As part of its Advanced Air Transport Technology (AATT) Project, NASA is working on a new leading-edge wing design that aims to decrease aircraft noise while taking off and landing.
When someone mentions noise pollution by aircraft, often the first thing that comes to mind is the roar and whine of the jet engines that propel the vehicle through the sky, but the airframe and especially the wings can produce a lot of noise as well. This is due to the mind-bogglingly complex flow of air over the lifting and control surfaces, and is loudest when an aircraft is flying slowly through the denser air at low altitude.
Such noise is a problem on several levels. It's not only unpleasant and disruptive for people living in the vicinity, but it wastes energy that could be used to propel the craft. It's also expensive, because airports base their fees in part on the amount of noise an aircraft generates.
To better understand this phenomenon and find ways to mitigate it, NASA engineers completed subsonic wind tunnel testing in January 2021 on a one-tenth scale model of a new wing design called the Quiet-High-Lift version of the Common Research Model (CRM-QHL).
The test model consisted of a simplified fuselage cut in half and laid on its flat side on the floor of the wind tunnel. On the fuselage is mounted a detailed model of an aircraft wing, including operating slats and flaps, as well as a model engine and a retractable undercarriage. This allows the researchers to gather empirical data with which to assess the extremely complex computer models needed to simulate wing noise.
The idea is to modify wing components like the leading-edge slat and trailing-edge flaps to make them more efficient in terms of their aerodynamic, structural, and acoustic performance using shape-memory alloys. When the small-scale model tests are completed, the plan is to pass on to large-scale wind tunnel tests to develop the technology to the point where it can be adopted by the aerospace industry.
Source: NASA
