scholarly journals Clap-and-fling mechanism in a hovering insect-like two-winged flapping-wing micro air vehicle

2016 ◽  
Vol 3 (12) ◽  
pp. 160746 ◽  
Author(s):  
Hoang Vu Phan ◽  
Thi Kim Loan Au ◽  
Hoon Cheol Park
Keyword(s):  
Drag Force ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Force Generation ◽  
Vertical Force ◽  
Cfd Model ◽  
Air Vehicle

This study used numerical and experimental approaches to investigate the role played by the clap-and-fling mechanism in enhancing force generation in hovering insect-like two-winged flapping-wing micro air vehicle (FW-MAV). The flapping mechanism was designed to symmetrically flap wings at a high flapping amplitude of approximately 192°. The clap-and-fling mechanisms were thereby implemented at both dorsal and ventral stroke reversals. A computational fluid dynamic (CFD) model was constructed based on three-dimensional wing kinematics to estimate the force generation, which was validated by the measured forces using a 6-axis load cell. The computed forces proved that the CFD model provided reasonable estimation with differences less than 8%, when compared with the measured forces. The measurement indicated that the clap and flings at both the stroke reversals augmented the average vertical force by 16.2% when compared with the force without the clap-and-fling effect. In the CFD simulation, the clap and flings enhanced the vertical force by 11.5% and horizontal drag force by 18.4%. The observations indicated that both the fling and the clap contributed to the augmented vertical force by 62.6% and 37.4%, respectively, and to the augmented horizontal drag force by 71.7% and 28.3%, respectively. The flow structures suggested that a strong downwash was expelled from the opening gap between the trailing edges during the fling as well as the clap at each stroke reversal. In addition to the fling phases, the influx of air into the low-pressure region between the wings from the leading edges also significantly contributed to augmentation of the vertical force. The study conducted for high Reynolds numbers also confirmed that the effect of the clap and fling was insignificant when the minimum distance between the two wings exceeded 1.2c (c = wing chord). Thus, the clap and flings were successfully implemented in the FW-MAV, and there was a significant improvement in the vertical force.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2008 ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

Design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely lightweight designs that accomplish these motions of the wing, using just a single, or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

scholarly journals First principle analysis of Coandă Micro Air Vehicle aerodynamic forces for preliminary sizing

2017 ◽  
Vol 89 (2) ◽  
pp. 231-245
Author(s):  
Harijono Djojodihardjo ◽  
Riyadh Ibraheem Ahmed ◽  
Abd Rahim Abu Talib ◽  
Azmin Shakrine Mohd Rafie
Keyword(s):  
Mathematical Models ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Practical Interest ◽  
Micro Air Vehicle ◽  
Radius Of Curvature ◽  
Geometrical Parameters ◽  
Content Type ◽  
Air Vehicle ◽  
Coanda Jet

Purpose The purpose of this paper is to reformulate the governing equations incorporating major variables and parameters for the design a Micro Air Vehicle (MAV), to meet the desired mission and design requirements. Design/methodology/approach Mathematical models for various spherical and cylindrical Coandă MAV configurations were rederived from first principles, and the performance measures were defined. To verify the theoretical prediction to a certain extent, a computational fluid dynamic (CFD) simulation for a Coandă MAV generic models was performed. Findings The major variables and parameters of Coandă MAV have been formulated into practical guidelines, which relate the lift (or thrust) produced for certain input variables, particularly the Coandă MAV jet momentum coefficient. The influences of the geometrical parameters are elaborated. Research limitations/implications The present analysis on Coandă jet-configured MAV is focused on the lift generation due to the Coandă jet effect through a meticulous analysis. The effects of viscosity, the Coandă jet thickness, the radius of curvature of the surface and the stability of Coandă jet are not considered and will be the subject of the following work. Practical implications The results obtained can be used for sizing in the preliminary design of Coandă MAVs. Originality/value Physical and mathematical models were developed which can describe the physical phenomena of the flow field near the Coandă MAV surfaces influenced by Coandă jet sheets and for obtaining a relationship between relevant variables and parameters to the lift of practical interest.

Implementation of initial passive stability in insect-mimicking flapping-wing micro air vehicle

2015 ◽  
Vol 3 (1) ◽  
pp. 18-38 ◽  
Author(s):  
Hoang Vu Phan ◽  
Quang-Tri Truong ◽  
Hoon-Cheol Park
Keyword(s):  
Aerodynamic Force ◽  
Three Dimensional ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Content Type ◽  
Wing Kinematics ◽  
Blade Element Theory ◽  
Air Vehicle ◽  
The Mean ◽  
Vertical Takeoff

Purpose – The purpose of this paper is to demonstrate the uncontrolled vertical takeoff of an insect-mimicking flapping-wing micro air vehicle (FW-MAV) of 12.5 cm wing span with a body weight of 7.36 g after installing batteries and power control. Design/methodology/approach – The forces were measured using a load cell and estimated by the unsteady blade element theory (UBET), which is based on full three-dimensional wing kinematics. In addition, the mean aerodynamic force center (AC) was determined based on the UBET calculations using the measured wing kinematics. Findings – The wing flapping frequency can reach to 43 Hz at the flapping angle of 150°. By flapping wings at a frequency of 34 Hz, the FW-MAV can produce enough thrust to over its own weight. For this condition, the difference between the estimated and average measured vertical forces was about 7.3 percent with respect to the estimated force. All parts for the FW-MAV were integrated such that the distance between the mean AC and the center of gravity is close to zero. In this manner, pitching moment generation was prevented to facilitate stable vertical takeoff. An uncontrolled takeoff test successfully demonstrated that the FW-MAV possesses initial pitching stability for takeoff. Originality/value – This work has successfully demonstrated an insect-mimicking flapping-wing MAV that can stably takeoff with initial stability.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2010 ◽  
Vol 2 (2) ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Light Weight ◽  
Aerodynamic Forces ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

The design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely light-weight designs that accomplish these motions of the wing, using just a single or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

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