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Effect of pretwist on aeroelastic response of a rotor system with dynamic stall and dynamic wake
V. Laxman,
Published in
Volume: 3
Pages: 2197 - 2296
Flight test data of helicopters indicate that vibratory levels in the fuselage exhibit a wide spectrum of frequencies including the dominant blade passage frequency and its integer multiples. The present work attempts to understand the reason for the existence of several frequencies in the response of the fuselage and possible cause for this observed phenomenon by formulating a computational aeroelastic model. In this study, the effect of pretwist on the trim condition and aeroelastic response of a rotor system with dynamic stall and dynamic wake has been analysed. The differential equations of motion are solved in time domain in a sequential manner to obtain the response of all the blades in the rotor system, the inflow variables, and the sectional loads at every time step. The influence of aerodynamic modeling on the trim condition of the rotor blade in forward flight has been brought out. It is found that the aerodynamic model incorporating dynamic wake and dynamic stall effects predict the trim parameters whose variation with forward speed resemble qualitatively similar to those obtained in flight test. It is shown that the structural coupling due to blade pretwist significantly influences the rotor blade response and loads compared to an untwisted rotor blade.
About the journal
Journal34th European Rotorcraft Forum 2008, ERF34