Modeling Transverse Gusts Using Pitching, Plunging, and Surging Airfoil Motions

Abstract

Three model-motions were developed to replicate the aerodynamic response of a transverse gust. These motions included a pure-plunging and two three degree-of-freedom motions that approximated the angle-of-attack distribution produced by the gust. Using inviscid models and viscous flow simulations, the response of the gust and model-motions were compared as a function of the non-dimensional reduced frequency. The inviscid model was found to overestimate the influence of the rotational added-mass in the three degree-of-freedom motions. In contrast, the viscous flow simulations showed that the two primary sources of discrepancy between the gust and model-motions lie in the non-linear angle-of-attack distribution caused

Three-Dimensional Effects on Plunging Airfoils at Low Reynolds Numbers

“…For instance, authors have reported numerical and experimental results for periodic longitudinal gusts [4,5], transient localized transverse gusts [6], transient plunge maneuvers [7][8][9] and for vortical gusts [10,11], where the gust is induced by a passing vortex over the airfoil. The latter differs with respect to the others in that the gust intensity (i.e.…”

“…The similitude between transverse localized gusts and plunge/pitch maneuvers was also explored by Leung et al [9], using 2D simulations. They considered a Re = 1000 and gust ratios G = V/U ∞ = 0.27 and 0.57, for different durations of the gust.…”

“…In the present work we consider Direct Numerical Simulations (DNS) of large-amplitude plunging maneuvers, similar to the experiments of Perrotta and Jones [8], but at somewhat higher Reynolds number and velocity ratios than in Leung et al [9]. In particular, we intend to characterize the influence of the Reynolds number on the aerodynamic forces by performing simulations at Re = 1000 and 5000.…”

Characterization of Aerodynamic Forces on Wings in Plunge Maneuvers

“…The flow perturbations in unsteady environments are highly variable, so researchers often consider canonical configurations to characterize the different contributions to the aerodynamic response of the wing. One recent example of the use of canonical configurations is the work of Leung et al [4] who modelled transverse gusts using different airfoil motions: pitching, plunging and surging. Another example is the work of Mulleners et al [5] as well as Granlund et al.…”

Improved approximations to the Wagner function using sparse identification of nonlinear dynamics

“…The shed vorticity is subsequently assumed to convect with the freestream velocity, and does not dissipate or translate in a direction transverse to the flow. While these assumptions required for application of classical unsteady aerodynamic theory are quite strong, it continues to be successfully applied across a range of applications, such as in the modeling and regulation of lift during gust encounters [31,24,49,3], and for estimating the circulation of vortices produced by vertical gust generators [23]. At the core of classical unsteady aerodynamic theory are a small number of related functions that describe the response of the flow, and particularly the lift and moment on the airfoil, to unsteady conditions.…”