An aircraft has at least one, or as many as eight engines, which provide the thrust needed to fly. There are many different makes and models on aircraft today but all perform the same basic function of taking the air that’s in front of the aircraft, accelerating it and pushing out behind the aircraft. Jet powered aircraft perform this function by compressing the air using turbines, while propeller-powered aircraft use a propeller mounted to the engine. In general, the propeller works like a big screw, pulling the aircraft engine forward while pushing the air behind it
Chevrons guide the air flow at the turbine outlet, influencing efficiency and noise. Due to densely populated airport neighbourhoods and an increasing traffic, noise reduction systems are of high interest. Adaptive chevrons help to reduce engine noise on demand during ground level flight manoeuvres, while the efficiency of the engine especially during cruise can be maximised. State of the art chevrons are thin metal extensions of the turbine housing. The design space is very limited. For the development of active chevron prototypes, three shape memory alloy bending actuators per chevron can be mechanically integrated in order to reduce the section of the engine outlet on demand