Experimental investigation of the aerodynamic characteristics of generic fan-in-wing configurations

2009 ◽  
Vol 113 (1139) ◽  
pp. 9-20 ◽  
Author(s):  
N. Thouault ◽  
C. Breitsamter ◽  
N. A. Adams ◽  
C. Gologan ◽  
J. Seifert
Keyword(s):  
Experimental Investigation ◽  
Lift Coefficient ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Flow Visualisation ◽  
Force Measurements ◽  
Tunnel Model ◽  
Image Velocimetry ◽  
Flow Circulation ◽  
Stereo Particle Image Velocimetry

Abstract This experimental investigation concentrates on the aerodynamic behaviour of a generic fan-in-wing configuration. The effects of the fan(s) on the flow circulation in a short take-off and landing or a transition flight condition without ground effect are evaluated. A wind-tunnel model has been constructed and tested to quantify the aerodynamic effects. Force measurements, surface pressure measurements, stereo-particle image velocimetry and wool tufts flow visualisation are performed. Different fan-in-wing configurations with the fans rotating in the wing plane, one fan either at the rear or front part of the wing and two fans are compared to the closed wing without fans set as reference. A fan placed near the trailing edge improves significantly the lift coefficient due to a jet flap effect on the wing lower side combined with enhanced suction on the wing upper side. The jet exiting the nozzle rolls up in a counter rotating pair of vortices affecting significantly the wing behaviour. This experimental investigation constitutes also a useful database for further CFD comparison.

scholarly journals Experimental Investigation of the Ground Effect of WIG Craft—NEW1 Model

Proceedings ◽  
2020 ◽  
Vol 39 (1) ◽  
pp. 17
Author(s):  
Sakornsin ◽  
Thipyopas ◽  
Atipan
Keyword(s):  
Lift Coefficient ◽  
Ground Surface ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Scale Model ◽  
Negative Slope ◽  
Stream Velocity ◽  
Longitudinal Stability ◽  
Moment Coefficient ◽  
The Moment

Navy Experimental Wing-in-Ground-Effect (WIG) craft namely as NEW1, is the first version of 2-seated WIG craft which has been designed and developed by Royal Thai Navy since 2017. This experimental research is a part of the NEW1 project which aims to investigate the aerodynamic characteristics and aspects of the flow passing through the WIG craft model when in ground effect. In the experiment, the WIG craft—NEW1 of 1:15 scale model is tested in a close circuit wind tunnel of 1 m × 1 m test section at Kasetsart University. The tests are conducted at the free stream velocity of 40 m/s or Reynolds number of 280,000, at angles of attack ranging from −9° to 21°, and at the wing to ground distances ranging from 5.0 C to 0.3 C. The measurement of 6-DoF of forces and moments and pressure distributions on the ground surface underneath the WIG craft model are made during the tests. The results show that the ground has significant effects on the aerodynamic characteristics of the WIG craft model when the wing to ground distance is less than its mean chord. It was found that when the model move from 5.0 C (out of ground effect) to 0.3 C, the lift coefficient increases up to 15.7%, the drag coefficient decreases up to 5.6%, and the lift to drag ratio increases 33.4%. The proximity of the model to the ground also affects the longitudinal stability of the model. The moment coefficient curves against angle of attack has negative slope for both in and out of ground effect indicating favorable longitudinal stability. However, it was found that the aerodynamic center move further aft toward the trailing edge when the model move closer to the ground.

An Historical and Applied Aerodynamic Study of the Wright Brothers’ Wind Tunnel Test Program and Application to Successful Manned Flight

2005 ◽  
Author(s):  
Michael G. Dodson ◽  
David S. Miklosovic
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Scaling Effects ◽  
Force Measurements ◽  
Velocity Gradients ◽  
Tunnel Model ◽  
Image Velocimetry ◽  
Manned Flight ◽  
Flow Quality ◽  
Scale Design

A replica wind tunnel was built and used to test the flow quality through the Wright Brothers’ wind tunnel. The research determined the effect flow quality and experimental method had on the Brothers’ results, and whether those results were useful in a quantitative sense. Particle image velocimetry revealed boundary layers extending 2.5” (63.5 mm) from each wall, and velocity gradients as large as 20% along the wind tunnel model span resulting in an asymmetric lift distribution. Similarly, the balance generated asymmetric wingtip vortices contributing to asymmetric downwash along the span of the model. Direct force measurements of a replica of the Wrights #12 airfoil showed their lift measurements were at least 7% and as much as 15% too low, and numerical analysis revealed wind tunnel predictions for lift, drag, and efficiency were not applicable to full scale design due to Reynolds number scaling effects.

Flow visualisation of the helicopter brown-out phenomenon

2009 ◽  
Vol 113 (1145) ◽  
pp. 467-478 ◽  
Author(s):  
N. D. Nathan ◽  
R. B. Green
Keyword(s):  
Particle Image ◽  
Dust Cloud ◽  
Ground Effect ◽  
Flow Visualisation ◽  
Forward Speed ◽  
Fine Dust ◽  
Dust Clouds ◽  
Image Velocimetry ◽  
Series Of Experiments ◽  
The Mean

Abstract Quantitative and qualitative results of a series of experiments conducted on a rotor in ground effect at low forward speeds are presented. The velocity over a wide area of the ground effect wake was measured using particle image velocimetry, and the evolution of the flow is described as the forward speed increases. The formation of a dust cloud leading to so-called helicopter brown-out was simulated through a series of flow visualisation experiments. The technique involved sprinkling a fine dust on the ground below and ahead of the rotor. Larger dust clouds were observed at lower forward speed, and the dust cloud penetrated into the areas of the flow including those where vorticity levels were of low magnitude and occasional velocity fluctuations from the mean were large.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Experimental study of flow around polygonal cylinders

2016 ◽  
Vol 812 ◽  
pp. 251-278 ◽  
Author(s):  
S. J. Xu ◽  
W. G. Zhang ◽  
L. Gan ◽  
M. G. Li ◽  
Y. Zhou
Keyword(s):  
Reynolds Number ◽  
Lift Coefficient ◽  
Separation Point ◽  
Flow Visualisation ◽  
Outer Diameter ◽  
Roughness Elements ◽  
Image Velocimetry ◽  
Inner Diameter ◽  
The Difference ◽  
The Relationship

The wake of polygonal cylinders with side number $N=2\sim \infty$ is systematically studied based on fluid force, hot-wire, particle image velocimetry and flow visualisation measurements. Each cylinder is examined for two orientations, with a flat surface or a corner leading and facing normally to the free stream. The Reynolds number $Re$ is $1.0\times 10^{4}\sim 1.0\times 10^{5}$, based on the longitudinally projected cylinder width. The time-averaged drag coefficient $C_{D}$ and fluctuating lift coefficient on these cylinders are documented, along with the characteristic properties including the Strouhal number $St$, flow separation point and angle $\unicode[STIX]{x1D703}_{s}$, wake width and critical Reynolds number $Re_{c}$ at which the transition from laminar to turbulent flow occurs. It is found that once $N$ exceeds 12, $Re_{c}$ depends on the difference between the inner diameter (tangent to the faces) and the outer diameter (connecting corners) of a polygon, the relationship being approximately given by the dependence of $Re_{c}$ on the height of the roughness elements for a circular cylinder. It is further found that $C_{D}$ versus $\unicode[STIX]{x1D709}$ or $St$ versus $\unicode[STIX]{x1D709}$ for all the tested cases collapse onto a single curve, where the angle $\unicode[STIX]{x1D709}$ is the corrected $\unicode[STIX]{x1D703}_{s}$ associated with the laterally widest point of the polygon and the separation point. Finally, the empirical correlation between $C_{D}$ and $St$ is discussed.

scholarly journals Numerical and experimental investigation of the flow separation over NREL's S822 aerofoil and its control by suction and blowing

2021 ◽  
Vol 6 ◽  
pp. 5
Author(s):  
Nazar Aldabash‎‎ ◽  
Andrew Wandel‎ ◽  
Abdul Salam Darwish‎ ◽  
Jayantha Epaarachchi‎
Keyword(s):  
Experimental Investigation ◽  
Wind Turbine ◽  
Flow Separation ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Volumetric Flow Rate ◽  
Aerodynamic Characteristics ◽  
Careful Selection ◽  
Suction And Blowing

In this study, a numerical and experimental investigation for the flow separation over 170 mm chord, the NREL S822 aerofoil low Reynolds number wind turbine blade aerofoil section has been investigated at 15.8 m/s wind speed using suction and blowing techniques for the locations between 0.15 and 0.41 of the chord to improve aerodynamic characteristics of a wind turbine rotor blade. In a numerical study, two-dimensional aerofoil (i.e. NREL S822), using Shear Stress Transport (SST (γ − Reθ)) turbulence model, is presented. Careful selection for the number of mesh was considered through an iterative process to achieve the optimum mesh number resulted in optimum values for the ratio of lift to drag coefficients (CL/CD). Values of the lift coefficient, drag coefficient, and separation location were investigated at an angle of attack 18°. Flow separation is monitored and predicted within the numerical results at the tested angles, which has been compared with the experimental results and should a fair agreement. The results revealed that the aerodynamic characteristics of NERL S822 aerofoil would be improved using the suction technique more than the suction and blowing techniques and there is a delay of flow separation with the increase of blowing or suction volumetric flow rate. Using these two techniques and careful selection of the mesh numbers with the right angle of attack can improve the aerofoil characteristics and therefore lead to improve the turbine performance characteristics.

Experimental Investigation of the Aerodynamics and Flowfield of a NACA 0015 Airfoil Over a Wavy Ground

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
T. Lee ◽  
V. Tremblay-Dionne
Keyword(s):  
Lift Coefficient ◽  
Ground Effect ◽  
Lower Surface ◽  
Moment Coefficient ◽  
Aerodynamic Properties ◽  
Image Velocimetry ◽  
Ground Distance ◽  
Almost All ◽  
Naca 0015 ◽  
The Impact

The aerodynamic properties and flowfield of a NACA 0015 airfoil over a wavy ground were investigated experimentally via surface pressure and particle image velocimetry (PIV) measurements. Flat-surface results were also obtained to be served as a comparison. For the wavy ground, there exhibited a cyclic variation in the sectional lift coefficient Cl over an entire wavelength. The maximum Cl observed at the wave peak (produced by the wavy ground-induced RAM pressure) and minimum Cl occurred at the wave valley (resulting from the unusual suction pressure developed on the airfoil's lower surface due to the converging-diverging flow passage developed underneath it) reduced with increasing ground distance. By contrast, the pitching-moment coefficient showed an opposite trend to the variation in Cl and had an almost all-negative value. Meanwhile, two peak values in the drag coefficient over each wavelength were observed. The wavy ground effect-produced gains in the mean Cl and lift-to-drag ratio were at the expense of longitudinal stability. Additional measurements considering different wavelengths and amplitudes are needed to further quantify the impact of wavy ground on wing-in-ground effect (WIG) airfoils and wings.

Numerical Simulation on Aerodynamic of the Wing in Ground Effect

2012 ◽  
Vol 546-547 ◽  
pp. 200-205
Author(s):  
Rong Wu ◽  
Feng Liang
Keyword(s):  
Numerical Simulation ◽  
Drag Coefficient ◽  
Finite Volume Method ◽  
Lift Coefficient ◽  
Ground Effect ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performances ◽  
Volume Method ◽  
Drag Ratio

Aerodynamic characteristics of the wing NACA5312 in ground effect are investigated with the numerical simulation method. The N-S equations and the k-ε turbulence model are solved by the finite volume method in CFD software. This paper computes the flying states under different clearances, steam velocities and angles of attack. Compared with results under the unbounded flow, it studies the relations between the aerodynamic performances and the angles of attack, the steam velocity, and the relative heights. The aerodynamic performances include the lift coefficient, drag coefficient, and lift-drag ratio.

Aerodynamic performance improvement of WIG aircraft

2017 ◽  
Vol 89 (1) ◽  
pp. 120-132 ◽  
Author(s):  
Mojtaba Tahani ◽  
Mehran Masdari ◽  
Ali Bargestan
Keyword(s):  
Dihedral Angle ◽  
Twist Angle ◽  
Lift Coefficient ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Sweep Angle ◽  
Content Type ◽  
Ground Clearance ◽  
Geometrical Characteristics

Purpose This paper aims to investigate the aerodynamic characteristics as well as static stability of wing-in-ground effect aircraft. The effect of geometrical characteristics, namely, twist angle, dihedral angle, sweep angle and taper ratio are examined. Design/methodology/approach A three-dimensional computational fluid dynamic code is developed to investigate the aerodynamic characteristics of the effect. The turbulent model is utilized for characterization of flow over wing surface. Findings The numerical results show that the maximum change of the drag coefficient depends on the angle of attack, twist angle and ground clearance, in a decreasing order. Also, it is found that the lift coefficient increases as the ground clearance, twist angle and dihedral angle decrease. On the other hand, the sweep angle does not have a significant effect on the lift coefficient for the considered wing section and Reynolds number. Also, as the aerodynamic characteristics increase, the taper ratio befits in trailing state. Practical implications To design an aircraft, the effect of each design parameter needs to be estimated. For this purpose, the sensitivity analysis is used. In this paper, the influence of all parameter against each other including ground clearance, angle of attack, twist angle, dihedral angle and sweep angle for the NACA 6409 are investigated. Originality/value As a summary, the contribution of this paper is to predict the aerodynamic performance for the cruise condition. In this study, the sensitivity of the design parameter on aerodynamic performance can be estimated and the effect of geometrical characteristics has been investigated in detail. Also, the best lift to drag coefficient for the NACA 6409 wing section specifies and two types of taper ratios in ground effect are compared.

Sign in / Sign up

Export Citation Format

Share Document