System Noise Assessment of a Tube-and-Wing Aircraft with Geared Turbofan Engines

A geared turbofan with an increased bypass ratio promises reduced engine noise generation if compared to conventional turbofan engines with lower bypass ratios. As a result, the dominance of other noise sources on an aircraft with geared turbofan engines is 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: that is, a so-called system noise assessment. For this study a German Aerospace Center (DLR) and Technical University of Brunswick 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 are discussed. A direct comparison and evaluation of the flight performance and the system noise of the different vehicle variants under consideration are presented. Finally, the geared turbofan engine is also installed on 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.