Flow Structures Around an Oscillating-Wing Power Generator

Fenercioglu, Idil; Zaloğlu, Berk; Young, John; Ashraf, Mahmud; Lai, J.C.S.; Platzer, Max F.

doi:10.2514/1.j053950

Cited by 22 publications

(15 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The non-dimensional plunge motion amplitude h is 1.05 and the pitch motion amplitude θ o is 73° as consistent with previous studies [13,14]. The reduced frequency is set constant as k = 0.8 throughout this study.…”

Section: Methodssupporting

confidence: 57%

“…There is a good agreement between experimental results and 2D Navier-Stokes simulations that both show higher efficiency using non-sinusoidal motion. The Navier-Stokes computations [12,13] and experimental studies [14] confirmed the potential superiority of a non-sinusoidal oscillating power generator.…”

Section: Introductionmentioning

confidence: 89%

“…Platzer et al [12] and Ashraf et al [13] numerically investigated the non-sinusoidal motion of a flapping-wing power-generator with reduced frequency of k = 0.8 pitching amplitude of θ = 73° and plunge amplitude of h =1.05 c. Their results showed that around 17% increase in power generation and around 15% increase in efficiency could be achieved as compared with those of sinusoidal motions. Further investigations are performed by Fenercioglu et al [14] experimentally on flapping-wing power-generator using the same motion parameters with Platzer et al [12] and Ashraf et al [13], for a flapping wing with non-sinusoidal pitching and plunging motions about its quarter and mid-chord pivot points with different stroke reversal times of 0.1 (rapid motion) to 0.5 (sinusoidal motion). There is a good agreement between experimental results and 2D Navier-Stokes simulations that both show higher efficiency using non-sinusoidal motion.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of phase angle on tandem flapping-wing power generation

Karakaş

Fenercioglu

2017

Int. J. EQ

Self Cite

View full text Add to dashboard Cite

Two tandem wings undergoing two-dimensional sinusoidal and non-sinusoidal pitch and plunge motions are studied experimentally in a water channel at a chord-based Reynolds number of 10,000. The hindwing operates in the wake of the forewing, and its performance is affected by the vortices shed by the forewing in a tandem wing application. The vortex-wing and vortex-vortex interactions are affected by the changes in the phase angle between the fore and the hind wings. This study investigates how the changes in phase angle between the motions of the two wings play a role on the leading edge vortex (LEV) formations on the hindwing and the resulting effects on the power coefficient and the efficiency. The instantaneous lift and torque are measured by a force sensor; the velocity fields are captured by a digital particle image velocimetry (PIV) system. Sinusoidal and non-sinusoidal oscillations consisting of a pitch leading plunge motion with ϕ = 90° phase angle are used for the fore and hind wing motions. Different phase angles between the fore and hindwings are tested for the tandem configuration in the range of ψ = 0°-360° with an increment of 45°. The pitch pivot point to point distance of two chords was set between the fore and hindwings. It is found that the phase angle between the tandem foils determines the timing and the sign of the forewing-shed LEV when the hindwing encounters this LEV. Such an interaction affects the LEV formation, growth and shedding on the hindwing and results in a change in power generation performance of the hindwing. The results further show that at this specific distance between the wings, the maximum power coefficient and efficiency occur when the phase angle between the motions of the tandem wings is near ψ = 135° for the sinusoidal pitching and plunging.

show abstract

Section: Methodssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of phase angle on tandem flapping-wing power generation

Karakaş

Fenercioglu

2017

Int. J. EQ

Self Cite

View full text Add to dashboard Cite

show abstract

“…Platzer et al (2010) and Ashraf et al (2011) numerically investigated non-sinusoidal motion of an oscillating-wing power generator with different pitch stroke reversal times and achieved up to 17% increase in power generation and up to 15% increase in efficiency for non-sinusoidal flapping compared to those of sinusoidal motions. Increase in both power generation and efficiency were also observed for a flapping foil power generator using the same motion parameters (Fenercioglu et al 2015) and good agreement was found between experimental results and 2D Navier-Stokes simulations. Their results showed the beneficial aspects on efficiency enhancement from non-sinusoidal motion profile.…”

Section: Introductionsupporting

confidence: 59%

Effect of Side-Walls on Flapping-Wing Power-Generation: an Experimental Study

Karakaş

Fenercioglu

2016

JAFM

View full text Add to dashboard Cite

Effect of constrained flow is investigated experimentally for a flapping foil power-generator. The flow structures around and in the near wake of a flat plate placed between two side walls are captured via PIV technique with simultaneous direct force measurements in uniform flow at Re = 10 000. The rectangular flat plate oscillates with periodic non-sinusoidal pitching and plunging motions about its 0.44 chord position with stroke reversal times (TR) of 0.1 (rapid reversal) to 0.5 (sinusoidal reversal), phase angles of  = 90° and 110°, plunge amplitude of 1.05 chords and pitch amplitude of 73° at a constant reduced frequency of k = 0.8. The non-dimensional distances between the side walls and the oscillating flat plate are dw = 0.1, 0.5 and 1.0. Airfoil rotation speed dictates the strength, evolution and timing of shedding of leading and trailing edge vortices; as the stroke reversal time is decreased, earlier shedding of stronger vortices are observed. Increasing the phase angle between the pitching and plunging motions decreases the power generation efficiency for all cases. The highest power extraction coefficient is acquired for the non-sinusoidal case of TR = 0.4 in free flow. Optimum choice of side-wall distance improves power generation of flapping foils compared to free flow performance, up to 6.52% increase in efficiency is observed for the non-sinusoidal case TR = 0.4 with dw = 0.5, with remarkable enhancements for the sinusoidal case; 27.85% increase is observed with dw = 0.5 and 43.50% increase with dw = 1.0 where both cases outperform the highest power generation efficiency of the finite flat plate with non-sinusoidal flapping motion.

show abstract

“…To date, it is still unclear which of the three set-ups provides the best performance [3], but progress made on improving the understanding of the hydrodynamic characteristics of any one of the three set-ups is likely to contribute to progress in 30 the study and application of the other two [4]. The wing oscillation considered in most analyses is harmonic, but it has been shown that performance benefits can also be achieved by considering non-harmonic wing trajectories [5,6]. The remainder of the literature survey in this section and the analyses in this paper focus on the baseline configuration of the oscillating wing, namely that using a 35 fully active kinematic set-up and harmonic wing motion.…”

Section: Introductionmentioning

confidence: 99%

Comparative turbulent three-dimensional Navier–Stokes hydrodynamic analysis and performance assessment of oscillating wings for renewable energy applications

Drofelnik

Campobasso

2016

International Journal of Marine Energy

View full text Add to dashboard Cite

Oscillating wings can extract energy from an oncoming water or air stream, and first large-scale marine demonstrators are being tested. Oscillating wing hydrodynamics is highly unsteady, may feature dynamic stall and leading edge vortex shedding, and is significantly three-dimensional due to finite-wing effects.Understanding the interaction of these phenomena is essential for maximizing power generation efficiency. Much of the knowledge on oscillating wing hydrodynamics stemmed from two-dimensional low-Reynolds number computational fluid dynamics studies and laboratory testing; real installations, however, will feature Reynolds numbers higher than 1 million and unavoidable finite-winginduced losses. This study investigates the impact of flow three-dimensionality on the hydrodynamics and the efficiency of a realistic aspect ratio 10 device in a stream with Reynolds number of 1.5 million. The improvements achievable by using endplates to reduce finite-wing-induced losses are also analyzed. Threedimensional time-dependent Navier-Stokes simulations using the shear stress transport turbulence model and a 30-million-cell grid are performed. Detailed comparative hydrodynamic analyses of the finite and the infinite wings reveal that flow three-dimensionality reduces the power generation efficiency of the * Corresponding author finite wing with sharp tips and that with endplates by about 17 % and 12 % respectively. Presented analyses suggest approaches to further reducing these power losses.

show abstract

Flow Structures Around an Oscillating-Wing Power Generator

Cited by 22 publications

References 27 publications

Effect of phase angle on tandem flapping-wing power generation

Effect of phase angle on tandem flapping-wing power generation

Effect of Side-Walls on Flapping-Wing Power-Generation: an Experimental Study

Comparative turbulent three-dimensional Navier–Stokes hydrodynamic analysis and performance assessment of oscillating wings for renewable energy applications

Contact Info

Product

Resources

About