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A Dynamic Model Investigation of the Effect of a Sharp-Edge Vertical Gust on Blade Periodic Flapping Angles and Bending Moments of a Two-Blade RotorA two-blade rotor having a diameter of 4 feet and a solidity of 0.037 was subjected to sharp-edge vertical gusts while being operated at various forward speeds to study the effect of the gusts on the blade periodic bending moments and flapping angles. Variables studied included gust velocity, collective pitch angle, flapping hinge offset, and tip-speed ratio. Dimensionless coefficients are derived for the periodic components of the incremental changes in blade flapping angles and bending moments which arise when a rotor blade penetrates a sharp-edge gust. Mental changes in both the flapping angles and bending moments are essentially proportional to gust velocity, and the coefficients express the ratio of these increments to gust velccity. The results show that the flapping coefficient usually increases with an increase in collective pitch angle, is generally dependent on tip-speed ratio, and is essentially independent of the amount of flapping hinge offset. The bending-moment coefficient is also dependent on collective pitch angle and tip-speed ratio. Expected reductions in bending moments are realized by the use of flapping hinges, and further reductions in bending moments are achieved as the amount of flapping hinge offset is increased. Comparison of the experimental results of this investigation with limited available theoretical results shows substantial agreement but indicates that the assumption that the response of the rotor to a sharp-edge gust is independent of the collective pitch angle prior to gust entry is probably inadequate.
Document ID
19890068516
Acquisition Source
Langley Research Center
Document Type
Other - NASA Technical Note (TN)
Authors
McCarty, John Locke (NASA Langley Research Center Hampton, VA, United States)
Brooks, George W. (NASA Langley Research Center Hampton, VA, United States)
Maglieri, Domenic J. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 14, 2013
Publication Date
September 1, 1959
Subject Category
Aerodynamics
Report/Patent Number
NASA-TN-D-31
Accession Number
89N70889
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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