An optimization approach to vibration reduction in helicopter rotors with multiple active trailing edge flaps

Abstract

The use of multiple active trailing edge flaps for vibration reduction in a helicopter rotor is investigated using an optimization approach. The strong aeroelastic interaction between the unsteady aerodynamic environment and rotating blades are modeled using a comprehensive aeroelastic analysis for helicopter rotors. Pareto optimal points are investigated for tradeoff studies between vibration reduction and control deflections for one, two and four active trailing edge flaps. Numerical results using gradient-based optimization techniques show that four active trailing edge flaps placed at the blade tip and actuated at higher harmonics of the rotation speed yield a vibration reduction of about 72 percent in forward flight when vibration alone is minimized. Such flaps can be actuated by smart materials. It is shown that using upto four trailing edge flaps at the blade tip (outer 20%) is optimal for reducing vibration with reasonably low control angle deflections and therefore low power requirements. It is possible to achieve significant reductions in control deflections by settling for somewhat lower vibration reductions.