Numerical Study on the Unsteady-Force-Generation Mechanism of Insect Flapping Motion

AIAA Journal ◽  
2008 ◽  
Vol 46 (7) ◽  
pp. 1835-1848 ◽  
Author(s):  
Jung-Sang Lee ◽  
Jin-Ho Kim ◽  
Chongam Kim
Keyword(s):  
Numerical Study ◽  
Generation Mechanism ◽  
Force Generation ◽  
Flapping Motion ◽  
Unsteady Force

Unsteady aerodynamic force generation by a model fruit fly wing in flapping motion

2002 ◽  
Vol 205 (1) ◽  
pp. 55-70 ◽  
Author(s):  
Mao Sun ◽  
Jian Tang
Keyword(s):  
Aerodynamic Force ◽  
Lift Coefficient ◽  
Unsteady Aerodynamics ◽  
Fruit Fly ◽  
Force Generation ◽  
Generation Process ◽  
Flapping Motion ◽  
Unsteady Aerodynamic ◽  
The Mean ◽  
Unsteady Aerodynamic Force

SUMMARY A computational fluid-dynamic analysis was conducted to study the unsteady aerodynamics of a model fruit fly wing. The wing performs an idealized flapping motion that emulates the wing motion of a fruit fly in normal hovering flight. The Navier–Stokes equations are solved numerically. The solution provides the flow and pressure fields, from which the aerodynamic forces and vorticity wake structure are obtained. Insights into the unsteady aerodynamic force generation process are gained from the force and flow-structure information. Considerable lift can be produced when the majority of the wing rotation is conducted near the end of a stroke or wing rotation precedes stroke reversal (rotation advanced), and the mean lift coefficient can be more than twice the quasi-steady value. Three mechanisms are responsible for the large lift: the rapid acceleration of the wing at the beginning of a stroke, the absence of stall during the stroke and the fast pitching-up rotation of the wing near the end of the stroke. When half the wing rotation is conducted near the end of a stroke and half at the beginning of the next stroke (symmetrical rotation), the lift at the beginning and near the end of a stroke becomes smaller because the effects of the first and third mechanisms above are reduced. The mean lift coefficient is smaller than that of the rotation-advanced case, but is still 80 % larger than the quasi-steady value. When the majority of the rotation is delayed until the beginning of the next stroke (rotation delayed), the lift at the beginning and near the end of a stroke becomes very small or even negative because the effect of the first mechanism above is cancelled and the third mechanism does not apply in this case. The mean lift coefficient is much smaller than in the other two cases.

Numerical Study on Pressure Generation Mechanism of Oil Film under Oil Control Ring

2019 ◽  
Author(s):  
Susumu Degawa ◽  
Wataru Kobayashi ◽  
Koji Kikuhara ◽  
Koichi Nishibe ◽  
Akemi Ito
Keyword(s):  
Numerical Study ◽  
Generation Mechanism ◽  
Oil Film

Force Generation Mechanism of a Wing Model in Drosophila Voluntary Take-Off

2011 ◽  
Author(s):  
Q. Zhang ◽  
R. H. Wen ◽  
H. Liu ◽  
Jiachun Li ◽  
Song Fu
Keyword(s):  
Generation Mechanism ◽  
Force Generation ◽  
Wing Model

Investigation on Aeroacoustics and Aerodynamics of the Stator Lean Effect for Rotor-Stator Interaction

2013 ◽  
Author(s):  
Hai-jian Liu ◽  
Hua Ouyang ◽  
Ya-dong Wu ◽  
Jie Tian ◽  
Zhao-hui Du
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Phase Lag ◽  
Axial Thrust ◽  
Unsteady Force ◽  
Lean Angle ◽  
Rotor Stator Interaction ◽  
Stator Blade ◽  
Unsteady Loading ◽  
Thrust And Torque

The rotor-stator interaction in a 1.5 stage compressor with different lean angle of downstream stator blades was investigated by aeroacoustic and numerical study. The aeroacoustic performance with narrow spectra, the sound pressure level distribution and the unsteady loading of the compressor were tested and analyzed. The RMS pressure, the axial thrust and torque of the downstream stator blade distribution revealed the unsteady characteristic of rotor-stator interaction at different downstream stator blade lean angle. The positive lean stator had better noise constraint than the negative lean stator. However, the RMS pressure and the unsteady force increased with the increase of the lean angle when the stator had positive lean angle. The time-spatial contours of the axial velocity demonstrated the effect of time delay for the rotor wake intersection with the leading edge of the stator blade. And the phase lag distribution of the wake presented the detail distribution of the wake phase along the span. The downstream stator blade lean was effective to obtain a significant reduction for the unsteady force and get large phase lag for the rotor’s wake of rotor-stator interaction. Leaned positive blade had better benefits than negative for the noise reduction and the phase lag of the wake.

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