System noise assessment of a tube-and-wing aircraft with geared turbofan engines

Abstract

A geared turbofan of increased bypass ratio promises reduced engine noise generation if compared to onventional turbofan engines with lower bypass ratios. As a result, the dominance of other noise sources on-board of an aircraft with geared turbofan engines are emphasized and will become more relevant. Consequently, to get an understanding of the modified noise source ranking due to the new engine concept, a noise assessment of the overall aircraft noise as received on the ground is essential, i.e., a so called system noise assessment. For this study a DLR & TU Braunschweig aircraft design synthesis process with integrated noise prediction capabilities is applied. The noise assessment is not limited to the overall vehicle noise as received on the ground but moreover the dominance and ranking of all individual noise sources is discussed. A direct comparison and evaluation of the flight performance and the system noise of the different vehicle variants under consideration is presented. Finally, the geared turbofan engine is also installed on board of an earlier low-noise aircraft concept featuring engine noise shielding. The influence of low-noise airframe measures in combination with a geared turbofan concept are promising, especially on an airframe architecture dedicated to engine noise shielding.