Unsteady Pressure Distribution of a Flapping Wing Undergoing Root Flapping Motion with Elbow Joint at Different Reduced Frequencies

2017 ◽  
Vol 10 (3) ◽  
pp. 105
Author(s):  
Ahmad F. Razaami ◽  
M. K. H. M. Zorkipli ◽  
H. C. Lai ◽  
M. Z. Abdullah ◽  
Norizham Abdul Razak
Keyword(s):  
Pressure Distribution ◽  
Elbow Joint ◽  
Flapping Wing ◽  
Flapping Motion ◽  
Unsteady Pressure

Flight Characteristics of Flapping Wing Miniature Air Vehicles With “Figure-8” Spherical Motion

2009 ◽  
Author(s):  
Mohamed B. Trabia ◽  
Woosoon Yim ◽  
Zohaib Rehmat ◽  
Jesse Roll
Keyword(s):  
Mathematical Model ◽  
Wind Tunnel ◽  
Experimental Testing ◽  
Flapping Wing ◽  
Dynamic Stall ◽  
Wind Tunnel Testing ◽  
Servo Motor ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Spherical Motion

Hummingbirds and some insects exhibit “Figure-8” flapping motion that allows them to go through a variety of maneuvers including hovering. Understanding the flight characteristics of Figure-8 flapping motion can potentially yield the foundation of flapping wing UAVs that can experience similar maneuverability. In this paper, a mathematical model of the dynamic and aerodynamic forces associated with Figure-8 motion generated by a spherical four bar mechanism is developed. For validation, a FWMAV prototype with the wing attached to a coupler point and driven by a DC servo motor is created for experimental testing. Wind tunnel testing is conducted to determine the coefficients of flight and the effects of dynamic stall. The wing is driven at speeds up to 12.25 Hz with results compared to that of the model. The results indicate good correlation between mathematical model and experimental prototype.

Effects of Blade Counts and Clocking on the Unsteady Profile Pressure Distribution in an Axial-Radial Combined Compressor

2013 ◽  
Author(s):  
Ben Zhao ◽  
Ce Yang ◽  
Liangjun Hu ◽  
Dazhong Lao
Keyword(s):  
Numerical Simulation ◽  
Data Analysis ◽  
Pressure Distribution ◽  
Pressure Fluctuations ◽  
Blade Surface ◽  
Analysis Method ◽  
Unsteady Pressure ◽  
Stator Blade ◽  
Multistage Compressor ◽  
New Hypothesis

A new hypothesis is presented for the superimposed effects of the blade pressure distribution in a multistage compressor. The effects of the unsteady pressure fluctuations on the blade surface are separated into three groups. The influences of the upstream or downstream rotors can be obtained by numerical simulation for the R/S or S/R configuration; the data produced by all the influences can be obtained from the R/S/R configuration. The effects of the blade counts and clocking on the superimposed effects, acting on the profile pressure distribution, are studied using a special data analysis method that had been previously developed by the authors. The results indicate that the blade counts of the upstream and downstream rotors determine the periods of the unsteady pressure fluctuations on the stator surface. The clocking moving blade rows modulate the relative superimposed phases and interactions between two rotors such that the unsteady pressure fluctuates with different amplitudes on the surface of the stator blade.

Geometric Design of a Bio-Inspired Flapping Wing Mechanism Based on Bennett-Derived 6R Deployable Mechanisms

2014 ◽  
Author(s):  
Huang Hailin ◽  
Li Bing
Keyword(s):  
Flapping Wing ◽  
Geometric Design ◽  
Geometric Parameters ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Flapping Motion ◽  
Single Degree ◽  
Revolute Joints ◽  
Air Vehicle ◽  
Deployable Mechanism

In this paper, we present the concept of designing flapping wing air vehicle by using the deployable mechanisms. A novel deployable 6R mechanism, with the deploying/folding motion of which similar to the flapping motion of the vehicle, is first designed by adding two revolute joints in the adjacent two links of the deployable Bennett linkage. The mobility of this mechanism is analyzed based on a coplanar 2-twist screw system. An intuitive projective approach for the geometric design of the 6R deployable mechanism is proposed by projecting the joint axes on the deployed plane. Then the geometric parameters of the deployable mechanism can be determined. By using another 4R deployable Bennett connector, the two 6R deployable wing mechanisms can be connected together such that the whole flapping wing mechanism has a single degree of freedom (DOF).

Design of “Figure-8” Spherical Motion Flapping Wing for Miniature UAV

2009 ◽  
Author(s):  
Zohaib Rehmat ◽  
Jesse Roll ◽  
Joon S. Lee ◽  
Woosoon Yim ◽  
Mohamed B. Trabia
Keyword(s):  
Experimental Testing ◽  
Flapping Wing ◽  
Servo Motor ◽  
Flapping Motion ◽  
Experimental Prototype ◽  
Wing Motion ◽  
Air Vehicle ◽  
Spherical Motion

Hummingbirds and some insects exhibit a “Figure-8” flapping motion, which allows them to undergo variety of maneuvers including hovering. It is therefore desirable to have miniature air vehicle (FWMAV) with this wing motion. This paper presents a design of a flapping-wing for FWMAV that can mimic “Figure-8” motion using a spherical four bar mechanism. In the proposed design, the wing is attached to a coupler point on the mechanism, which is driven by a DC servo motor. A prototype is fabricated to verify that the design objectives are met. Experimental testing was conducted to determine the validity of the design. The results indicate good correlation between model and experimental prototype.

The Design of New Mechanism of Birdlike MAV

2012 ◽  
Vol 229-231 ◽  
pp. 470-473
Author(s):  
Hai Zhou Zhai
Keyword(s):  
Angular Velocity ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Flapping Motion ◽  
Folding Angle ◽  
Air Vehicle ◽  
Aerodynamic Property ◽  
Kinematic Performance

MAV- Micro Air Vehicle which acts like bird has attracted many studies because of outstanding aerodynamic property. Former studies on birdlike MAV with flapping wing had just focused on the flapping motion, but passed over the change of flapping angular velocity and deformation of wing, therefore lost the good aerodynamic capacity. One new mechanism of the birdlike MAV is designed and studied. The mechanism can bring out 3 motions at one time, including flapping, spanning and twisting, so has movement as bird. The kinematic performance including the flapping angle, flapping angular velocity, and the folding angle etc., has been studied and compared with other relative works. The design can help the birdlike aircraft into reality.

Experimental study of an unsteady pressure distribution in a closed hydraulic chamber

1986 ◽  
Vol 18 (9) ◽  
pp. 1266-1270
Author(s):  
P. P. Lepikhin ◽  
V. N. Storozhuk ◽  
N. I. Zelenyuk
Keyword(s):  
Experimental Study ◽  
Pressure Distribution ◽  
Unsteady Pressure

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.

The Blade Profile Orientations Effects on the Aeromechanics of Multirow Turbomachines

2015 ◽  
Vol 138 (6) ◽  
Author(s):  
M. T. Rahmati ◽  
L. He ◽  
Y. S. Li
Keyword(s):  
Pressure Distribution ◽  
Frequency Domain ◽  
Major Effect ◽  
Frequency Domain Method ◽  
Blade Profile ◽  
Unsteady Pressure ◽  
Aerodynamic Damping ◽  
Blade Row ◽  
Pressure Changes ◽  
Phase Angles

The aerodynamic damping calculations for turbomachinery blade aeromechanics applications are typically carried out in an isolated blade row. The aerodynamic damping of vibrating blades, however, can be significantly influenced by the presence of neighboring blade rows. A highly efficient frequency-domain method is used to investigate the multirow effects on the blade row aerodynamic damping of a compressor and turbine. Depending on the blade profile orientations, the flow reflection effects from adjacent blade rows can significantly alter both unsteady pressure amplitudes and phase angles. Therefore, the blade aerodamping might increase or decrease depending on the stabilizing or destabilizing effects of the unsteady pressure changes. In the case of the compressor, the downstream stator significantly changes the unsteady pressure distribution on the rotor thus, affects the rotor aerodamping. In the turbine case, the upstream stator has a major effect on the aerodamping, while the downstream stator does not significantly change the rotor aerodamping.

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