The unsteady lift of an oscillating airfoil encountering a sinusoidal streamwise gust

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Article numberA22
Journal / PublicationJournal of Fluid Mechanics
Volume908
Online published8 Dec 2020
Publication statusPublished - 10 Feb 2021

Abstract

The unsteady lift of an oscillating airfoil encountering a sinusoidal streamwise gust is experimentally investigated. The sinusoidal streamwise gust is generated by a multiple-fan actively controlled wind tunnel. A two-dimensional airfoil with a NACA0015 profile oscillates in the wind tunnel with a pitch motion frequency of fv = 1 Hz while the sinusoidal streamwise gust has a different oscillating frequency of fβ = 1.7 Hz. The non-dimensional unsteady lift coefficients determined from surface pressure show the same trends as Greenberg's prediction. Through spectral analysis, the sum frequency fsum = fβ + fv and the difference frequency fdiff = |fβ-fv|, proposed by Greenberg, are firstly observed in the experiment. The experimental results are compared with Greenberg's theory in the case of a small amplitude of gust velocity variation σ = 0.2. The results of all cases indicate that the experimental results agree generally well with Greenberg's prediction, while there is a small deviation.

Research Area(s)

  • flow-structure interactions