Flow-induced vibrations of low aspect ratio rectangular membrane wings

Rojratsirikul, Pinunta; Genç, Mustafa Serdar; Wang, Zhijin; Gursul, Ismet

doi:10.1016/j.jfluidstructs.2011.06.007

Cited by 114 publications

(102 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 8 shows the variation in maximum membrane mean deformation z max /c and fluctu- (Figure 8). This result compares well within previous findings of a wing of similar aeroelastic properties (Rojratsirikul et al, 2011). At these free-flight conditions, the maximum camber deflection is shown to peak with α = 25 • at the same angle-of-attack found for maximum lifting capability (see Figure 4b).…”

Section: Statisticssupporting

confidence: 91%

“…The DIC-technique is widely used in experimental mechanics, allowing sub-pixel accuracy due to grey value interpolation schemes over the interrogation grid (Schreier et al, 2000). The results agree with previous studies, applying DIC on membrane wings (Rojratsirikul et al, 2011;Galvao et al, 2006;Stanford et al, 2014).…”

Section: Deformation Measurementsupporting

confidence: 89%

“…The most dominant mode again has two chordwise nodes, representative for a flow in near-stall conditions (Rojratsirikul et al, 2011). The spanwise modes carry very little energy (≤ 1% to the total vibration energy in the membrane).…”

Section: Decomposition Of Membrane Dynamicsmentioning

confidence: 99%

See 2 more Smart Citations

Aeromechanics of membrane and rigid wings in and out of ground-effect at moderate Reynolds numbers

Bleischwitz

Kat

Ganapathisubramani

2016

Journal of Fluids and Structures

View full text Add to dashboard Cite

Wind tunnel experiments are conducted using membrane wings and rigid flat-plates in ground-effect at a moderate Reynolds number of Re = 56,000 with ground clearances from 1% to 200% chord length measured from their trailing-edge. A six-axis load-cell captures time-resolved forces and moment while time-resolved stereo digital image correlation (DIC) measurements are performed to capture membrane motions. The lift and drag coefficients of the rigid wing in ground-effect follow well-established trends while the membrane wing appears to exhibit improved coefficients and efficiency (compared to the rigid wing) when in ground-effect. Proper orthogonal decomposition (POD) is applied to study the spatiotemporal structure of membrane vibrations. With increasing angles-ofattack and/or decreasing heights above ground, mode shapes of membrane deformation are dominated by large-scale fluctuations that have a smaller number of local extrema along the chord. Ground-effect induces modifications to the membrane deformation, which appear to be similar to the modifications induced by increasing angles-of-attack in free-flight. At high angles-of-attack in free-flight or at moderate angles in ground-effect, two POD modes of membrane fluctuations are found to be sufficient to capture 90% of all membrane deformations. Under these conditions, a membrane deformation with maximum camber near the trailing edge of the membrane wing is found to correlate with high lift, low drag and a nose down pitching moment. The extrema in membrane deformations and lift and drag forces occur simultaneously, while there is a time-lag between the deformation and the pitching moment.

show abstract

Section: Statisticssupporting

confidence: 91%

Section: Deformation Measurementsupporting

confidence: 89%

See 1 more Smart Citation

Aeromechanics of membrane and rigid wings in and out of ground-effect at moderate Reynolds numbers

Bleischwitz

Kat

Ganapathisubramani

2016

Journal of Fluids and Structures

View full text Add to dashboard Cite

show abstract

“…In the past time and nowadays, aerodynamic researches concentrated on low Reynolds number aerodynamics, transition and laminar separation bubble for efficiency of wind power or flight regime [1][2][3][4][5][6][7][8][9]. As it was mentioned, these flight regime or efficiency of wind power can be improved before the analysis and design of aerofoil operating in the low Reynolds number.…”

Section: Qwurgxfwlrqmentioning

confidence: 99%

Flow characteristics over NACA4412 airfoil at low Reynolds number

Genç

Koca

Açıkel

et al. 2016

EPJ Web of Conferences

View full text Add to dashboard Cite

$EVWUDFW In this study, the flow phenomena over NACA4412 were experimentally observed at various angle of attack and Reynolds number of 25000, 50000 and 75000, respectively. NACA4412 airfoil was manufactured at 3D printer and each tips of the wing were closed by using plexiglas to obtain two-dimensional airfoil. The experiments were conducted at low speed wind tunnel. The force measurement and hot-wire experiments were conducted to obtain data so that the flow phenomenon at the both top and bottom of the airfoil such as the flow separation and vortex shedding were observed. Also, smoke-wire experiment was carried out to visualize the surface flow pattern. After obtaining graphics from both force measurement experiment and hot-wire experiment compared with smoke wire experiment, it was noticed that there is a good coherence among the experiments. It was concluded that as Re number increased, the stall angle increased. And the separation bubble moved towards leading edge over the airfoil as the angle of attack increased.

show abstract

“…The aerodynamic of low aspect-ratio wings have been extensively investigated by aerodynamic researches keen on low aspect ratio wings and low Reynolds numbers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Viscous effects, separated and vortical flows are more prevalent and separation bubbles, transition, and reattachment processes are very attractive and also little understood at low Re number aerodynamics [1].…”

Section: Introductionmentioning

confidence: 99%

Effect of tip vortices on flow over NACA4412 aerofoil with different aspect ratios

Genç

Özkan

Açıkel

et al. 2016

EPJ Web of Conferences

View full text Add to dashboard Cite

Abstract. Effect of tip vortices on flow and laminar separation bubble over NACA4412 aerofoil at low Reynolds numbers and different angles of attack was investigated in detail by performing force and flow visualization via smoke wire technique. Experiments have been done at Reynolds number of 50000 and the wing model of aspect-ratio was 1 and 3, respectively. From the experimental results, the flow visualization results showed that tip vortices effect on the laminar separation bubble and the bubble reduces over the wing with low aspect ratio as the angle of attack increased. Moreover, it was noticed that stall angles decreased as aspect-ratio increased at the same Reynolds number.

show abstract

Flow-induced vibrations of low aspect ratio rectangular membrane wings

Cited by 114 publications

References 34 publications

Aeromechanics of membrane and rigid wings in and out of ground-effect at moderate Reynolds numbers

Aeromechanics of membrane and rigid wings in and out of ground-effect at moderate Reynolds numbers

Flow characteristics over NACA4412 airfoil at low Reynolds number

Effect of tip vortices on flow over NACA4412 aerofoil with different aspect ratios

Contact Info

Product

Resources

About