Low-noise retrofit measures for mid-range transport aircraft: simulation benchmark with flyover noise measurements and assessment along different flight procedures

Abstract

DLR has developed a specific low-noise retrofit add-on to reduce the noise generation on board of a conventional mid-range transportation aircraft, i.e., measures to the airframe and engine exhaust nozzle. Selected measures have been installed onboard of DLR’s flying testbed ATRA and been subject to a dedicated flyover noise campaign. The aircraft in its original configuration and the modified aircraft with the selected low-noise measures have been tested and measured in fly-over campaigns in 2016 and 2019, respectively. Simple initial simulation models have been derived from the results and previous component simulations and windtunnel tests to account for the new reduction measures within DLR’s system noise prediction tool PANAM. This paper presents the developed measures as selected for the flight test campaigns. An overview of the conducted flight tests is provided. The overall noise simulation process including aircraft and engine design, flight simulation, and noise prediction is presented. Simulation results obtained from this process are then compared to the measured levels from the flight campaigns. Estimated simulation uncertainties from PANAM are directly compared to differences between measured and simulated levels. Finally, a parameter study is conducted in order to assess the reduction potential of the novel retrofit measures along different simulated flight procedures. Spacial noise distribution in SEL contours is assessed.