A flight demonstration for airframe noise reduction technology

This article overviews activities and results for an initial flight demonstration of a project, FQUROH, to develop and mature airframe noise reduction technologies. The project aims to demonstrate technologies for reducing airframe noise through three flight tests using aircraft with modified high-lift devices and landing gear. It intends to verify the design methods that utilize advanced computational fluid dynamics (CFD) and the feasibility of practical noise reduction concepts. The main purposes of the initial demonstration using a JAXA’s research aircraft in 2016 were to establish the processes for flight testing, including modification of the aircraft and experimental procedures, as well as to evaluate preliminary noise reduction designs. In the design process, noise reduction concepts for the flap and main landing gear were successfully applied to the actual complex geometries of the aircraft using advanced CFD, and the noise reduction effects were confirmed with noise measurements in wind tunnel tests. Based on the designs, the flap and main landing gear modifications were manufactured and installed on the aircraft. The flight demonstration campaign was successfully carried out with 177 noise source measurements, and encouraging results were obtained that show the feasibility of the noise reduction design method.