Measurements of Lift Fluctuations Due to Turbulence

Citation

Lamson, Philip (1956) Measurements of Lift Fluctuations Due to Turbulence. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2ZDV-9T79. https://resolver.caltech.edu/CaltechETD:etd-03262004-115115

Abstract

The fluctuating lift of a rigid wing in turbulent flow is studied. The power spectra of the lift and of the turbulent fluctuations are measured. From these measurements the aerodynamic admittance of the wing is obtained. The ratio of span/scale of turbulence is varied by means of movable end plates. For a distance between the end plates of the order of the scale of turbulence the aerodynamic admittance is expected to approach the computed values of Sears. This is shown to be the case if the reduced frequencies are larger than k = 0.8. For smaller k the experimental admittance falls below Sears' values. For large ratios of span/scale of turbulence the aerodynamic admittance is decreased for all frequencies and becomes nearly independent of frequency in the investigated range 0.2 <= k <= 2. In general the measurements support the simplifying assumptions made in the statistical approach to gust loads and buffeting initiated by Clementson and by Liepmann.

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