Estimation of Blade Airloads from Rotor Blade Bending Moments
Abstract
A method is developed to estimate the blade normal airloads by using measured flap bending moments -- that is, the rotor blade is used as a force balance. The blade's rotating, in vacuum modes, are calculated and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated from measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1987
- Accession Number
- ADA185858
Entities
People
- William G. Bousman
Organizations
- National Aeronautics and Space Administration