Modeling of Pitching and Plunging Airfoils at Reynolds Number between 1x10^4 and 6x10^4

Kang, Chang Kwon; Aono, Hikaru; Trizila, Pat; Baik, Yeon Sik; Rausch, Jonathan; Bernal, Luis P.; Ol, Michael V.; Shyy, Wei

doi:10.2514/6.2009-4100

Cited by 15 publications

(10 citation statements)

References 44 publications

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“…These double peak phenomena is observed at St greater than 0.2 and it becomes more apparent as St increases. The effective angle of attack profile used in current study ranges between -6° and 22°, and this particular profile has been explored in many studies [25,26,32,33]. The initial angle of attack is set at 8° and the angular amplitude considered is ±14°.…”

Section: A Airfoil Kinematicsmentioning

confidence: 99%

“…The St above 0.3 is of interest because many biological flyers operate at St between 0.25 and 0.35 [30], and this range of St is reported to produce optimum propulsive efficiency [31]. The Re based on chord for the present study is 5,000 and the effect of Re is expected to be negligible due to separation at the leading edge of the flat plate produced by the effective angle of attack profile [32,33]. Two force measurement techniques are used in this study.…”

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confidence: 94%

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Unsteady force generation and vortex dynamics of pitching and plunging aerofoils

et al. 2012

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Experimental studies of the flow topology, leading-edge vortex dynamics and unsteady force produced by pitching and plunging flat-plate aerofoils in forward flight at Reynolds numbers in the range 5000–20 000 are described. We consider the effects of varying frequency and plunge amplitude for the same effective angle-of-attack time history. The effective angle-of-attack history is a sinusoidal oscillation in the range $\ensuremath{-} 6$ to $2{2}^{\ensuremath{\circ} } $ with mean of ${8}^{\ensuremath{\circ} } $ and amplitude of $1{4}^{\ensuremath{\circ} } $. The reduced frequency is varied in the range 0.314–1.0 and the Strouhal number range is 0.10–0.48. Results show that for constant effective angle of attack, the flow evolution is independent of Strouhal number, and as the reduced frequency is increased the leading-edge vortex (LEV) separates later in phase during the downstroke. The LEV trajectory, circulation and area are reported. It is shown that the effective angle of attack and reduced frequency determine the flow evolution, and the Strouhal number is the main parameter determining the aerodynamic force acting on the aerofoil. At low Strouhal numbers, the lift coefficient is proportional to the effective angle of attack, indicating the validity of the quasi-steady approximation. Large values of force coefficients (${\ensuremath{\sim} }6$) are measured at high Strouhal number. The measurement results are compared with linear potential flow theory and found to be in reasonable agreement. During the downstroke, when the LEV is present, better agreement is found when the wake effect is ignored for both the lift and drag coefficients.

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Section: A Airfoil Kinematicsmentioning

confidence: 99%

mentioning

confidence: 94%

Unsteady force generation and vortex dynamics of pitching and plunging aerofoils

et al. 2012

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“…Shyy and Liu As for the filtering process for LES, spatial filtering technique is employed on the unsteady Navier Stokes equations in three dimensional spaces and removes the scales of wave-numbers higher than the cut off wavenumber. The filter function G(x, x', ∆) is applied to the velocity field, the filtered velocity flow field is therefore can be represented as follow [37]:…”

Section: -2 Numerical Simulation For Turbulence Flow and Large Eddy mentioning

confidence: 99%

“…However, there are some shortcomings for the IB method; for example, similar to RANS solver; IB method is also having difficulty on handling geometry with sharp edges [37]. Apart from that, most of the IB techniques are having difficulty on the issue of mass-conserving at the moving boundary, and causes wiggles appear around the moving object and high frequency oscillation noise appeared on the forces and pressure curve.…”

Section: Figure 0-6 Pressure Boundary Conditionsmentioning

confidence: 99%

“…The aerodynamics of flapping wings is very hard to predict due to its non-linearity, unsteadiness of the flow and complex kinematic motions involved. Therefore, Liu (Liu, 2007) and Kang (Kang, Aono, Trizila, Baik, Michael, & Shyy, 2009) [20] & [37] concluded that, in order to predict flapping wing aerodynamics accurately, the only technique is to solve the unsteady Navier stoke equation.…”

Section: Chapter 6 Analytical Model For the Prediction Of Peak Lift Omentioning

confidence: 99%

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Experimental and computational study of flapping wing aerodynamics at low reynolds number

Chai¹

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Recent rapid developments in micro-sized Unmanned Aerial Vehicles (UAVs) and Underwater Vehicles (UWVs) have attracted renewed research interest in flapping wings aerodynamics. Due to the limitation of the size of these vehicles, complex motions employed by the birds and fishes have to be simplified as additional actuators are needed to perform the complex motions which will significantly increase the size of these vehicles. In addition, the study of flapping wings aerodynamic is challenging as the parameters involved that affecting the performance is huge. Therefore, this thesis investigates the feasibility of flapping wings with simplified kinematic motions as the propulsion system for the micro UAV or UWV and obtains the optimizing parameters for improving the flapping wings aerodynamics performance through experimental and numerical simulation approaches. A simple analytical model for predicting the lift with moderate accuracy is also developed. In conclusion, with comprehensive works conducted, a better understanding of the physics behind the flapping wings aerodynamics allows the translation of knowledge and creates great impact to the development of flapping wings micro UAV and UWV. II ACKNOWLEDGEMENTS Throughout the years of study, the very first person that the author would like to thanks is his supervisor, Prof. Jorg Uwe Schluter. Although the author transferred under his supervision only during the final year, Prof. Jorg Uwe Schluter guided him throughout the project patiently and even not giving up on him when the author face a series of problems in life during his final year of study. Besides that, Prof. Jorg Uwe Schluter has helped the author to solve not only financial problem, also has provided a lot of advises to the author for tackling the difficulty. The candidate also wishes to express gratitude to his parents and siblings for strong mental support. Besides that, he would also wish to thanks to Prof Spot, who is his ex-supervisor, for his great helps during the beginning of his study; he also wish to take this chance to express his appreciation to Prof Simon Yu, Prof Ooi and Prof Daniel New for providing thousands of precious advices. The author also treasures the opportunity that given from the school (Nanyang Technological University) for offering the research funding and scholarship for his study. Thirdly, he also likes to the technicians from the University (especially Mr. Eric Yap, Mr. Nelson and Mr. Seow) for assisting him on this research project. The candidate also appreciate his lab mate and "blunch kaki" (Ji xiaona, Jerry Xiang,

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Applications of Eddy Resolving Methods

Tucker

2014

Unsteady Computational Fluid Dynamics in Aeronautics

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Modeling of Pitching and Plunging Airfoils at Reynolds Number between 1x10^4 and 6x10^4

Cited by 15 publications

References 44 publications

Unsteady force generation and vortex dynamics of pitching and plunging aerofoils

Unsteady force generation and vortex dynamics of pitching and plunging aerofoils

Experimental and computational study of flapping wing aerodynamics at low reynolds number

Applications of Eddy Resolving Methods

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