Research on Hydrodynamic Performance of Three-Dimensional Airfoil with Tubercles on Leading-Edge

2014 ◽  
Vol 575 ◽  
pp. 405-413 ◽  
Author(s):  
Xin Chang ◽  
Xin Ning Wang ◽  
Xiang Ru Cheng
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Attack Angle ◽  
Hydrodynamic Performance ◽  
Vital Importance ◽  
Fluent Software ◽  
Stall Angle ◽  
Save Energy ◽  
And Control ◽  
Drag Ratio

This paper aims to improve and control hydrodynamic performance of three-dimensional airfoils and investigate hydrodynamic performance of three-dimensional airfoil with tubercles on leading-edge by imitating the sinusoidal leading-edge systematically. Based on the DES method, a series of parameters, such as amplitudes and numbers of tubercles, had been studied via the FLUENT software with model constructed by ICEM software and divided by structural grid. According to the results, the amplitudes significantly affect the hydrodynamic performance of three-dimensional airfoil. With maintaining other conditions,tubercle airfoils can make stall angle delay, raise the lift and the drag ratio coefficient. Especially, if there is a bigger attack angle, it is better to reduce resistance and save energy, which will be a cornerstone for further study. It is of vital importance to find out appropriate amplitudes and numbers of tubercles to achieve further progress in hydrodynamic performance of three-dimensional airfoil.

Paper 20. Improvement of Control by Special Devices

1972 ◽  
Vol 14 (7) ◽  
pp. 150-154
Author(s):  
H. Ritter
Keyword(s):  
Large Angle ◽  
Leading Edge ◽  
Rotating Cylinder ◽  
Practical Significance ◽  
Trailing Edge ◽  
Stall Angle ◽  
Lift Control ◽  
And Control

The paper discusses hydrodynamic devices for improving manoeuvring and control. Two hydrodynamic concepts are shown to be of practical significance for large craft: control of hydrofoil lift independent of incidence, and deflection of the propulsion jet through a large angle by means of a simple hydrofoil. Lift control independent of incidence is illustrated by the jet flap and the trailing edge rotating cylinder. Improved deflection of the propeller slipstream involves extending the rudder stall angle, and it is shown how this may be achieved by fitting the rudder with a leading edge rotating cylinder.

The effect of leading-edge droop on the performance of cavitating hydrofoil in an oscillating environment

2009 ◽  
Vol 223 (10) ◽  
pp. 2331-2339
Author(s):  
K Park ◽  
H Sun ◽  
S Lee
Keyword(s):  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Control Surface ◽  
Navier Stokes ◽  
Two Phase ◽  
Sheet Cavitation ◽  
Maximum Angle ◽  
Oscillating Motion ◽  
Drag Ratio ◽  
Cavitating Hydrofoil

The hydrodynamics of cavitating hydrofoil in oscillating motion are important in the aspect of the performance and hydro-elasticity of the control surface of the ship. The effect of leading-edge droop is numerically studied in the oscillating hydrofoil with cavitation. A two-phase incompressible Navier—Stokes solver is used to compute the cavitation flow. The hydrodynamic performance of the baseline hydrofoil is compared with that of the fixed droop and the variable droop hydrofoil. The droop models delay the separation behind the sheet cavitation near the maximum angle of attack. When the pitch goes down, the drooped models suppress the collapse of the sheet cavitation. Therefore, they result in the improved hydrodynamic performance against the baseline model through the oscillation cycle. Among the three hydrofoils, the variable droop showed the smallest change of the lift-to-drag ratio.

Effects of leading-edge bevel angle on the aerodynamic forces of a non-slender 50° delta wing

2005 ◽  
Vol 109 (1098) ◽  
pp. 403-407 ◽  
Author(s):  
J. J. Wang ◽  
S. F. Lu
Keyword(s):  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Relative Thickness ◽  
Aerodynamic Performances ◽  
Stall Angle ◽  
Drag Ratio ◽  
Low Speed Wind Tunnel ◽  
Lift To Drag Ratio ◽  
Blunt Leading Edge

Abstract The aerodynamic performances of a non-slender 50° delta wing with various leading-edge bevels were measured in a low speed wind tunnel. It is found that the delta wing with leading-edge bevelled leeward can improve the maximum lift coefficient and maximum lift to drag ratio, and the stall angle of the wing is also delayed. In comparison with the blunt leading-edge wing, the increment of maximum lift to drag ratio is 200%, 98% and 100% for the wings with relative thickness t/c = 2%, t/c = 6.7% and t/c = 10%, respectively.

Numerical Investigation of Bionic Rudder With Leading-Edge Protuberances

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Hongtao Gao ◽  
Wencai Zhu
Keyword(s):  
Electron Microscopy ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Spanwise Direction ◽  
Flow Mechanism ◽  
Suction Surface ◽  
Edge Profile ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The duck's webbed feet are observed by using electron microscopy, and observations indicate that the edges of the webbed feet are the shape of protuberances. Therefore, the rudder with leading-edge protuberances is numerically studied in the present investigation. The rudder has a sinusoidal leading-edge profile along the spanwise direction. The hydrodynamic performance of rudder is analyzed under the influence of leading-edge protuberances. The present investigations are carried out at Re = 3.2 × 105 and 8 × 105. In the case of Re = 3.2 × 105, the curves of lift coefficient illustrate that the protuberant leading-edge scarcely affects the lift coefficient of bionic rudder. However, the drag coefficient of the bionic rudder is markedly lower than that of the unmodified rudder. Therefore, the lift-to-drag ratio of the bionic rudder is obviously higher than the unmodified rudder. In another case of Re = 8 × 105, the advantageous behavior of the bionic rudder with leading-edge protuberances is mainly performed in the post-stall regime. The flow mechanism of the significantly increased efficiency by the protuberant leading-edge is explored. It is obvious that the pairs of counter-rotating vortices are presented over the suction surface of bionic rudder, and therefore, the flow is more likely to adhere to the suction surface of bionic rudder.

Hydrodynamics and Flow Characterization of Tuna-Inspired Propulsion in Forward Swimming

2019 ◽  
Author(s):  
Junshi Wang ◽  
Huy Tran ◽  
Martha Christino ◽  
Carl White ◽  
Joseph Zhu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Underwater Vehicle ◽  
Numerical Approach ◽  
Primary Objective ◽  
Computational Effort ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Immersed Boundary ◽  
Ring Structures

Abstract A combined experimental and numerical approach is employed to study the hydrodynamic performance and characterize the flow features of thunniform swimming by using a tuna-inspired underwater vehicle in forward swimming. The three-dimensional, time-dependent kinematics of the body-fin system of the underwater vehicle is obtained via a stereo-videographic technique. A high-fidelity computational model is then directly reconstructed based on the experimental data. A sharp-interface immersed-boundary-method (IBM) based incompressible flow solver is employed to compute the flow. The primary objective of the computational effort is to quantify the thrust performance of the model. The body kinematics and hydrodynamic performances are quantified and the dynamics of the vortex wake are analyzed. Results have shown significant leading-edge vortex at the caudal fin and unique vortex ring structures in the wake. The results from this work help to bring insight into understanding the thrust producing mechanism of thunniform swimming and to provide potential suggestions in improving the hydrodynamic performance of swimming underwater vehicles.

A simple vortex-loop-based model for unsteady rotating wings

2019 ◽  
Vol 880 ◽  
pp. 1020-1035 ◽  
Author(s):  
Juhi Chowdhury ◽  
Matthew J. Ringuette
Keyword(s):  
Lift Force ◽  
Current Model ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Vortex ◽  
Vortex Loop ◽  
Edge Vortex ◽  
Semi Empirical ◽  
And Control ◽  
Angular Impulse

An analytical model is developed for the lift force produced by unsteady rotating wings; this configuration is a simple representation of a flapping wing. Modelling this is important for the aerodynamic and control-system design for bio-inspired drones. Such efforts have often been limited to being two-dimensional, semi-empirical, sometimes computationally expensive, or quasi-steady. The current model is unsteady and three-dimensional, yet simple to implement, requiring knowledge of only the wing kinematics and geometry. Rotating wings produce a vortex loop consisting of the root vortex, leading-edge vortex, tip vortex and trailing-edge vortex, which grows with time. This is modelled as a tilted planar loop, geometrically specified by the wing size, orientation and motion. By equating the angular impulse of the vortex loop to that of the fluid volume driven by the wing, the circulatory lift force is derived. Potential flow theory gives the fluid-inertial lift. Adding these two contributions yields the total lift formula. The model shows good agreement with a range of experimental and computational cases. Also, a steady-state lift model is developed that compares well with previous work for various angles of attack.

scholarly journals Flow interaction of three-dimensional self-propelled flexible plates in tandem

2021 ◽  
Vol 931 ◽  
Author(s):  
G. Arranz ◽  
O. Flores ◽  
M. García-Villalba
Keyword(s):  
Three Dimensional ◽  
Vertical Motion ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Vortex Rings ◽  
Stable Configuration ◽  
Horizontal Distance ◽  
Flexible Plates ◽  
Higher Power ◽  
Semi Empirical

Tandem configurations of two self-propelled flexible flappers of finite span are explored by means of numerical simulations. The same sinusoidal vertical motion is imposed on the leading edge of both flappers, but with a phase shift ( $\phi$ ). In addition, a vertical offset, $H$ , is prescribed between the flappers. The configurations that emerge are characterized in terms of their hydrodynamic performance and topology. The flappers reach a stable configuration with a constant mean propulsive speed and a mean equilibrium horizontal distance. Depending on $H$ and $\phi$ , two different tandem configurations are observed, namely compact and regular configurations. The performance of the upstream flapper (i.e. the leader) is virtually equal to the performance of an isolated flapper, except in the compact configuration, where the close interaction with the downstream flapper (i.e. the follower) results in higher power requirements and propulsive speed than an isolated flapper. Conversely, the follower's performance is significantly affected by the wake of the leader in both regular and compact configurations. The analysis of the flow shows that the follower's performance is influenced by the interaction with the vertical jet induced by the vortex rings shed by the leader. This interaction can be beneficial or detrimental for the follower's performance, depending on the alignment of the jet velocity with the follower's vertical motion. Finally, a qualitative prediction of the performance of a hypothetical follower is presented. The model is semi-empirical, and it uses the flow field of an isolated flapper.

scholarly journals Hydrodynamics Around a Deep-Draft Semi-Submersible With Biomimetic Tubercle Corner Design

2019 ◽  
Author(s):  
Yibo Liang ◽  
Weichao Shi ◽  
Longbin Tao
Keyword(s):  
Shear Layer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Shape Design ◽  
Fluid Physics ◽  
Motion Responses ◽  
Shape Effects ◽  
Spanwise Flow

Abstract Leading-edge tubercles have been investigating widely on the performance of foils in the last decade. In this study, the biomimetic tubercle design has been applied to the corner shape on a deep-draft semi-submersible. A numerical study on flow over a deep-draft semi-submersible (DDS) with a biomimetic tubercle corner shape was carried out to investigate the corner shape effects on the overall hydrodynamics and motion responses. The hydrodynamic performance of the biomimetic tubercle corner is compared with a traditional round corner design platform. It is demonstrated that, as the corner shape design changed, the motion responses alter drastically. In addition, the flow patterns were examined to reveal some insights into fluid physics due to the biomimetic tubercle corner design. The comprehensive numerical results showed that the three-dimensional effect, which causes spanwise flow, can be reduced by a continuous spanwise (column-wise) variation of the shear-layer separation points.

3-D Dynamic Simulation of the High-Speed Measurement Turbine under Cavitation

2014 ◽  
Vol 644-650 ◽  
pp. 849-852
Author(s):  
Yong Chen ◽  
He Zhang ◽  
Shao Jie Ma
Keyword(s):  
Dynamic Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Attack Angle ◽  
Dynamics Simulation ◽  
Secondary Development ◽  
Complex Flow ◽  
Speed Measurement ◽  
Movement Characteristics ◽  
Fluent Software

The external turbine can be used on underwater high-speed moving body to measure its own velocity. By establishing the rotating turbine dynamic equations and using UDF programming for secondary development on fluent software, the three-dimensional dynamic simulation of water speed measurement turbine model was achieved. Using this model, under the complex flow environment like cavitation and small attack angle, the dynamics simulation was performed and the results was analyzed to get the turbine movement characteristics. Simulation results show that the simulation model can reflect the variation in characteristics of the turbine caused by the small attack angle at cavitation situation.

Vortex development on pitching plates with lunate and truncate planforms

2013 ◽  
Vol 732 ◽  
pp. 332-344 ◽  
Author(s):  
Colin Hartloper ◽  
David E. Rival
Keyword(s):  
Vortex Formation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Strongly Correlated ◽  
Near Wake ◽  
Relaxation Phase ◽  
Force Relaxation ◽  
Edge Vortex ◽  
Drag Ratio ◽  
Lift To Drag Ratio

AbstractThe three-dimensional flow field and instantaneous forces are measured on pitching rectangular, lunate and truncate planforms of aspect-ratio four. The leading-edge vortex on the rectangular planform is compressed as it grows, and subsequently forms an arch-shaped vortex. For the lunate and truncate planforms, which both have identical spanwise leading-edge curvature but differ in planform area, outboard-directed convection of vorticity, rather than vortex stretching, mitigates arch-vortex formation. The vortical near wake that is formed by the planforms with spanwise leading-edge curvature is found to be strongly correlated with a favourable lift-to-drag ratio during the force-relaxation phase.

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