Aerodynamic effects of corrugation configurations in sweeping- pitching flight

Some insects possess corrugated wings, which distinguish from the ordinary airfoils. It is important to research the corrugation effect on the aerodynamic performances. A series of corrugated wing models were designed based on former research in represent study to find out the underlying mechanisms. The effects of the corrugation pattern and inclination angle were studied using computational fluid dynamic (CFD) method during hovering flight at Reynolds numbers in the order of 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided. The findings are as follows: (1) the results of this paper show that patterns of corrugation have different effect on aerodynamic performances. The corrugated wing like Corrug-1 changes the lift and drag very slightly compared with a flat-plate. The corrugation patterns like Corrug-2 and 3 of wing model reduce the lift and drag force. (2) the increase in the inclination angle has limited effect the aerodynamic forces. The inclination angles like corrug-3 and 4 produce almost the same forces.

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Aerodynamic effects of bio-inspired corrugated wings on gliding and hovering performances

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220917995 ◽

2020 ◽

pp. 095440622091799

Author(s):

Haibin Xuan ◽

Jun Hu ◽

Yong Yu ◽

Jiaolong Zhang

Keyword(s):

Inclination Angle ◽

Fluid Dynamic ◽

Angle Of Attack ◽

Aerodynamic Forces ◽

Limited Effect ◽

Gliding Flight ◽

Significant Difference ◽

Inclination Angles ◽

Underlying Mechanisms ◽

Lift And Drag

Recently, numerous studies have been conducted to clarify the effects of corrugation wing on aerodynamic performances. The effects of the corrugation patterns and inclination angles were investigated using computational fluid dynamic method in gliding and hovering flight at Reynolds numbers of order 104. The instantaneous aerodynamic forces and the vorticity field around the wing models were provided to research the underlying mechanisms of aerodynamic effects of corrugated wing models. The findings can be concluded as follows: (1) the corrugation patterns have different effects on aerodynamic performance. The effect of noncamber corrugated wing is to decrease the lift and increase drag compared with a flat-plate when the angle of attack is less than 25° during gliding flight. The corrugated wing with a camber (corrug-2) after the valleys enhances the aerodynamic forces when angle of attack is higher than 35°. The valley inclination angle has limited effect on aerodynamic forces in gliding flight. (2) The lift forces of different corrugation patterns show significantly asymmetric during the upstroke and downstroke. The main reason leads to this phenomenon is the case that two sides of the corrugated wings are not symmetric around the pitching axis. The corrugated wing with only two valleys (corrug-1) changes the lift and drag very slightly. Corrug-2 produces larger peak during downstroke and smaller peak during upstroke. The increase in the inclination angle has limited effect on the aerodynamic forces. The possible reason for these small aerodynamic effects might be that the corrugated wings are smoothed by small vortices trapped in valleys. The main reason for the significant difference between plate and corrug-2 is that the recirculating vortices trapped in the saddle and hump reduce the pressure above the wing surface.

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Aerodynamic Analysis of a Flapping Wing Aircraft for Short Landing

Applied Sciences ◽

10.3390/app10103404 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3404

Author(s):

Bing Ji ◽

Zenggang Zhu ◽

Shijun Guo ◽

Si Chen ◽

Qiaolin Zhu ◽

...

Keyword(s):

Aerodynamic Characteristics ◽

Flapping Wing ◽

Aerodynamic Analysis ◽

Drag Forces ◽

Wing Model ◽

Aerodynamic Model ◽

Computational Fluid Dynamics Cfd ◽

The Difference ◽

Cfd Method ◽

Lift And Drag

An investigation into the aerodynamic characteristics has been presented for a bio-inspired flapping wing aircraft. Firstly, a mechanism has been developed to transform the usual rotation powered by a motor to a combined flapping and pitching motion of the flapping wing. Secondly, an experimental model of the flapping wing aircraft has been built and tested to measure the motion and aerodynamic forces produced by the flapping wing. Thirdly, aerodynamic analysis is carried out based on the measured motion of the flapping wing model using an unsteady aerodynamic model (UAM) and validated by a computational fluid dynamics (CFD) method. The difference of the average lift force between the UAM and CFD method is 1.3%, and the difference between the UAM and experimental results is 18%. In addition, a parametric study is carried out by employing the UAM method to analyze the effect of variations of the pitching angle on the aerodynamic lift and drag forces. According to the study, the pitching amplitude for maximum lift is in the range of 60°~70° as the flight velocity decreases from 5 m/s to 1 m/s during landing.

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CFD Simulation Study of Gas-Liquid Flow Regimes in Inclined Wellbore

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.915-916.126 ◽

2014 ◽

Vol 915-916 ◽

pp. 126-130

Author(s):

Yin Di Zhang ◽

Long Fei Ruan ◽

De Hua Liu

Keyword(s):

Inclination Angle ◽

Cfd Simulation ◽

Fluid Dynamic ◽

Flow Regimes ◽

Two Phase ◽

Flow Rates ◽

Flow Regime Transition ◽

Gas Liquid Flow ◽

Cfd Method ◽

Good Agreement

Computational Fluid Dynamic (CFD) was used to investigate gas-liquid two phase flow regimes for the inclined wells. The simulation results were compared with the Taitel chart. A good agreement between the prediction and the Taitel flow regimes shows that CFD method can reasonably predict flow regimes in the inclined well. Another further study was conducted to explore the influence of flow rates and inclination angle on flow regimes. The results show both of flow rates and inclination angle have a significant effect on flow regime transition.

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Vortex Generators Contribution to the Enhancement of the Aerodynamic Performances

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.950.268 ◽

2014 ◽

Vol 950 ◽

pp. 268-274

Author(s):

Hocine Tebbiche ◽

Mohamed S. Boutoudj

Keyword(s):

Wind Tunnel ◽

Flow Control ◽

Leading Edge ◽

Reynolds Numbers ◽

Vortex Generators ◽

Drag Coefficients ◽

Passive Devices ◽

Aerodynamic Performances ◽

Lift And Drag ◽

Naca 0015

This study interest flow control using a new vortex generators (VGs) shape with counter-rotating vortices, obtained by adding a new element to a configuration mostly investigated. The experiments were performed in the aim to determine the VGs answer when placed on the suction face at 10% from the leading edge of an airfoil Naca 0015 in order to improve the lift and drag coefficients. The investigations were accomplished in wind tunnel for two Reynolds numbers and geometrical vortex generators configurations. The obtained results are analyzed according to several parameters such as the VG height, the space between the same VG pair and the additional factor. The results show a profit brought by the passive devices estimated at about 28% of the CL/Cd ratio.

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Design Optimization and Analysis of NACA 0012 Airfoil Using Computational Fluid Dynamics and Genetic Algorithm

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.664.111 ◽

2014 ◽

Vol 664 ◽

pp. 111-116 ◽

Cited By ~ 6

Author(s):

R.K. Ganesh Ram ◽

Yashaan Nari Cooper ◽

Vishank Bhatia ◽

R. Karthikeyan ◽

C. Periasamy

Keyword(s):

Reynolds Numbers ◽

Ansys Fluent ◽

Airfoil Optimization ◽

Drag Forces ◽

Fluent Software ◽

Numerical Computing ◽

Cfd Method ◽

Lift And Drag ◽

Naca 0012 ◽

Mathematical Relations

CFD method is inexpensive method of analysis of flow over aerodynamic structure. It incorporates mathematical relations and algorithms to analyze and solve the problems regarding fluid flow. CFD analysis of an airfoil produces results such as lift and drag forces which determines the ability of an airfoil. Optimization of an airfoil involves improving the design of the airfoil in order to manipulate the lift and drag coefficients according to the requirements. It is a very common method used in all fields of engineering. MATLAB is a numerical computing environment which supports interface with other software. XFoil is airfoil analysis software which calculates the lift and drag characteristics for different Reynolds numbers, Mach numbers and angles of attack. MALAB is interfaced with XFoil and the optimization of NACA 0012 airfoil is done and the results are analyzed. The performance of optimized air foil is analyzed using ANSYS FLUENT software.

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EXPERIMENTAL STUDY OF THE EFFECT OF THE WAKE GENERATED BY OSCILLATING GURNEY FLAP

Latin American Applied Research - An international journal ◽

10.52292/j.laar.2019.67 ◽

2019 ◽

Vol 49 (4) ◽

pp. 289-296

Author(s):

Julio Marañon Di Leo ◽

M. A. Martínez ◽

J. S. Delnero ◽

M. O. García Saínz

Keyword(s):

Flow Control ◽

Fluid Dynamic ◽

Reynolds Numbers ◽

Lower Surface ◽

Wing Model ◽

Flow Control Devices ◽

Integral Scales ◽

Gurney Flap ◽

Dynamic Structures ◽

General Configuration

The study of the turbulent near wake of an airfoil provided with flow control devices shows the flow configuration in such conditions and the starting vortices mechanism, while, the far wake offers information about the general performance of the model. The objective of the present work is to study the develop of the fluid-dynamic structures found in the NACA 4412 airfoil wake, as well as the development of the same structures when flow con-trol techniques are applied by means of a oscillating Gurney Flap place in the lower surface of the wing model, close to the trailing edge. Tests were per-formed at a given Reynolds numbers and the flow control system was set at different frequencies. In order to study the effect of the control mechanism on the wake, hot wire anemometry techniques were used. Two components of the velocity vector were measured - longitudinal and vertical - by means of a vertical array of three sensors acquiring simulta-neously. The intention is to quantify the flow general configuration at the airfoil wake for different test conditions. The velocity vectors will be analyzed, together with the turbulence intensity and integral scales.

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Acoustic Emission Characteristics and Joint Nonlinear Mechanical Response of Rock Masses under Uniaxial Compression

Energies ◽

10.3390/en14010200 ◽

2021 ◽

Vol 14 (1) ◽

pp. 200

Author(s):

Zhongliang Feng ◽

Xin Chen ◽

Yu Fu ◽

Shaoshuai Qing ◽

Tongguan Xie

Keyword(s):

Acoustic Emission ◽

Uniaxial Compression ◽

Inclination Angle ◽

Failure Modes ◽

Strain Curve ◽

Particle Flow Code ◽

Rock Masses ◽

Physical Experiments ◽

Inclination Angles ◽

Joint Inclination

The joint arrangement in rock masses is the critical factor controlling the stability of rock structures in underground geotechnical engineering. In this study, the influence of the joint inclination angle on the mechanical behavior of jointed rock masses under uniaxial compression was investigated. Physical model laboratory experiments were conducted on jointed specimens with a single pre-existing flaw inclined at 0°, 30°, 45°, 60°, and 90° and on intact specimens. The acoustic emission (AE) signals were monitored during the loading process, which revealed that there is a correlation between the AE characteristics and the failure modes of the jointed specimens with different inclination angles. In addition, particle flow code (PFC) modeling was carried out to reproduce the phenomena observed in the physical experiments. According to the numerical results, the AE phenomenon was basically the same as that observed in the physical experiments. The response of the pre-existing joint mainly involved three stages: (I) the closing of the joint; (II) the strength mobilization of the joint; and (III) the reopening of the joint. Moreover, the response of the pre-existing joint was closely related to the joint’s inclination. As the joint inclination angle increased, the strength mobilization stage of the joint gradually shifted from the pre-peak stage of the stress–strain curve to the post-peak stage. In addition, the instantaneous drop in the average joint system aperture (aave) in the specimens with medium and high inclination angles corresponded to a rapid increase in the form of the pulse of the AE activity during the strength mobilization stage.

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Fish larvae exploit edge vortices along their dorsal and ventral fin folds to propel themselves

Journal of The Royal Society Interface ◽

10.1098/rsif.2016.0068 ◽

2016 ◽

Vol 13 (116) ◽

pp. 20160068 ◽

Cited By ~ 16

Author(s):

Gen Li ◽

Ulrike K. Müller ◽

Johan L. van Leeuwen ◽

Hao Liu

Keyword(s):

Larval Fish ◽

Fish Larvae ◽

Fluid Dynamic ◽

Three Dimensional ◽

Reynolds Numbers ◽

Bony Fish ◽

The Body ◽

Functional Explanation ◽

Image Velocimetry ◽

Median Fins

Larvae of bony fish swim in the intermediate Reynolds number ( Re ) regime, using body- and caudal-fin undulation to propel themselves. They share a median fin fold that transforms into separate median fins as they grow into juveniles. The fin fold was suggested to be an adaption for locomotion in the intermediate Reynolds regime, but its fluid-dynamic role is still enigmatic. Using three-dimensional fluid-dynamic computations, we quantified the swimming trajectory from body-shape changes during cyclic swimming of larval fish. We predicted unsteady vortices around the upper and lower edges of the fin fold, and identified similar vortices around real larvae with particle image velocimetry. We show that thrust contributions on the body peak adjacent to the upper and lower edges of the fin fold where large left–right pressure differences occur in concert with the periodical generation and shedding of edge vortices. The fin fold enhances effective flow separation and drag-based thrust. Along the body, net thrust is generated in multiple zones posterior to the centre of mass. Counterfactual simulations exploring the effect of having a fin fold across a range of Reynolds numbers show that the fin fold helps larvae achieve high swimming speeds, yet requires high power. We conclude that propulsion in larval fish partly relies on unsteady high-intensity vortices along the upper and lower edges of the fin fold, providing a functional explanation for the omnipresence of the fin fold in bony-fish larvae.

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Turbulent Transport in Pin Fin Arrays: Experimental Data and Predictions

Volume 3: Turbo Expo 2005, Parts A and B ◽

10.1115/gt2005-68180 ◽

2005 ◽

Cited By ~ 4

Author(s):

F. E. Ames ◽

L. A. Dvorak

Keyword(s):

Heat Transfer ◽

Fluid Dynamics ◽

Boundary Layers ◽

Fluid Dynamic ◽

Turbulent Transport ◽

Turbulence Models ◽

Reynolds Numbers ◽

Velocity Profiles ◽

Pin Fin ◽

Pin Fin Arrays

The objective of this research has been to experimentally investigate the fluid dynamics of pin fin arrays in order to clarify the physics of heat transfer enhancement and uncover problems in conventional turbulence models. The fluid dynamics of a staggered pin fin array have been studied using hot wire anemometry with both single and x-wire probes at array Reynolds numbers of 3000; 10,000; and 30,000. Velocity distributions off the endwall and pin surface have been acquired and analyzed to investigate turbulent transport in pin fin arrays. Well resolved 3-D calculations have been performed using a commercial code with conventional two-equation turbulence models. Predictive comparisons have been made with fluid dynamic data. In early rows where turbulence is low, the strength of shedding increases dramatically with increasing in Reynolds numbers. The laminar velocity profiles off the surface of pins show evidence of unsteady separation in early rows. In row three and beyond laminar boundary layers off pins are quite similar. Velocity profiles off endwalls are strongly affected by the proximity of pins and turbulent transport. At the low Reynolds numbers, the turbulent transport and acceleration keep boundary layers thin. Endwall boundary layers at higher Reynolds numbers exhibit very high levels of skin friction enhancement. Well resolved 3-D steady calculations were made with several two-equation turbulence models and compared with experimental fluid mechanic and heat transfer data. The quality of the predictive comparison was substantially affected by the turbulence model and near wall methodology.

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