Development and application of a method for predicting rotor free wake positions and resulting rotor blade air loads. Volume 1, Model and results / by S. Gene Sadler.
Rotor wake geometries are predicted by a process similar to the startup of a rotor in a free stream. An array of discrete trailing and shed vortices is generated with vortex strengths corresponding to stepwise radial and azimuthal blade circulations. The array of shed and trailing vortices is limite...
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Link to online resource Search for the full-text version of this title in HathiTrust |
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| Main Author: | |
| Corporate Authors: | , , |
| Format: | Government Document Book |
| Language: | English |
| Published: |
Washington, D.C. : Springfield, Va. :
National Aeronautics and Space Administration ; For sale by the National Technical Information Service [distributor],
1971.
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| Series: | NASA contractor report ;
NASA CR-1911. |
| Subjects: |
| Summary: | Rotor wake geometries are predicted by a process similar to the startup of a rotor in a free stream. An array of discrete trailing and shed vortices is generated with vortex strengths corresponding to stepwise radial and azimuthal blade circulations. The array of shed and trailing vortices is limited to an arbitrary number of azimuthal steps behind each blade. The remainder of the wake model of each blade is an arbitrary number of trailing vortices. Vortex element end points were allowed to be transported by the resultant velocity of the free stream and vortex-induced velocities. Wake geometry, wake flow, and wake-induced velocity influence coefficients are generated by this program for use in the blade loads portion of the calculations. Blade loads computations include the effects of nonuniform inflow due to a free wake, nonlinear airfoil characteristics, and response of flexible blades to the applied loads. Computed wake flows and blade loads are compared with experimentally measured data. Predicted blade loads, response and shears and moments are obtained for a model rotor system having two independent rotors. The effects of advance ratio, vertical separation of rotors, different blade radius ratios, and different azimuthal spacing of the blades of one rotor with respect to the other are investigated. |
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| Item Description: | Cover title. "December 1971." |
| Physical Description: | iii, 121 pages : illustrations ; 27 cm. Also available online from the NASA Technical Reports Server (http://ntrs.nasa.gov/). Address as of 04/05/06: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720007340%5f1972007340.pdf. |
| Bibliography: | Includes bibliographical references (pages 69-70) |