Noise reduction of helicopter rotor blades by using spoiler

Abstract

Noise has always been a major disturbance for every living creature. Noise pollution is, thus, a threat to environmental pollution too. The noise created by a helicopter draws a great contribution to the noise pollution. Reducing the noise that creates from helicopter rotor blades, tail rotors, engine etc. is a one step closer to this crisis. Helicopter noise reduction is a topic of research into designing helicopters which can be operated more quietly. The major source of the noise come from the rotor blade vortex interaction. By attaching spoiler in the helicopter main rotor blades and tail rotors reduce the noise and silence the operation. The spoiler is made of supple, resilient, and durable non-ferrous material, such as rubber, a rubber like material, plastic, rubber-impregnated with thin steel mesh, canvas reinforced rubber, rubber composites, and other durable materials that do not prematurely fatigue. The spoiler attached at the trailing edges of blades have free edges exhibits a non-repeating pattern of feather-like projections that collectively break up the vortex formed by blade rotation by providing clean air for each successive blade. The blade efficiency is also increased by using spoiler. This paper addresses the use of spoiler and comparison of noise level of rotor blades with or without spoiler.