System Noise Assessment of SFB880 Vehicle Concepts

Kurzfassung

To fully evaluate the vehicle concepts of the collaborative research center (SFB) 880, it is crucial to include a system noise assessment. Dedicated tools that are suitable for a system noise assessment on a comparative basis within the conceptual aircraft design phase are used. For the selected SFB 880 aircraft, new noise prediction capabilities are required for Coanda flaps, ultra-high bypass ratio engines, and propeller engines. For the Coanda flap, a noise source model does not exist yet. Hence, it is initially estimated with a conventional Fowler flap model. The ultra-high bypass ratio engine is predicted using a well-known parametric source model with a modified underlying database. For the propeller sound, a simplified analytical equation is selected. In addition to the new noise prediction capabilities, individual flightpaths per vehicle are required. These are calculated with a tool that was specifically developed for the use within the conceptual aircraft design phase. The system noise assessment reveals that a significant noise reduction can be achieved through the use of an ultra-high bypass ratio engine. Furthermore, it is shown that propeller driven aircraft lead to increased noise compared to turbofan driven aircraft for departure. Along the simulated approach, however, propeller driven aircraft are quieter than aircraft equipped with turbofan engines. Up to now the noise of the Coanda flap is an estimate, but it is expected that it does not contribute significantly to the overall noise on the ground.