Applying Frequency-Domain Unsteady Lifting-Line Theory to Time-Domain Problems

Bird, Hugh J. A.; Ramesh, Kiran

doi:10.2514/1.j060898

Cited by 1 publication

(1 citation statement)

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“…The SA model is chosen for this problem because of extensive previous experience in applying it successfully for unsteady, separated, and vortex-dominated flows at Re = 10, 000 such as those considered in this research. For instance, this setup has been previously used to study limit-cycle oscillation of a 2-degree-of-freedom aerofoil [47], and leading-edge vortex shedding on finite wings of different aspect ratios [48][49][50][51]. The trip terms in the original SA model are turned off, and for the low Reynolds number cases considered in this research, the effects of the turbulence model are confined to the shed vortical structures and wake.…”

Section: Cfd Setupmentioning

confidence: 99%

Effect of Rounded Trailing Edges on Unsteady Airfoil Loading at Low Reynolds Numbers

Lee,

Ramesh,

Gopalarathnam

2024

Preprint

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The steady potential flow past a traditional airfoil with a round leading edge and a sharp trailing edge can usually be simulated using the assumption of Kutta condition at the trailing edge. However, for the airfoil undergoing unsteady motion, especially at high reduced frequencies, numerical and experimental studies have shown that the flow can curve around the trailing edge, resulting in the stagnation point moving away from the trailing edge. This phenomenon becomes increasingly apparent when the airfoil has a round trailing edge instead of the usual sharp one. In this work, the effect of trailing edge roundness on the unsteady airfoil flow is studied by generating airfoil shapes with various amounts of roundness. Computational fluid dynamics (CFD) studies of unsteady flow past airfoils with different rounded trailing edges are performed to study the effects of the trailing-edge suction force on the flowfield. A composite pressure difference model universally valid on the entire airfoil is derived in this work to take into account the edge radii and the corresponding edge suction effect. We show that, in scenarios where the stagnation point moves away from the trailing edge, a trailing edge suction force associated with the flow curving around the trailing edge is necessary to better estimate the airfoil unsteady load distribution.

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