Ground Effect on the Vortex Flow and Aerodynamics of a Slender Delta Wing

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
T. Lee ◽  
L. S. Ko
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Leading Edge ◽  
Ground Effect ◽  
Drag Forces ◽  
Wing Chord ◽  
Ground Distance ◽  
Lift And Drag ◽  
Wing Stall ◽  
Wing In Ground Effect

The ground effect on the aerodynamic loading and leading-edge vortex (LEV) flow generated by a slender delta wing was investigated experimentally. Both the lift and drag forces were found to increase with reducing ground distance (up to 50% of the wing chord). The lift increment was also found to be the greatest at low angles of attack α and decreased rapidly with increasing ground distance and α. The ground effect-caused earlier wing stall was also accompanied by a strengthened LEV with an increased rotational speed and size compared to the baseline wing. The smaller the ground distance, the stronger the LEV and the earlier vortex breakdown became. Meanwhile, the vortex trajectory was also found to be located further inboard and above the delta wing in ground effect compared to its baseline-wing counterpart. Finally, for wing-in-ground effect (WIG) craft with delta-wing planform the most effective in-ground-effect flight should be kept within 10% of the wing chord.

Ground effect on a slender reverse delta wing with anhedral

2018 ◽  
Vol 233 (4) ◽  
pp. 1516-1525
Author(s):  
T Lee ◽  
V Tremblay-Dionne ◽  
LS Ko
Keyword(s):  
Rotational Speed ◽  
Delta Wing ◽  
Ground Effect ◽  
Drag Coefficients ◽  
Drag Forces ◽  
Trailing Edges ◽  
Lift And Drag ◽  
Total Circulation ◽  
Wing In Ground Effect

The ground effect on the lift and drag forces and vortices generated by a slender reverse delta wing with different anhedrals was investigated experimentally. The study was inspired by the Lippisch-type RFB X-114 WIG (wing-in-ground effect) craft for which a reverse delta wing planform with anhedral was employed. The results show that, by positioning the trailing edges of the anhedraled reverse delta wing parallel to the ground, the lift and drag coefficients were found to increase persistently with increasing anhedral as the ground was approached (for ground distances within 40% chord). The observed lift augmentation was also accompanied by an ever-increasing rotational speed and total circulation of the vortices generated by the anhedraled wing. The vortices were also found to be displaced more outboard as the ground was approached, which further suggests their little relevance to the lift generation of the anhedraled reverse delta wing.

scholarly journals Experimental Investigation of a Wing-in-Ground Effect Craft

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Mobassher Tofa ◽  
Adi Maimun ◽  
Yasser M. Ahmed ◽  
Saeed Jamei ◽  
Agoes Priyanto ◽  
...  
Keyword(s):  
Research Work ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Efficiency ◽  
Ground Clearance ◽  
Drag Forces ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Wing In Ground Effect

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

The Influence of Wing Span and Angle of Attack on Racing Car Wing/Wheel Interaction Aerodynamics

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Sammy Diasinos ◽  
Tracie J. Barber ◽  
Graham Doig
Keyword(s):  
Angle Of Attack ◽  
Ground Effect ◽  
Navier Stokes ◽  
Flow Structures ◽  
Wing Span ◽  
Complex Interactions ◽  
Lift And Drag ◽  
Two Bodies ◽  
Wing In Ground Effect

A numerical-based (Reynolds-averaged Navier–Stokes (RANS)) investigation into the role of span and wing angle in determining the performance of an inverted wing in ground effect located forward of a wheel is described, using a generic simplified wheel and NACA 4412 geometry. The complex interactions between the wing and wheel flow structures are investigated to explain either increases or decreases for the downforce and drag produced by the wing and wheel when compared to the equivalent body in isolation. Geometries that allowed the strongest primary wing vortex to pass along the inner face of the wheel resulted in the most significant reductions in lift and drag for the wheel. As a result, the wing span and angle combination that would produce the most downforce, or least drag, in the presence of the wheel does not coincide with what would be assumed if the two bodies were considered only in isolation demonstrating the significance of optimizing these two bodies in unison.

Ground effect on a cropped slender reverse delta wing with anhedral and Gurney flaplike side-edge strips

2018 ◽  
Vol 233 (7) ◽  
pp. 2433-2444 ◽  
Author(s):  
T Lee ◽  
D Huitema ◽  
P Leite
Keyword(s):  
Weight Reduction ◽  
Free Stream ◽  
Delta Wing ◽  
Ground Effect ◽  
Aerodynamic Coefficients ◽  
Side Edge ◽  
A Minor ◽  
Wing In Ground Effect

The ground effect on the aerodynamic coefficients of a cropped slender reverse delta wing equipped with anhedral and Gurney flaplike side-edge strips was investigated experimentally at Re = 3.82 × 105. In a free stream, the 30% cropping was found to cause a minor reduction in lift CL and drag CD coefficients but a promoted stall compared to the noncropped wing. The anhedral caused further CL decrease and CD increase. Meanwhile, the application of side-edge strips produced a significantly increased CL and CD with a minor change to the CL/ CD ratio as compared to the baseline wing. In ground effect, the cropped wing was, however, found to generate more lift compared to the noncropped wing as the ground was approached. The joint anhedral and SES produced a great increment in both CL and CD but a virtually unchanged CL/ CD ratio compared to their outside ground effect counterparts. The larger the side-edge strips’ height the larger the increase in CL. In short, the cropping led to a weight reduction while the addition of anhedral and SES produced a large lift augmentation of the Lippisch-type wing-in-ground effect craft.

Numerical Investigation of the Aerodynamics of a Delta Wing in Ground Effect

2015 ◽  
Vol 52 (1) ◽  
pp. 329-340 ◽  
Author(s):  
Qiulin Qu ◽  
Zhe Lu ◽  
Hao Guo ◽  
Peiqing Liu ◽  
Ramesh K. Agarwal
Keyword(s):  
Numerical Investigation ◽  
Delta Wing ◽  
Ground Effect ◽  
Wing In Ground Effect

Impact of Gurney Flaplike Strips on the Aerodynamic and Vortex Flow Characteristic of a Reverse Delta Wing

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
T. Lee
Keyword(s):  
Vortex Flow ◽  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Force Balance ◽  
Vortex Control ◽  
Lift Curve ◽  
Lift And Drag ◽  
The Impact

The impact of Gurney flaplike strips, of different geometric configurations and heights, on the aerodynamic characteristics and the tip vortices generated by a reverse delta wing (RDW) was investigated via force-balance measurement and particle image velocimetry (PIV). The addition of side-edge strips (SESs) caused a leftward shift of the lift curve, resembling a conventional trailing-edge flap. The large lift increment overwhelmed the corresponding drag increase, thereby leading to an improved lift-to-drag ratio compared to the baseline wing. The lift and drag coefficients were also found to increase with the strip height. The SES-equipped wing also produced a strengthened vortex compared to its baseline wing counterpart. The leading-edge strips (LESs) were, however, found to persistently produce a greatly diffused vortex flow as well as a small-than-baseline-wing lift in the prestall α regime. The downward LES delivered a delayed stall and an increased maximum lift coefficient compared to the baseline wing. The LESs provide a potential wingtip vortex control alternative, while the SESs can enhance the aerodynamic performance of the RDW.

An analysis of aerodynamic forces on a delta wing

1996 ◽  
Vol 316 ◽  
pp. 173-196 ◽  
Author(s):  
Chien-Cheng Chang ◽  
Sheng-Yuan Lei
Keyword(s):  
Mach Number ◽  
Stokes Equations ◽  
Delta Wing ◽  
Leading Edge ◽  
Navier Stokes ◽  
Flow Structures ◽  
Aerodynamic Forces ◽  
Navier Stokes Equations ◽  
Lift And Drag ◽  
Secondary Vortices

The present study aims at relating lift and drag to flow structures around a delta wing of elliptic section. Aerodynamic forces are analysed in terms of fluid elements of non-zero vorticity and density gradient. The flow regime considered is Mα = 0.6 ∼ 1.8 and α = 5° ∼ 19°, where Mα denotes the free-stream Mach number and α the angle of attack. Let ρ denote the density, u velocity, and ω vorticity. It is found that there are two major source elements Re(x) and Ve(x) which contribute about 95% or even more to the aerodynamic forces for all the cases under consideration, \[R_e({\bm x})=-\frac{1}{2} {\bm u}^2 \nabla\rho \cdot \nabla\phi\quad {\rm and}\quad V_e ({\bm x}) = -\rho{\bm u}\times {\bm \omega}\cdot \nabla\phi,\] where θ is an acyclic potential, generated by the delta wing moving with unit velocity in the negative direction of the force (lift or drag). All the physical quantities are non-dimensionalized. Detailed force contributions are analysed in terms of the flow structures and the elements Re(x) and Ve(x). The source elements Re(x) and Ve(x) are concentrated in the following regions: the boundary layer in front of (below) the delta wing, the primary and secondary vortices over the delta wing, and a region of expansion around the leading edge. It is shown that Ve(x) due to vorticity prevails as the source of forces at relatively low Mach number, Mα < 0.7. Above about Mα = 0.75, Re(x) due to compressibility generally becomes the dominating contributor to the lift, while the overall contribution from Ve(x) decreases with increasing Mα, and even becomes negative at Mα = 1.2 for the lift, and at a higher Mα for the drag. The analysis is carried out with the aid of detailed numerical results by solving the Reynolds-averaged Navier–Stokes equations, which are in close agreement with experiments in comparisons of the surface pressure distributions.

Experimental Control of Vortex Breakdown by Pulsed Blowing Over a Delta Wing With Rounded Leading-Edge

2002 ◽  
Author(s):  
Renac Florent ◽  
Molton Pascal ◽  
Barberis Didier
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Laser Sheet ◽  
Leading Edge ◽  
Control Device ◽  
Surface Flow ◽  
Sweep Angle ◽  
Laminar To Turbulent Transition ◽  
Pressure Distributions ◽  
Oil Flow

The purpose of this study is to construct and test an experimental device to control vortex on a delta wing. The model has a root chord of c = 690mm and a sweep angle of Λ = 60°. The control system is based on four rectangular slits 50 mm long and 0.2 mm wide running along the leading edge. This configuration produces jets normal to the leading edge. The mass flow rates and frequencies of injection can be varied independently. The results are shown in the form of surface flow visualizations, with the skin friction pattern exhibited by oil flow visualization, and the laminar-to-turbulent transition by acenaphthene. Mean and instantaneous surface pressure distributions were determined with Kulite™ sensors and the velocity field was determined by 3D laser Doppler velocimetry (LDV) measurements. Control device efficiencies were evaluated by laser sheet visualization.

On the Vortex Breakdown Phenomenon in High Angle of Attack Flows Over Delta Wing Geometries

2014 ◽  
Author(s):  
Eric D. Robertson ◽  
Varun Chitta ◽  
D. Keith Walters ◽  
Shanti Bhushan
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
High Angle ◽  
High Angle Of Attack ◽  
Eddy Simulation ◽  
Wing Model

Using computational methods, an investigation was performed on the physical mechanisms leading to vortex breakdown in high angle of attack flows over delta wing geometries. For this purpose, the Second International Vortex Flow Experiment (VFE-2) 65° sweep delta wing model was studied at a root chord Reynolds number (Recr) of 6 × 106 at various angles of attack. The open-source computational fluid dynamics (CFD) solver OpenFOAM was used in parallel with the commercial CFD solver ANSYS® FLUENT. For breadth, a variety of classic closure models were applied, including unsteady Reynolds-averaged Navier-Stokes (URANS) and detached eddy simulation (DES). Results for all cases are analyzed and flow features are identified and discussed. The results show the inception of a pair of leading edge vortices originating at the apex for all models used, and a region of steady vortical structures downstream in the URANS results. However, DES results show regions of massively separated helical flow which manifests after vortex breakdown. Analysis of turbulence quantities in the breakdown region gives further insight into the mechanisms leading to such phenomena.

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