Aeroelastic response of helicopter rotors using a 3D unsteady aerodynamic solver

Abstract

The prediction of blade deflections and vibratory hub loads concerning helicopter main rotors in forward flight is the objective of this work. They are determined by using an aeroelastic model derived through the coupling between a nonlinear blade structural model and a boundary integral equation solver for three-dimensional, unsteady, potential aerodynamics. The Galerkin method is used for the spatial integration, whereas the periodic blade response is determined by a harmonic balance approach. This aeroelastic model yields a unified approach for aeroelastic response and blade pressure prediction that may be used for aeroacoustic purposes, with the possibility of including effects from both blade-vortex interaction and multiple-body aerodynamic interaction. Quasi-steady aerodynamic models with wake-inflow from the three-dimensional aerodynamic solver are also applied, in order to perform a comparative study. Numerical results show the capability of the aeroelastic tool to evaluate blade response and vibratory hub loads for a helicopter main rotor in level flight conditions, and examine the sensitivity of the predictions on the aerodynamics model used.

Investigation on a High-Frequency Controller for Rotor BVI Noise Alleviation

“…(1) is solved by using the harmonic balance approach. 20,22 It is a methodology suitable for the analysis of the asymptotic solution (as time goes to infinity) of differential equations forced by periodic terms, as in the present case. Because of the presence of nonlinear contributions deriving both from structural terms and from the free-wake aerodynamic loads prediction, the final system has to be solved using an iterative approach.…”

Assessment of a comprehensive aeroelastic tool for horizontal‐axis wind turbine rotor analysis

“…Steady‐periodic responses to arbitrary wind conditions (like, for instance, axial wind, yawed wind and vertical shear layer conditions) are evaluated by a harmonic balance approach applied to the proposed solution schemes .…”

“…Steady-periodic responses to arbitrary wind conditions (like, for instance, axial wind, yawed wind and vertical shear layer conditions) are evaluated by a harmonic balance approach applied to the proposed solution schemes. 17,18 Concerning the aeroelastic stability analysis, widely used techniques are based on the evaluation of the time-marching aeroelastic response to perturbations, 31,32 or on the eigenanalysis of the aeroelastic system linearized about a steady-periodic equilibrium condition. 33 The latter is extensively applied in rotorcraft and wind turbines aeroelasticity, 34,35 and is adopted here, as well.…”

Synthesis of a Rotor BVI Noise Active Controller Through an Efficient Aerodynamics/Aeroacoustics Solver

“…(13) is solved by using the harmonic balance approach. 25,27 It is a methodology suitable for the evaluation of the asymptotic solution (as time goes to infinity) of differential equations forced by periodic terms, as in the present case. Due to the presence of nonlinear structural terms and aerodynamic contributions in the resulting equation, the final system has to be solved using an iterative procedure.…”