Calculated and Measured Blade Structural Response on a Full‐Scale Rotor
Abstract:The restricted problem of the calculation of the bending moment response of a full‐scale rotor to measured airloads is studied here. Data are used from tests of an articulated rotor in flight and in a wind tunnel. Linear equations are used to represent the blade mass and structure, and the solution is obtained by numerically solving the resulting two‐point boundary value problem. The measured aerodynamic loads include effects caused by both rigid blade motion and elastic deformation, and hence, represent an exact aerodynamic model. By comparing the calculated blade bending and torsional moment response with measurement, it is possible to assess the adequacy of the structural model far the calculation of vibratory loads. These comparisons are good for the flap‐ and torsional‐moments at the lower harmonics. The calculations for the chord bending moments are not satisfactory and reveal possible problems with the method of deriving the chord airloads from the measured normal forces, or the representation of the nonlinear lead‐lag damper. The good agreement that is seen for the flap‐ and torsional‐moments represents a case of self‐validation, as the differential‐pressure and strain‐gage measurements are independent sets of measurements.
Document Type: Research Article
Affiliations: Ministe`re de la De´fense, STPA, De´partement He´licopte`res, Paris France
Publication date: January 1, 1988
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