of the vortex breakdown position in Straka and Hemsch [12]. The present study of performing simultaneous visualization, and PIV measurements of the flow field and the wing-surface pressure measurement for wide range of flow Reynolds number (from 4.4 × 10 5 to 1.76 × 10 6 ) suggests that the profound effect of the centerbody on the vortex breakdown position in Straka and Hemsch did not solely come from its presence and position.…”

Section: Piv Measurement and Reynolds Number Effectmentioning

confidence: 99%

“…He suggested that the pointed ogive centerbody positioned ahead of the wing apex in Straka and Hemsch [12] induced upwash along the leading edge and generated a negative camber effect, which would result in promotion of the vortex breakdown. However, the centerbody in Hanff and Jenkins, where the pointed ogival portion of the centerbody was located behind the wing apex, generated a positive wing-camber effect which delayed the vortex breakdown.…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Effect of a centerbody on the vortex flow of a double-delta wing with leading edge extension

Sohn¹,

Chang²

2010

Aerospace Science and Technology

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Surface pressure model for simple delta wings at high angles of attack

Pashilkar

2001

Sadhana

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A new aerodynamic modelling approach is proposed for the longitudinal static characteristics of a simple delta wing. It captures the static variation of normal force and pitching moment characteristics throughout the angle of attack range. The pressure model is based on parametrizing the surface pressure distribution on a simple delta wing. The model is then extended to a wing/body combination where body-alone data are also available. The model is shown to be simple and consistent with experimental data. The pressure model can be used as a first approximation for the load estimation on the delta wing at high angles of attack.

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Effect of a fuselage on delta wing vortex breakdown

Cited by 24 publications

References 5 publications

Flow Complexities of Slender Wing Rock

Flow Complexities of Slender Wing Rock

Effect of a centerbody on the vortex flow of a double-delta wing with leading edge extension

Surface pressure model for simple delta wings at high angles of attack

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