Variable Geometry Chevrons for Jet Noise Reduction

Abstract

Boeing is applying cutting edge smart material actuators to the next generation morphing technologies for aircraft. This effort has led to the Variable Geometry Chevrons (VGC), which utilize compact, light weight, and robust shape memory alloy (SMA) actuators. These actuators morph the shape of chevrons on a jet engine fan nozzle trailing edge in order to optimize acoustic and performance objectives at multiple flight conditions. We have completed a flight test of the VGC system on a Boeing 777-300ER with GE-115B engines. In this paper we describe the VGC design, development and performance during flight test. We demonstrated autonomous operation of the VGCs, which did not require a control system or aircraft power. The VGC concept demonstrated an exciting capability to optimize jet nozzle performance at multiple flight conditions. The VGC system provided a robust test vehicle to explore chevron configurations for community and shock-cell noise reduction. This capability was demonstrated with two examples of a parametric study which showed the influence of VGC configurations on community noise reduction and shock-cell generated cabin noise reduction during cruise.