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An unsteady lifting surface method for single rotation propellersThe mathematical formulation of a lifting surface method for evaluating the steady and unsteady loads induced on single rotation propellers by blade vibration and inflow distortion is described. The scheme is based on 3-D linearized compressible aerodynamics and presumes that all disturbances are simple harmonic in time. This approximation leads to a direct linear integral relation between the normal velocity on the blade (which is determined from the blade geometry and motion) and the distribution of pressure difference across the blade. This linear relation is discretized by breaking the blade up into subareas (panels) on which the pressure difference is treated as approximately constant, and constraining the normal velocity at one (control) point on each panel. The piece-wise constant loads can then be determined by Gaussian elimination. The resulting blade loads can be used in performance, stability and forced response predictions for the rotor. Mathematical and numerical aspects of the method are examined. A selection of results obtained from the method is presented. The appendices include various details of the derivation that were felt to be secondary to the main development in Section 1.
Document ID
19900016624
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Williams, Marc H. (Purdue Univ. West Lafayette, IN, United States)
Date Acquired
September 6, 2013
Publication Date
July 1, 1990
Publication Information
Publisher: NASA
Subject Category
Aerodynamics
Report/Patent Number
E-5428
NAS 1.26:4302
NASA-CR-4302
Accession Number
90N25940
Funding Number(s)
CONTRACT_GRANT: NAG3-499
PROJECT: RTOP 505-62-4D
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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