Wing In Ground Effect Research Articles

Very low Reynolds number causes a monotonic force enhancement trend for a three-dimensional hovering wing in ground effect

This research reports the numerical results of the ground effect trend for a three-dimensional flapping insect wing at a very low Reynolds number (Re = 10). It demonstrates that the ground effect trend at this Re has a ‘single force regime,’ i.e. the forces only enhance as the ground distance decreases. This phenomenon is unlike the widely expected non-monotonic trend publicized in previous studies for higher Reynolds numbers, that shows ‘three force regimes,’ i.e. the forces reduce, recover, and also enhance as the ground distance decreases. The force trend in the ground effect correlates to a similar trend in wing–wake interaction or the downwash strength on the wing’s head. At very low Re (10), the very large viscosity causes diffused vortices and less advected vortex wake, while at relatively high Re, the vortices are easily separated from the wing and then advected downwards. This different development of the vortex wake caused different force trends for the flapping wing in the ground effect. Furthermore, by examining only the first stroke when there is no vortex wake, we found that the ‘ramming effect’ enhances the forces on the wing. This effect increases the pressure of the lower wing surface due to the squeezed air between the wing and the ground. The ‘ramming effect’, combined with the reduced downwash (or wing–wake interaction) effect, causes the force enhancement of the wing near the ground’s vicinity. It is further comprehended that the trend is dependent on Re. As the Re is increased, the trend becomes non-monotonic. The effect of varying angles of attack, flapping amplitude and wing planform at very low Re does not change this trend. This ground effect might help insects by enhancing their lift while they hover above the surface. This finding might prove beneficial for developing micro air vehicles.

The Influence of Front Wing Pressure Distribution on Wheel Wake Aerodynamics of a F1 Car

The present study focuses on investigating the aerodynamic interaction between a three-element wing and wheel in ground effect, following the Formula One regulation change set for 2022, among which is the simplification of the front wing. This was accomplished by conducting a three-dimensional computational fluid dynamics analysis, using a Detached-Eddy Simulation approach, on a simplified one-quarter model of a Formula One racing car. The main goal was to examine how changing the front wing pressure distribution, by changing the incidence of the second flap, affected the wheel wake. The flow investigation indicated that the wheel wake is influenced by the flap configuration, which is mainly due to the fact that different flap configurations produce different upwash flow fields, leading to a variation of the separation point on top of the tire. As the separation point moves rearwards, the downwash generated in the central region (for a vertical plane) of the wheel wake increases incrementally, leading to a resultant wake that is shorter and further apart. The force investigation showed that the proximity between the region of instability (i.e., vortex breakdown) and the wing’s trailing edge influences the behavior of the transient oscillations, regarding the forces acting on the wing: detecting higher drag force fluctuations, when compared to downforce fluctuations.

Numerical analysis on the propulsive performance of oscillating wing in ground effect

The transient numerical simulation has been conducted by using of the Overlapping grid technique to investigate the ground wall effect on the propulsive performance of an oscillating wing. Both the two-dimensional and three-dimensional wing have been analyzed and the systematic analysis on the effect of the Reynolds number (Re), the average distance between the flapping foil and ground wall (h0) on the propulsive performance of oscillating wing are investigated with respect to the non-dimensional oscillating frequency (St). The simulation results demonstrate that the existence of the ground wall can produce significant influence on the fluid dynamics of oscillating wing and the ground wall effect has close connection to the magnitude of St number. In addition, the increase of Re number will facilitate the growth of both thrust force and propulsive efficiency of oscillating wing and that influence also has close connection with the St number. Finally, the existence of ground wall can also greatly improve the propulsive performance of three-dimensional oscillating wing, but the sensitivity of three-dimensional oscillating wing to the ground wall is lower than that of two-dimensional oscillating wing. The conclusions acquired here can be utilized to optimize the kinematics of the underwater vehicles swimming near ground wall.

Parameter study on lateral moments of banked wings in ground effect

Ground effect dramatically improves the performance of the Wing-in-Ground (WIG) vehicles near the ground. However, making coordinate turnings in ground effect zone may raise complexity in flight control. The Angle of Attack (AOA) and height are believed to be important factors. To find the impact of these factors, three straight rectangular wings with different aspect ratios are simulated via CFD approach. The results show that in normal situations, the rolling moment tends to level the wing but less effective with the decreasing AOA and changes its direction when the AOA is less than a height dependent value. The yaw moment exhibits complex behavior because two different effects generate oppose moments. The rolling moment coefficient is more influenced by the ground if a wing has larger Aspect Ratio (AR) and works at low to medium AOA. The yawing coefficient is always more influenced if the wing has larger AR regardless AOAs. These findings can provide basic guidance for the design of control system and enable aircraft designers to reshape the crafts to avoid or utilize this effect.

The effect of static deformation on the lift loss phenomenon of an ABS downforce producing wing in ground effect

The proximity of a downforce producing wing to the ground has a significant effect on the generation of aerodynamic loads and flow structures. However, a rigid body assumption for the wing may lead to inaccuracies in the estimation of these loads. Static loosely-coupled Fluid-Structure Interaction (FSI) simulations were performed at Reynolds numbers of 4.64·105 and 6.96·105 and ground clearances ranging from 0.053 c to 0.223 c to investigate the effect of deformation in an ABS wing. Results of these simulations demonstrated that wing deflection increased the height at which lift loss occurred, as the reduced wing tip ground clearance led to an earlier main wing vortex breakdown and greater boundary layer separation. The increase in Reynolds number for a constant chord length induced larger variations in critical height: the critical height increased by 0.011 c at Re = 4.64·105 and by 0.021 c at Re = 6.96·105. The larger variation in critical height at the high Reynolds number cases was due to the increase in the magnitude of the aerodynamic loads, and larger deflections.

Stall in ground effect using the unsteady vortex lattice method with Kirchhoff-based correction

The goal of this research is to evaluate the stall behavior of a high aspect ratio rectangular wing in ground effect using an unsteady vortex-lattice method with a Kirchhoff-based correction (UVLM-K), including how the lift coefficient achieved in stall is affected by dynamic ground effect. A flow separation algorithm based on the Kirchhoff-Helmholtz theory and a flow separation model presented by Fischenberg are applied. The code was validated using experimental data from previously published works. The stall behavior of a rectangular wing of aspect ratio of 8.587 formed with a NACA 4415 airfoil section was studied in static and dynamic ground effect. To obtain the empirical data required by the UVLM-K, the NACA4415 airfoil was simulated at fixed height aboveground using a finite-volume code solver. The wing simulation results have shown that the lift coefficient achieved by the wing in stall for takeoff and flare maneuvers are lower than those estimated at a fixed height above the ground. It can be concluded, based on the results obtained herein, that the stall behavior of a wing in dynamic ground effect depends on the history of the maneuver.

The Effect of Cornering on the Aerodynamics of a Multi-Element Wing in Ground Effect

This research investigates the effects of cornering on a multi-element wing in ground effect with the aim to improve the understanding of such in the effort to improve the performance of open-wheel race cars. A numerical validation study was performed to confirm the validity of the Detached Eddy Simulation CFD methodology used. This involved comparing numerical data with wind tunnel experimental data using a force balance and PIV for the velocity field to reveal the trajectory of the trailing vortex system. Once validated, the CFD was used to test the wing within a cornering condition as well as fixed yaw condition and its aerodynamic performance relative to the straight-line condition was analysed. Asymmetry was the general theme concerning the on-surface pressure distribution with this most prominent under the cornering condition. Ultimately, minimal change was observed regarding the downforce generated whilst drag was found to increase in the cornering condition and decrease slightly in the fixed yaw condition. Asymmetry was also observed in the wake of the wing where alterations to the relative strengths of the vortices was observed as well as their downstream paths which was generally governed by the direction of the freestream flow.

Computational Aerodynamics Analysis of Non-Symmetric Multi-Element Wing in Ground Effect with Humpback Whale Flipper Tubercles

The humpback whale flipper tubercles have been shown to improve the aerodynamic coefficients of a wing, especially in stall conditions, where the flow is almost fully detached. In this work, these tubercles were implemented on a F1 front-wing geometry, very close to a Tyrrell wing. Numerical simulations were carried out employing the k−ω SST turbulence model and the overall effects of the tubercles on the flow behavior were analyzed. The optimal amplitude and number of tubercles was determined in this study for this front wing where an improvement of 22.6% and 9.4% is achieved, respectively, on the lift and the L/D ratio. On the main element, the stall was delayed by 167.7%. On the flap, the flow is either fully detached, in the large circulation zone, or fully attached. Overall, in stall conditions, tubercles improve the downforce generation but at the cost of increased drag. Furthermore, as the tubercles are case-dependent, an optimal configuration for tubercles implementation also exists for any geometry.

The Application of WIG (Wing-In-Ground-Effect) As a More Cost Effective Transportation in the Indonesian Archipelago

Current trends in the design of transport aircraft have shown that in order to be economically viable and competitive it is necessary to investigate technologies that can give an improvement in performance and operational flexibility goal, but must be shown to be cost effective. The current competitive environment forces the potential customers to buy advanced technology aircraft and requires manufacturers to provide more operational flexibility, without drastic performance penalties. This is a challenging task, which might be solved by the use of new technologies. It is believed that the application of a WIG (Wing-in-Ground-Effect) would assist in achieving such a task. This paper describes an investigation aimed to examine the suitability of a WIG concept as a more cost effective transportation in the Indonesian archipelago. This work is unique in terms of application in the Indonesian archipelago. The paper describes the phenomenon of WIG and outlines the benefits and penalties of WIG. It then discusses the possibility of the application of WIG to NKRI. It concludes with a discussion of the results and recommendations for future work.

Analysis of fluid and solid interaction of the flexible bionic wing in ground effect

Animals can obtain excellent locomotion performance as they swim or fly under ground effect in nature. Inspired by this, fluid mechanisms of the flexible bionic wing oscillating and gliding in ground effect are investigated by fluid–solid interaction simulation in this study, respectively. For the oscillation motion, the flexible wing vertically moves up and down at different distances from the ground. Different parameters such as the average height from the ground, oscillation frequency of the flexible bionic wing, and airfoil flexibility are considered in the simulation. At the same time, the gliding motion of the flexible wing in the ground effect is also studied, compared with the oscillation motion. Several simulations are set for different parameters. The characteristics of the force and deformation of the flexible wing and the flow field around the flexible wing are analyzed in depth. The effects of different flexibilities on the force characteristics of oscillation and gliding motion are obtained. The results show that the influence of flexibility on the lift and drag force is different. Optimal motion performance can be achieved within a certain range of flexibility. The ground effect features of the flexible bionic wing with different locomotion modes are acquired.

A Study on the Effect of Debris Location on a Double Element Wing in Ground Effect

<div class="section abstract"><div class="htmlview paragraph">Multi-element front wings are essential in numerous motorsport series, such as Formula 1, for the generation of downforce and control of the onset flows to other surfaces and cooling systems. Rubber tyre debris from the soft compounds used in such series can become attached to the wing, reducing downforce, increasing drag and altering the wake characteristics of the wing. This work studies, through force balance and Particle Image Velocimetry (PIV) measurements, the effect a piece of debris has on an inverted double element wing in ground effect. The debris is modelled using a hard-setting putty and is located at different span and chord-wise positions around the wing. The sensitivity to location is studied and the effect on the wake analysed using PIV measurements. The largest effect on downforce was observed when the debris was located on the underside of the wing towards the endplates. The wake was most effected when the debris was located closest to the gap, generating a large fluctuating wake with a significantly different path to the baseline case.</div></div>

Wake behind a Compound Wing in Ground Effect

Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.

Aerodynamic investigation of blunt and slender bodies in ground effect using OpenFOAM

The main purpose of this numerical study is to assess the capability of OpenFOAM in predicting aerodynamic performance of blunt and slender devices for automotive and motorsport applications such as a diffuser-equipped blunt body and a F1 single element front wing in ground effect. Reynolds Averaged Navier-Stokes (RANS) simulations were carried out at different values of ride height and diffuser angle/angle of attack: predictions of integral quantities, such as drag (CD) and lift (CL) coefficients were validated against the available set of experimental data from Loughborough and Southampton Universities. Results put in evidence that OpenFOAM is suitable for fulfilling the goal of this study, even if the entire workflow (from meshing to calculation) is not user-friendly: the success of the simulations strongly depends on quality of the mesh, turbulence model, type of solver and numerical setup.

Effects of Heaving Motion on the Aerodynamic Performance of a Double-Element Wing in Ground Effect

The broad implication of the paper is to elucidate the significance of the dynamic heaving motion in the aerodynamic performance of multi-element wings, currently considered as a promising aspect for the improvement of the aerodynamic correlation between CFD, wind tunnel and track testing in race car applications. The relationship between the varying aerodynamic forces, the vortex shedding, and the unsteady pressure field of a heaving double-element wing is investigated for a range of mean ride heights, frequencies, and amplitudes, using a two-dimensional (2D) unsteady Reynolds-averaged Navier-Stokes (URANS) approach and an overset mesh method for modelling the moving wing. The analysis of the results shows that at high frequencies, i.e., k ≥ 5:94 and amplitudes a/c ≥ 0:05 the interaction of the shear vorticity between the two elements results in the generation of cohering leading and trailing edge vortices on the flap, associated to the rapid variation of thrust and downforce enhancement. Both the occurrence and intensity of these vortices are dependent upon the frequency, amplitude, and mean ride height of the heaving wing. The addition of the flap significantly alters the frequency of the shed vortices in the wake and maintains the generation of downforce for longer time in ground proximity. The comparison with the static wing provides evidence that the dynamic motion of a race car wing can be beneficial in terms of performance, or detrimental in terms of aerodynamic correlation.

Passive Wingtip Vortex Control by Using Tip-Mounted Half Delta Wings in Ground Effect

Abstract The ground effect on the wingtip vortex generated by a rectangular semiwing equipped with tip-mounted regular and reverse half delta wings was investigated experimentally. The passive tip vortex control always led to a reduced lift-induced drag as the ground was approached. In close ground proximity, the presence of the corotating ground vortex (GV) added vorticity to the tip vortex while the counter-rotating secondary vortex (SV) negated its vorticity level. The interaction of the GV and SV with the tip vortex and their impact on the lift-induced drag were discussed. Physical mechanisms responsible for the change in the vortex flow properties in ground effect were also provided.

Experimental Investigation of Seabird-Like Wings in Ground Effect

Seabirds are birds that are adapted to life within the marine environment. They usually fly over and close to the surface of the sea during hunting for food. It is believed that the shapes of their wing structures may have advantages in flying proximity to the surface of the sea better than other birds. It is expected that the study of the characteristics of these wing shapes is useful to the wing in ground effect (WIG) design. Hence, this research aims to investigate the aerodynamic characteristics of various seabird-like wings in proximity of the ground. The wings with and without ground effect are aerodynamically tested in a close circuit low speed wind tunnel of 1 m. × 1 m. test section and at free stream velocity of 40 m/s or Reynolds Number of 240,000. The test results show the effect of ground proximity to the aerodynamic performance of the wings, such as the lift coefficients, the drag coefficients, and the lift to drag ratio, at variety of angles of attack. The stall characteristics are also investigated. The aerodynamic performances of the seabird-like wings are also compared to the rectangular wing of the same aspect ratio. It is concluded that the wings of seabird like shapes provide better aerodynamic performance when in ground effect compared to the normal rectangular wing.

Towards the modeling of the ditching of a ground-effect wing ship within the framework of the SPH method

Ditching often takes place for a ground-effect wing (WIG) ship. During the ditching, the extreme load developed by water impacts may cause damages to structures, posing a great threat to the safety of crew and passengers. In the paper, a weakly compressible smoothed particle hydrodynamics (SPH) model combined with enhanced numerical techniques has been adopted to tackle the ditching problems. In order to handle the motion of a rigid body in the three-dimensional ditching problems, the six degrees-of-freedom (6-DOF) equations of motion are incorporated into the SPH scheme. The accuracy of the SPH model is validated through two benchmarks, respectively, the two-dimensional wedge water entry and the three-dimensional stone-skipping. The former is aimed to validate the prediction of pressures during the free surface impact while the latter is a good case for testing the coupling motions of the rigid body. Furthermore, the ditching of the real scale WIG ship under different conditions is simulated with the established SPH model, through which some useful conclusions are drawn.

Flight in Ground Effect Dramatically Reduces Aerodynamic Costs in Bats

Most flying animals, from insects to seabirds [1], perform flights close to ground or water when taking off or landing [2], drinking, and feeding [3-5] or when traveling near water surfaces [1, 6, 7]. When flying close to a surface within approximately one wingspan, the surface acts as an aerodynamic mirror, interrupting the downwash [8, 9], resulting in increased pressure underneath the wing and suppression of wingtip vortex development [10]. This aerodynamic interaction lowers the energy added to the air by the animal, reducing the cost of flying. Modeling suggests that flapping wings in ground effect can affect the expected power savings compared to gliding flight, either positively or negatively, depending on the wing motion [11-13]. Although aerodynamic theory predicts substantial power reductions when animals fly in ground effect [4-6, 9, 11, 12], quantitative measurements of savings are lacking. Here, we show, through wake-based power measurements, that Daubenton's bats utilize 29% less aerodynamic power when flying in compared to out of ground effect, which is twice the predicted savings. Contrary to theoretical predictions [4-6, 9, 11, 12] we find no variation in savings with distance above ground when in ground effect. Given alterations in kinematics withground proximity, we hypothesize that modulation of wing kinematics raises the achievable benefit from ground effect relative to current model predictions. The savings from ground effect are comparable to formation flight [14, 15] but are not limited to large bird species. Instead, ground effect is experienced by most flying animals and may have facilitated the evolution of powered animal flight.

Wing-in-ground-effect craft: A case study in aerodynamics

A wing-in-ground-effect (WIGE) crafts can be deployed to fly by utilizing the ground effect, which is a natural phenomenon known to improve the efficiency of airplanes during take-off and landing approaches. In contrast, WIGE craft is not commercially viable for public transport mainly due to the difficulties in controlling its longitudinal stability. As an attempt to support the development of WIGE crafts, this paper presents a case study in aerodynamics based on certain published reports, specifically to reveal the available research data that are considered of interest and can be used as a lesson for further study and analysis. The wind tunnel procedure and testing, as well as numerical investigation of a WIGE craft, are applied and the results are then analyzed. The discussions are oriented in the perspectives of aerodynamics. Based on the tests and calculation, parameters concerning the ground effect as the WIGE crafts approaching the ground surfaces may be identified and hence their values can be determined. Thus, the static longitudinal stability may then be established and optimized for control of the WIGE craft.

Aerodynamics of a Transonic Airfoil in Ground Effect

The wing-in-ground-effect (WIG) aircraft operates with larger lift-to-drag ratio compared to a conventional aircraft at low subsonic Mach numbers. To increase traffic volume of WIG aircraft, one possible way is to increase flight speed, which can result in transonic flow. Currently studies on transonic flight in ground effect are few. The goal of this paper is to study aerodynamics and flow physics of typical transonic RAE2822 airfoil at angles of attack from 0 to 12 deg and Mach numbers from 0.5 to 0.8 in ground effect by varying the ground clearance. The compressible Reynolds-averaged Navier–Stokes equations with Spalart–Allmaras turbulence model are solved using FLUENT. For flight near the ground, some interesting shock formations are obtained due to transonic flow. For unsteady shock buffet on the upper surface, the buffet boundary in angle of attack (AOA)–Mach number plane shrinks with the decreasing ground clearance. Compared to the unbounded flowfield, there exists a steady shock on the lower surface of the airfoil in ground effect for low AOAs because the channel between the lower surface of the supercritical airfoil and the ground is of typical converging–diverging shape, resulting in decrease in lift and increase in drag.