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Performance optimization for rotors in hover and axial flightPerformance optimization for rotors in hover and axial flight is a topic of continuing importance to rotorcraft designers. The aim of this Phase 1 effort has been to demonstrate that a linear optimization algorithm could be coupled to an existing influence coefficient hover performance code. This code, dubbed EHPIC (Evaluation of Hover Performance using Influence Coefficients), uses a quasi-linear wake relaxation to solve for the rotor performance. The coupling was accomplished by expanding of the matrix of linearized influence coefficients in EHPIC to accommodate design variables and deriving new coefficients for linearized equations governing perturbations in power and thrust. These coefficients formed the input to a linear optimization analysis, which used the flow tangency conditions on the blade and in the wake to impose equality constraints on the expanded system of equations; user-specified inequality contraints were also employed to bound the changes in the design. It was found that this locally linearized analysis could be invoked to predict a design change that would produce a reduction in the power required by the rotor at constant thrust. Thus, an efficient search for improved versions of the baseline design can be carried out while retaining the accuracy inherent in a free wake/lifting surface performance analysis.
Document ID
19890011602
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Quackenbush, T. R. (Continuum Dynamics, Inc., Princeton NJ., United States)
Wachspress, D. A. (Continuum Dynamics, Inc., Princeton NJ., United States)
Kaufman, A. E. (Continuum Dynamics, Inc., Princeton NJ., United States)
Bliss, D. B. (Duke Univ. Durham, NC., United States)
Date Acquired
September 5, 2013
Publication Date
April 1, 1989
Subject Category
Aerodynamics
Report/Patent Number
NAS 1.26:177524
NASA-CR-177524
Accession Number
89N20973
Funding Number(s)
PROJECT: RTOP 505-61-51
CONTRACT_GRANT: NAS2-12789
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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