Structure and aerodynamic characteristics of a coaxial quad-wing flapper

2020 ◽  
pp. 095441002096754
Author(s):  
Huan Shen ◽  
Qian Li ◽  
Kun Hu ◽  
Zhuoqun Feng ◽  
Aihong Ji
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Simulation Study ◽  
Theoretical Basis ◽  
Elevation Angle ◽  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Driving Mechanism ◽  
Wing Movement ◽  
Motion Parameters

As a special type of micro ornithopter, the coaxial quad-wing flapper (CQWF) enables greater flight speed and higher stability than the paired-wing flapper. These characteristics are closely related to the unique pneumatic mechanism of the CQWF. Therefore, the aerodynamic generation mechanism of the CQWFs has been actively researched in recent years. This study verifies the reliability of flow-field simulations in a CQWF prototype with an aerodynamically optimized driving mechanism. For the selected motion parameters and shape dimensions of the flapping-wing aircraft, the vorticity fields at different elevation angles are observed in flow-field simulations. The elevation angle strongly affects the lift. Moreover, the wing movement based on the Clap–Fling mechanism significantly affected the acquisition of the lift, which explains the higher stability of the CQWF than that of the paired-wing flapper and provides a theoretical basis for the optimization of the flapping prototype. When tested on a wind-tunnel platform, the prototype yields slightly higher lift compared with those obtained in the simulation study. In addition to confirming the phenomenon revealed in flow visualization, it also showed that the unsteady mechanism of the two-pair wing is more powerful than calculated.

Influence of Regulating Seam on Aerodynamic Characteristics of Virtual Wind Tunnel

2013 ◽  
Vol 774-776 ◽  
pp. 290-294
Author(s):  
Xing Jun Hu ◽  
Lei Yue
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Theoretical Basis ◽  
Aerodynamic Characteristics ◽  
Wind Tunnel Model ◽  
Open Type ◽  
Car Model ◽  
Tunnel Model ◽  
Simulation Results

A digital car model was taken as study object, and the influence of the regulating seam to an open type automobile wind tunnel was discussed by comparing simulation results with test data.The results show that the regulating seam changes the flow field around the collector, reduces the size of unsteady flow field and the flow in test section is uniformed better. Thus, the regulating seam shouldn’t be removed when simplifying the wind tunnel model in the simulation. This conclusion will provide theoretical basis and data support for better virtual reproduction and numerical simulation of a wind tunnel.

A Design of Innovative Experiment Platform Based on the Research of Flapping-Wing Aircraft

2014 ◽  
Vol 651-653 ◽  
pp. 587-592
Author(s):  
Bing Hao Zhu ◽  
Xiao Yi Jin ◽  
Li Li Zhao ◽  
Jing Yuan Zhang ◽  
Hua Cheng Tao
Keyword(s):  
Mechanism Design ◽  
Flapping Wing ◽  
Driving Mechanism ◽  
Experimental Platform ◽  
Experiment Platform ◽  
Design And Implementation ◽  
Design Scheme ◽  
Development Processes ◽  
Motion Parameters ◽  
Platform System

According to the fact that it need several tests to determine the size and motion parameters of the flapping-wing aircraft in the development processes, the paper proposed a design scheme of flapping wing system experimental platform. Separately from the scheme, the system platform, driving mechanism design, motion parameters change, described in detail the design and implementation of this innovation experiment platform. Users can simulate and debug the platform system to determine the performance of the flapping-wing mechanism.

scholarly journals Numerical method for an assessment of steady and motion-excited flowfields in a transonic cascade wind tunnel

2017 ◽  
Vol 1 ◽  
pp. QL9XVI ◽  
Author(s):  
Atsushi Tateishi ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Seiji Uzawa
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Numerical Method ◽  
Aerodynamic Characteristics ◽  
Pressure Amplitude ◽  
Tunnel Wall ◽  
Flow Simulations ◽  
Influence Coefficients ◽  
The Difference ◽  
Transonic Cascade

AbstractThis article presents a numerical method and its application for an assessment of the flow field inside a wind tunnel. A structured computational fluid dynamics (CFDs) solver with overset mesh technique is developed in order to simulate geometrically complex configurations. Applying the developed solver, a whole transonic cascade wind tunnel is modeled and simulated by a two-dimensional manner. The upstream and downstream periodicity of the cascade and the effect of the tunnel wall on the unsteady flow field are focused on. From the steady flow simulations, the existence of an optimum throttle position for the best periodicity for each tailboard angle is shown, which provides appropriate aerodynamic characteristics of ideal cascades in the wind tunnel environment. Unsteady simulations with blade oscillation is also conducted, and the difference in the influence coefficients between ideal and wind tunnel configurations becomes large when the pressure amplitude increases on the lower blades.

LIFT PERFORMANCE OF A CAMBERED WING FOR AERODYNAMIC PERFORMANCE ENHANCEMENT OF THE FLAPPING WING

2015 ◽  
Vol 75 (8) ◽  
Author(s):  
H. Yusoff ◽  
N. Iswadi ◽  
A.H. Zulkifly ◽  
Sh. Mohd Firdaus ◽  
M.Z. Abdullah ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Performance Enhancement ◽  
Wind Tunnel Test ◽  
Micro Air Vehicles ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Open Circuit ◽  
Flapping Wing ◽  
Flapping Flight ◽  
Advance Ratio

Flapping-Wing Micro Air Vehicles (FW-MAVs) are small hand-held flying vehicles that can maneuver in constrained space owing to its lightweight, low aspect ratio and the ability to fly in low Reynolds number environment. In this study, the aerodynamic characteristics such as time-averaged lift of camber wings with different five wind tunnel test models with 6, 9, 12, and 15 percent camber were developed and the results were compared with time-averaged lift of a flat wing in order to assess the effects of camber wing on the aerodynamic performance for flapping flight applications. The experiments were performed in an open circuit wind tunnel with of non-return airflow with a test section of (0.3 x 0.3) m and capable of speeds from 0.5 to 30 m/s. The time-averaged lift as functions of advance ratio of the flapping motions with respect to the incoming flows are measured by using a strain gauge balance and KYOWA PCD-300A sensor interface data acquisition system. It is found that camber would bring significant aerodynamic benefits when the flapping flight is in unsteady state regime, with advance ratio less than 1.0. The aerodynamic benefits of camber are found to decay exponentially with the increasing advance ratio. Cambered wing shows significantly higher lift in comparison to the flat wing.

Unsteady Aerodynamic Characteristics of a High Speed Train with Crosswind

2011 ◽  
Vol 66-68 ◽  
pp. 1878-1882
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Chen Guang Fan ◽  
Li Lu
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Vehicle Speed ◽  
High Speed Train ◽  
Mesh Method

The aerodynamic performances of a high speed train will significant change under the action of the crosswind. Large eddy simulation (LES) was made to solve the flow around a simplified CRH2 high speed train with 250km/h and 350km/h under the influence of a crosswind with 28.4m/s base on the finite volume method and dynamic layering mesh method and three dimensional incompressible Navier-Stokes equations. Wind tunnel experimental method of static train with relative flowing air and dynamic mesh method of moving train were compared. The results of numerical simulation show that the flow field around train is completely different between Wind tunnel experiment and factual running. Many vortices will be produced on the leeside of the train with alternately vehicle bottom and back under the influence of a crosswind. The flow field around train is similar with different vehicle speed.

Simulation of Interference Characteristics of the Model Supporting Beams with Different Forms of Section in Wind Tunnel Test

2014 ◽  
Vol 1025-1026 ◽  
pp. 910-913
Author(s):  
Xing Jun Hu ◽  
Yue Xing Miao
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Three Dimensional Flow ◽  
Ansys Fluent ◽  
Correction Error ◽  
Dimensional Flow ◽  
Pressure Distributions

In order to study the effects of the supporting beams with different forms of section on the aerodynamic characteristics of car models. Model supporting beams with three different forms of section were designed based on standard MIRA model. The commercial CFD software - Ansys Fluent was used to simulate the three-dimensional flow field around the standard MIRA model installed with three different kinds of supporting beams. With comparisons between the drag coefficients, pressure distributions and velocity distributions around the wheels with the different supporting beams, the reasons for the differences in aerodynamics are analyzed and advices were given for helping choosing the supporting beam with minimal disturbance to reduce the correction error.

Aerodynamic characteristics of the wings and body of a dragonfly

1996 ◽  
Vol 199 (2) ◽  
pp. 281-294 ◽  
Author(s):  
M Okamoto ◽  
K Yasuda ◽  
A Azuma
Keyword(s):  
Surface Roughness ◽  
Wind Tunnel ◽  
Flow Field ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Free Flight ◽  
Flight Tests ◽  
Dragonfly Wings ◽  
Artificial Wing

The aerodynamic characteristics of the wings and body of a dragonfly and of artificial wing models were studied by conducting two types of wind-tunnel tests and a number of free-flight tests of gliders made using dragonfly wings. The results were consistent between these different tests. The effects of camber, thickness, sharpness of the leading edge and surface roughness on the aerodynamic characteristics of the wings were characterized in the flow field with Reynolds numbers (Re) as low as 103 to 104.

Characteristic model-based adaptive control for cryogenic wind tunnels

2020 ◽  
pp. 014233122096065
Author(s):  
Chenhui Yu ◽  
Fei Liao ◽  
Haibo Ji ◽  
Wenhua Wu
Keyword(s):  
Reynolds Number ◽  
Wind Tunnel ◽  
Flow Field ◽  
Control Problem ◽  
Mimo System ◽  
Adaptive Controller ◽  
Characteristic Model ◽  
Model Based ◽  
Field Control ◽  
Cryogenic Wind Tunnel

With the increasing requirement of Reynolds number simulation in wind tunnel tests, the cryogenic wind tunnel is considered as a feasible method to realize high Reynolds number. Characteristic model-based adaptive controller design method is introduced to flow field control problem of the cryogenic wind tunnel. A class of nonlinear multi-input multi-output (MIMO) system is given for theoretical research that is related to flow field control of the cryogenic wind tunnel. The characteristic model in the form of second-order time-varying difference equations is provided to represent the system. A characteristic model-based adaptive controller is also designed correspondingly. The stability analysis of the closed loop system composed of the characteristic model or the exact discrete-time model and the proposed controller is investigated respectively. Numerical simulation is presented to illustrate the effectiveness of this control method. The modeling and control problem based on characteristic model method for a class of MIMO system are studied and first applied to the cryogenic wind tunnel control field.

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