System noise assessment of conceptual tube-and-wing and blended-wing-body aircraft designs

Abstract

Within the DLR’s internal project SIAM, future low-noise aircraft designs for a medium range civil transport aircraft are created. An existing system noise simulation process is further upgraded in order to process aircraft designs and expert input from other DLR expert groups and enable a specified and documented overall assessment. Vehicle concepts from different groups are processed and subject to a comparative assessment in order to judge the acoustic performance of these vehicles against each other. The selected vehicles are evolutionary concepts in the form of low-noise variants of conventional tube-and-wing aircraft and revolutionary blended-wing-body concepts. Specific project goals are defined for this comparative assessment. One project goal is to reduce the total aircraft noise by at least 2 EPNdB at each certification location relative to a current state-of-the-art reference aircraft designed for an entry into service in 2035. In addition, since airframe noise is typically not relevant at the certification locations, an airframe specific noise goal is defined, which requires the airframe noise level during approach to be lower than for the reference aircraft’s. This goal is assessed in the maximum A-weighted SPL metric, because the EPNL metric cannot be evaluated for individual components. In addition to the two project noise goals mentioned above, the SEL contour areas along approach and departure are evaluated, because they determine the overall impact of new vehicles on long-term noise contours when operated in a fleet or assessed within an airport scenario. However, those aspects are not covered within this study, because its focus lies on single event noise. Ultimately, all vehicles are evaluated against the ambitious "Flightpath 2050 goal" for perceived noise level reduction. While it is demonstrated that significant noise reductions can be achieved in certification levels and SEL contour areas, the "Flightpath 2050" goal cannot be achieved at the sideline location. To reach this goal, additional technical measures are required.