Drag reduction factor due to ground effect

A numerical investigation has been conducted to analyze the influence of the dynamic ground effect on the aerodynamic characteristics of a rectangular wing. The numerical model is based on a three-dimensional panel method and the ground effect is analyzed using the method of images. Before simulating the wing approaching the ground, the model developed was tested assuming fixed height and the results were examined by comparison to analytical and numerical results showing a good agreement. Then, the dynamic ground effect was investigated for two flight conditions: constant rate of descent and varying rate of descent. The results obtained by dynamic ground effect and those ones computed using static ground effect were compared evidencing that the static ground effect underpredicts the lift coefficient and overpredicts the induced drag coefficient. In addition, for these flight conditions, the lift coefficient increases when non-dimensional height decreases observing that it is more significant for a constant value of rate of descent, and the induced drag coefficient decreases while non-dimensional height reduces evidencing a significant decrease for a varying rate of descent. Finally, the effect of the flight path angle was evaluated demonstrating that the lift and the induced drag coefficients decrease with more negative flight path.

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“…(18) and (19), respectively, and the values obtained using ATHENA, PAN AIR and CMARC presented in Ref. [12].…”

Section: Case Studymentioning

confidence: 97%

“…The results obtained were compared with the analytical expressions to estimate the drag reduction factor (G) presented by Suh and Ostowari 19 and Laitone,20 which are shown in Eqs. (18) and (19), respectively, and the values obtained using ATHENA, PAN AIR and CMARC presented in Ref.…”

Section: Case Studymentioning

confidence: 98%

Linear Computational Fluid Dynamic Analysis of Dynamic Ground Effect of a Wing in Sink and Flare Maneuvers

Quijada

Boschetti

2015

AIAA Atmospheric Flight Mechanics Conference

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“…There are different closed-form relations in the literature to estimate the drag reduction factor, and these are mainly a function of H/b. For wings in ground effect, the relations presented from Suh and Ostowari, 10 and Laitone 11 are chosen and shown in Eqs. (2) and (3), respectively.…”

Section: Ground Effectmentioning

confidence: 99%

Dynamic Ground Effect on the Aerodynamic Coefficients of a Wing using a Panel Method

Boschetti

Quijada

Cárdenas

2016

AIAA Atmospheric Flight Mechanics Conference

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A numerical investigation has been developed to evaluate the influence of dynamic ground effect on the aerodynamic coefficients of a wing using a panel method. This simulates unsteady flow by the time-marching method with a deformable free wake. The image method is used to model ground effect. Lift, induced drag, and pitching moment coefficients were obtained considering fixed height above the ground (static ground effect) and the wing in sink and flare maneuvers (dynamic ground effect). The results at static ground effect were compared with analytical and numerical results in order to verify and validate the created panel code, and they are acceptable. Lift and the absolute value of the pitching moment coefficients increase and the induced drag coefficient decreases as the height diminishes. Although the trends in static and dynamic ground effect are similar, the aerodynamic coefficients achieved in static ground effect are less affected than those ones calculated by simulations of the wing approaching the ground. Linear models of the wing in ground effect were developed by using the data of constant rate of descent and flare maneuvers. The sink rate produces significant variations in the aerodynamic coefficients of a wing. Nomenclature b= wingspan CL, CD, CM = lift, drag, and pitching moment coefficients CL0, CD0, CM0 = lift, drag, and pitching moment coefficients at zero angle of attack CLq, CDq, CMq = variation of lift, drag, and pitching moment coefficients with pitch rate CLh, CDh, CMh = variation of lift, drag, and pitching moment coefficients with c H CLα, CDα, CMα = lift, drag, and pitching moment slopes

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“…The drag reduction factor (G) is the relation between the induced drag coefficient in ground effect and that one at free flight, and there are many closed-form relations in the literature to estimate it. 2,3 Wind tunnel testing carried out on wings of aspect ratio equal to 3.46 and 5.18 shows an increase in lift (including the maximum lift coefficient) with an important reduction of induced drag and a systematic increase of the viscous drag due to ground effect respect to free flight data. 4 Phillips and Hunsaker 5 proposed an analytical expression for estimating the change of lift in ground effect for unswept, untwisted wings without dihedral.…”

Section: Introductionmentioning

confidence: 98%

Dependence of the Flight-path on the Aerodynamic Characteristics of Rectangular Wings due to Dynamic Ground Effect

Merkl

Boschetti

Cárdenas

2019

AIAA Scitech 2019 Forum

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The objective of this paper is to evaluate the dependence of the flight-path when height changes as function of time on the aerodynamic characteristics of single rectangular wings with aspect ratios between 4 and 12 due to dynamic ground effect using an unsteady vortexring panel code, which uses a time-stepping method and the image method to simulate climb and sink maneuvers with a free wake. It is observed that each maneuver has different effects on lift, drag, and pitching moment coefficients. For a constant rate of descent and climb maneuvers, the flight path angle has an important impact over the results increasing the lift and induced drag coefficients and decreasing the pitching moment coefficient as the flight path angle decreases because the flight path angle is linked to the effective angle of attack. In contrast, no evident relation is appreciated between the static and dynamic ground effect in flare. Lift and induced drag spanwise distributions are also considerably affected by the specific maneuver. Finally, the nondimensional h derivatives are related to the flight path of the wing in ground effect. Nomenclature b = wingspan CL, CD, CM = lift, drag, and pitching moment coefficients CL0, CD0, CM0 = lift, drag, and pitching moment coefficients at zero angle of attack CLq, CDq, CMq = variation of lift, drag, and pitching moment coefficients with pitch rate CLh, CDh, CMh = variation of lift, drag, and pitching moment coefficients with nondimensional height CLα, CDα, CMα = lift, drag, and pitching moment slopes

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Drag reduction factor due to ground effect

Cited by 28 publications

References 1 publication

Linear Computational Fluid Dynamic Analysis of Dynamic Ground Effect of a Wing in Sink and Flare Maneuvers

Linear Computational Fluid Dynamic Analysis of Dynamic Ground Effect of a Wing in Sink and Flare Maneuvers

Dynamic Ground Effect on the Aerodynamic Coefficients of a Wing using a Panel Method

Dependence of the Flight-path on the Aerodynamic Characteristics of Rectangular Wings due to Dynamic Ground Effect

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