10 years of joint research at DLR and TU Braunschweig toward low-noise aircraft design-what did we achieve?

Abstract

This review article is based on an invited keynote presentation at the 22nd Workshop of the Aeroacoustics Specialists Committee of the CEAS. The event was held in September 2018 in Amsterdam with the main focus on the relation between aircraft design and noise impact. This article reviews the last years of joint research activities between the German Aerospace Center (DLR) and the Technical University of Braunschweig (TU BS) in the field of low-noise aircraft design. The joint research was initiated around 2008 between the DLR Institute of Aerodynamics and Flow Technology and the Institute of Aircraft Design and Lightweight Structures at TU BS. Around that time, DLR was developing a first version of an aircraft noise prediction tool. This tool has then consequently been implemented as a module into the aircraft design synthesis code of the TU BS. In 2012, for the first time, a fully automated and fully parametric aircraft design process with integrated noise prediction capabilities was established, i.e., including a full approach and departure flight simulation. The main focus lies on conventional tube-and-wing aircraft with turbofan or turboprop engine concepts. Ever since 2012, the tools have been under constant development and the simulation chain for low-noise aircraft design has been applied to various aircraft concepts. This article is comprised of a description of the tool development from 2008 until early 2018 and a selected application example. Some lessons learned and a brief outlook on future developments and applications conclude this review.

A Numerical Study on Aircraft Noise Mitigation Using Porous Stator Concepts

“…The nose of the aircraft is aligned with the 180°angle. The directivity plot implies that noise is radiated predominantly towards the upstream and downward directions, the latter of which is attributed to the shielding effect from the wing [50]. For most observer angles, both M800 and M450 configurations produce higher OSPL by 1 to 2 dB relative to the baseline configuration, whereas the M450E configuration produces a reduction of 1 dB.…”

Low-Noise Design of Medium-Range Aircraft for Energy Efficient Aviation

“…More than a decade ago, DLR and TU Braunschweig launched a joint research effort to reduce exterior aircraft noise by assessing promising reduction measures [4]. An automated simulation process for the conceptual design of such low-noise aircraft was established, i.e., see Ref.…”

“…Based on findings from previous studies, simple guidelines for low-noise aircraft design can be deduced and are summarized in Refs. [4,32]. According to these rules, interaction noise sources should be avoided, e.g., jet-flap interaction noise can be avoided by selecting an over-wing engine position.…”

“…Based on a previous DLR report [62] and dedicated low-noise design studies by DLR [4,31], a promising aircraft architecture with an alternative engine option is selected for the mid-range vehicle concepts. A tube-and-wing architecture with the engines mounted above the fuselage-wing junction is most promising for shielding engine noise.…”

“…In the near future, the reduction of community noise will remain a key issue. At this point, DLR Göttingen is contributing to SE 2 A by tackling the noise challenge based on its long-time expertise and available simulation capabilities [4]. Especially since the growth of air transport, noise reduction technologies and their environmental impact are of great importance.…”