Reduction of Aircraft Noise by Wing Design and Add-On Technologies

Kurzfassung

As aircraft noise is a major concern for residents living in the vicinity of airports, this thesis investigates the noise reduction capability of a large and heavy tube-and-wing airliner through design modifications employing a simulation study. The planform parameters determine the airplane's flight mechanics and, in turn, influence the ground noise impact. The planform is changed in a parameter study, and low noise techniques, namely fan sound shielding, ultra-high bypass ratio engine, droop nose, trailing-edge brush, and landing gear fairing, are sequentially applied to the airplanes. Their ground noise is evaluated based on the DLR's awakening criterion. Absent of low-noise technologies, the approach speed and the ground track length between the point of break release and the point at which the airplane reached a height of 1200 m are found to be the most important criteria to lower the approach and departure-induced ground noise, respectively. Since the departure-induced ground noise causes the majority of the overall awakening reactions, it dominates the selection process of the optimal airplane design. The application of low-noise technologies influences the airplane's flight performance, which shifts the set of the planform parameter values to achieve the optimal airplane design. In summary, it is shown that the collective consideration of various planform parameters while designing airplanes has been found to be more effective than just the sole application of low-noise technologies to existing airplanes.