Search results
1 – 10 of 17Yang Wei and Yang Zhigang
The purpose of this paper is to investigate the aerodynamics of wing in ground effect with tiltable endplates for a new type wing‐in‐ground effect (WIG) craft.
Abstract
Purpose
The purpose of this paper is to investigate the aerodynamics of wing in ground effect with tiltable endplates for a new type wing‐in‐ground effect (WIG) craft.
Design/methodology/approach
The concept of tiltable endplates was implemented into the design of a WIG craft. Numerical investigation on aerodynamics of the tiltable endplate was carried out. The endplate effect on aerodynamics was deeply investigated with a rectangular wing at given angle of attack and flight height. The size of endplate relative to whole wing was then studied based on given endplate deflection angle and flight height. Finally, aerodynamics and flow of tiltable endplate in various flight heights and endplate deflection angles were analyzed. Aerodynamics, pressure and wingtip vortex were recorded in the study.
Findings
Endplate influences development of wingtip vortex and improves aerodynamics. Tiltable endplate can enable WIG craft to yield improved aerodynamic performance and worthwhile economy improvements on long‐distance flights in and out of ground effect (OGE).
Research limitations/implications
The results are entirely based on computational fluid dynamics (CFD). The gap between “numerical world” and “real world” depends on development and appropriate application of CFD. The current work shows further understanding of ground effect and aerodynamics of wing in ground effect.
Practical implications
The aerodynamics and aerodynamic optimization of wing in ground effect are of the great importance for WIG craft. The work improves the design and research on aerodynamics of WIG craft.
Originality/value
The concept of tiltable endplate for a new type wing in ground effect allows WIG craft to achieve good aerodynamic performance not only in ground effect but also in OGE. This was studied and proved in the current work.
Details
Keywords
Mojtaba Tahani, Mehran Masdari and Ali Bargestan
The overall performance of an aerial vehicle strongly depends on the specifics of the propulsion system and its position relative to the other components. The purpose of paper is…
Abstract
Purpose
The overall performance of an aerial vehicle strongly depends on the specifics of the propulsion system and its position relative to the other components. The purpose of paper is this factor can be characterized by changing several contributing parameters, such as distance from the ground, fuselage and wing as well as the nacelle outlet velocity and analyzing the aerodynamic performance.
Design/methodology/approach
Navier–Stokes equations are discretized in space using finite volume method. A KW-SST model is implemented to model the turbulence. The flow is assumed steady, single-phase, viscous, Newtonian and compressible. Accordingly, after validation and verification against experimental and numerical results of DLRF6 configuration, the location of the propulsion system relative to configuration body is examined.
Findings
At the nacelle outlet velocity of V/Vinf = 4, the optimal location identified in this study delivers 16% larger lift to drag ratio compared to the baseline configuration.
Practical implications
Altering the position of the propulsion system along the longitudinal direction does not have a noticeable effect on the vehicle performance.
Originality/value
Aerial vehicles including wing-in-ground effect vehicles require thrust to fly. Generating this necessary thrust for motion and acceleration is thoroughly affected by the vehicle aerodynamics. There is a lack of rigorous understanding of such topics owing to the immaturity of science in this area. Complexity and diversity of performance variables for a numerical solution and finding a logical connection between these parameters are among the related challenges.
Details
Keywords
Mohammad Saeed Seif and Mohammad Tavakoli Dakhrabadi
The purpose of this paper is to present a fast, economical and practical method for mathematical modeling of aerodynamic characteristics of rectangular wing in ground (WIG…
Abstract
Purpose
The purpose of this paper is to present a fast, economical and practical method for mathematical modeling of aerodynamic characteristics of rectangular wing in ground (WIG) effect.
Design/methodology/approach
Reynolds averaged Navier–Stokes (RANS) equations were converted to Bernoulli equation by reasonable assumptions. Also, Helmbold’s equation has been developed for calculation of the slope of wing lift coefficient in ground effect by defining equivalent aspect ratio (ARe). Comparison of present work results against the experimental results has shown good agreement.
Findings
A practical mathematical modeling with lower computational time and higher accuracy was presented for calculating aerodynamic characteristics of rectangular WIG effect. The relative error between the present work results and the experimental results was less than 8 per cent. Also, the accuracy of the proposed method was checked by comparing with the numerical methods. The comparison showed fairly good accuracy.
Research limitations/implications
Aerodynamic surfaces in ground effect were used for reducing wetted surface and increasing speed in high-speed marine and novel aeronautical vehicles.
Practical implications
The proposed method is useful for investigation of aerodynamic performance of WIG vehicles and racing boats with aerodynamic surfaces in ground effect.
Originality/value
The proposed method has reduced the computational time significantly as compared to numerical simulation that allows conceptual design of the WIG crafts and is also economical.
Details
Keywords
Hongwei Ma, Shuai Ren, Junxiang Wang, Hui Ren, Yang Liu and Shusheng Bi
This paper aims to carry out the research on the influence of ground effect on the performance of robotic fish propelled by oscillating paired pectoral fins.
Abstract
Purpose
This paper aims to carry out the research on the influence of ground effect on the performance of robotic fish propelled by oscillating paired pectoral fins.
Design/methodology/approach
The two-dimensional ground effect model of the oscillating pectoral fin without considering flexible deformation is established by introducing a two-dimensional fluid ground effect model. The parameters of the influence of ground effect on the oscillating pectoral fin are analyzed. Finally, the ground effect test platform is built, and a series of hydrodynamic experiments are carried out to study the influence of ground effect on the propulsion performance of the robotic fish propelled by oscillating paired pectoral fins under different motion parameters.
Findings
The thickness of the trailing edge and effective clearance are two important parameters that can change the influence of ground effect on the rigid pectoral fin. The experimental results are consistent with that obtained through theoretical analysis within a certain extent, which indicates that the developed two-dimensional ground effect model in this paper can be used to analyze the influence of ground effect on the propulsion performance of the oscillating pectoral fin. The experiment results show that the average thrust increases with the decreasing distance between the robot fish and the bottom. Meanwhile, with the increase of oscillation frequency and amplitude, the average thrust increases gradually.
Originality/value
The developed two-dimensional ground effect model provides the theoretical basis for the further research on the influence of ground effect on the propulsion performance of the oscillating pectoral fin. It can also be used in the design of the bionic pectoral fins.
Details
Keywords
D.W. Marshall, S.J. Newman and C.B. Williams
The purpose of this paper is to investigate the effect a variety of different boundary layers have on a wing in ground‐effect.
Abstract
Purpose
The purpose of this paper is to investigate the effect a variety of different boundary layers have on a wing in ground‐effect.
Design/methodology/approach
Experiments were carried out in the University of Southampton's 3′×2′ wind tunnel. A variable length splitter plate was designed and manufactured in order to generate four boundary‐layer thicknesses at a selected measurement position. A single element inverted GA(W)‐1 aerofoil was then introduced to the flow at varying heights above the plate. Laser Doppler anemometry (LDA) and surface static pressure measurements (both on the aerofoil surface and on the splitter plate) were recorded.
Findings
The flow beneath the wing is found to be affected considerably by the presence of the boundary layer. As the boundary‐layer thickness is increased, the under‐wing pressure is observed to increase, hence resulting in decreased suction. Further, the LDA results indicate a modification to the wake profile. In particular, at low wing heights, the wake is observed to become entrained in the boundary layer, to differing degrees dependant on the boundary layer present and the wing height.
Research limitations/implications
The acquisition of force values from the tests will have allowed further understanding of the “real world” implications of the presence of the boundary‐layer thicknesses on a wing in ground‐effect but this is not possible in the test facility used.
Practical implications
The aerodynamics of a wing in ground‐effect are of great interest for both lifting surfaces for aircraft and downforce generation in motorsport applications. The implications of this paper enhance the importance of understanding the boundary conditions present when wind tunnel testing for these applications.
Originality/value
Although the influence of the boundary layer on low ground clearance objects has been well documented, the methods used here, in particular the use of the pressure tapped splitter plate and LDA, allow a further insight into the explanations behind this influence.
Details
Keywords
Mojtaba Tahani, Mehran Masdari and Ali Bargestan
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…
Abstract
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.
Details
Keywords
Jafar Masri, Laurent Dala and Benoit Huard
This paper aims to investigate the different analytical methods used to predict the performance of seaplanes to define the weaknesses in each method and be able to extend the…
Abstract
Purpose
This paper aims to investigate the different analytical methods used to predict the performance of seaplanes to define the weaknesses in each method and be able to extend the analytical approach to include the nonlinear terms (unsteadiness).
Design/methodology/approach
First, the elemental hydrodynamic characteristics of seaplanes are discussed. Second, five different analytical methods are reviewed. The advantages and disadvantages of each method are stated. After that, the heave and pitch equations of seaplane motion are illustrated. The procedure of obtaining the solution of the heave and pitch equations of seaplane motion is explained. Finally, the results obtained from the most common methods are compared.
Findings
The results show that the methods are based on different assumptions and considerations. As a result, no method is optimal for all types of seaplanes. Moreover, some of the analytical methods do not study the stability of the seaplane, which is a major issue in the design of seaplanes. In addition, all methods consider the motion as steady and linear. The objective is to extend the work to include the nonlinear effects.
Originality/value
This paper presents some of the analytical methods used in describing the performance of seaplanes and explains how can they be applied. Moreover, it summarises the advantages and disadvantages of each method.
Details
Keywords
Abstract
Purpose of paper
The potential increase in aerodynamic efficiency whilst operating in close proximity to the ground has stimulated substantial interests in the design and applications of Wing‐In‐Ground (WIG) craft. The purpose of this paper is to investigate the aerodynamic and stability characteristics, such as the Aerodynamic Center of Height (ACH) and the Aerodynamic Center of Pitch (ACP) of a NACA4412 airfoil in ground effect and give clear physical and mathematical definitions of ACH and ACP
Design/methodology/approach
Both a panel method and a Finite Volume Method (FVM) have been employed to analyze the aerodynamic and stability characteristics numerically in this paper.
Findings
It is found that for the range of heights and pitch angles investigated, ACH of a NACA 4412 airfoil is only a function of pitch angle while ACP is only a function of height. The ACH of a NACA4412 airfoil lies behind the ACP. When viscous effects are taken into account, the ACH of the NACA4412 airfoil moves further forwards due to boundary layer de‐cambering effects.
Originality/value
These findings are important for preliminary WIG‐craft design and analysis in term of airfoil selection.
Details
Keywords
Jonathan W. Vogt and Tracie J. Barber
Investigations into ground effect phenomena about aerofoils are typically conducted on either an upright (lift‐producing) or inverted (downforce‐producing) configuration, in…
Abstract
Purpose
Investigations into ground effect phenomena about aerofoils are typically conducted on either an upright (lift‐producing) or inverted (downforce‐producing) configuration, in isolation. This limited approach does not promote a holistic understanding of how ground effect influences aerofoils. This paper aims to address this issue.
Design/methodology/approach
A two‐dimensional computational fluid dynamics investigation was conducted on the highly cambered Tyrrell aerofoil, in both its upright and inverted configurations, in order to better understand ground effect phenomena by observing how it influences each configuration differently. The trends in force and flow field behaviour were observed at various ground clearances through observation of the normal and drag forces and pressure coefficient plots. The aerofoil was held stationary and at a constant angle of attack of 6 degrees, with a moving ground plane to simulate the correct relative motion.
Findings
The different ground effect mechanisms that occur on each configuration are highlighted and explained. It is shown how ground effect manifests through these different phenomena and that there are general or overarching mechanisms that influence both configurations. These general mechanisms allow unintuitive phenomena, such as the downward movement of the stagnation point on both configurations, to be explained.
Originality/value
Overarching mechanisms of ground effect are discovered which are of value in any situation in which ground effect aerodynamics is to be exploited.
Details
Keywords
Xiaohui Xiong, Jiaxu Geng, Kaiwen Wang and Xinran Wang
This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method…
Abstract
Purpose
This paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof.
Design/methodology/approach
The improved delayed detached eddy simulation method based on shear stress transport k-
Findings
The wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights.
Originality/value
This paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.
Details