Effects of kinematics on aerodynamic periodicity for a periodically plunging airfoil

Wu, Jianghao; Wang, Dou; Zhang, Yanlai

doi:10.1007/s00162-015-0366-5

Cited by 4 publications

(1 citation statement)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Before studying the aerodynamic forces and flow field of the wing model, CFD code [14], mesh density, the first mesh spacing, computation time step, and computational domain size used in this study have been validated, as shown in Figure 4, here, the time t is non-dimensionalized by the period of spinning around wing span axis. As a result, a numerical solution independent of mesh and time steps can be achieved when the mesh dimension is 70 × 75 × 152 (in the normal, chordwise, and spanwise directions, respectively), the domain size is 30c, the first mesh spacing at the wall is 0.001c, and 400 time steps are used in one spinning cycle.…”

Section: Mesh Model and Validationmentioning

confidence: 99%

Aerodynamics and Flight Dynamics of Free-Falling Ash Seeds

Fang¹,

Zhang²,

Liu³

2017

WJET

Self Cite

View full text Add to dashboard Cite

Samaras or winged seeds spread themselves by wind. Ash seed, unlike other samaras, has a high aspect ratio wing which can generate enough lift force to slow down descent by rotating about the vertical axis and spinning around its wing span axis simultaneously. This unique kinematics and inherent fluid mechanism are definitely of great interest. Detailed kinematics of free falling ash seeds were measured using high-speed cameras, then corresponding aerodynamic forces and moments were calculated employing computational fluid dynamics. The results show that both rotating and spinning directions are in the same side and the spinning angular velocity is about 6 times of rotating speed. The terminal descending velocity and cone angles are similar to other samaras. Analysis of the forces and moments shows that the lift is enough to balance the weight and the vertical rotation results from a processional motion of total angular moment because the spin-cycle-averaged aerodynamic moment is perpendicular to the total angular moment and can only change its direction but maintain its magnitude, which is very similar to a spinning top in processional motion except that the total angular moment of ash seed is not along the spin axis but almost normal to it. The flow structures show that both leading and trailing edge vortices contribute to lift generation and the spanwise spinning results in an augmentation of the lift, implying that ash seeds with high aspect ratio wing may evolve in a different way in utilizing fluid mechanisms to facilitate dispersal.

show abstract

Section: Mesh Model and Validationmentioning

confidence: 99%