If you live near an airport or are a frequent flyer, you may be no stranger to the intense roar of a modern-day aircraft. As the turbines whir into action and force superheated air through the exhaust, sounds as loud as 140 decibels can be heard by nearby onlookers, to the point where noise-reducing earphones are a necessity for visiting airshows to prevent hearing damage.
However, researchers from Bath’s Materials and Structures Centre (MAST) believe they have made a breakthrough in reducing aircraft noise, by creating an ultra-light new material that can reduce aircraft noise by a massive margin. The new material is a graphene oxide/polyvinyl alcohol aerogel (that’s a 2D lattice of ultra-light graphene mixed with a polymer most commonly found in glue) and can absorb huge amounts of sound whilst adding almost no weight at all to the aircraft.
With the addition of the aerogel to passenger jets, it could vastly improve passenger comfort while reducing noise complaints from surrounding areas.
Their research and manufacturing method was published in the journal Nature Scientific Reports.
"This is clearly a very exciting material that could be applied in a number of ways - initially in aerospace but potentially in many other fields such as automotive and marine transport, as well as in building and construction,” said Professor Michele Meo in a statement.
To give it such high noise-insulating properties while keeping weight down, the researchers created a graphene-based aerogel that was then embedded in a honeycomb scaffold structure. The aerogel is porous, which dissipates sound through the energy transfer from sound to thermal energy as the incoming waves collide with the porous walls, causing friction. However, while porous materials are incredibly effective at dissipating sound, they are often far too bulky and heavy to be utilized in performance and aerospace settings. Using a porous aerogel, which is extremely light, allows the researchers to access this incredible ability to reduce noise but vastly reduce the weight of the insulation.
In testing, the aerogel was able to reduce noise by 15.8 decibels, which would reduce the noise of a jet engine to “closer to that of a hair-dryer", according to the researchers.
Not satisfied with creating a more peaceful world, the researchers are now looking to further improve the material so that it may offer heat dissipation as well. They believe it could be in use within 18 months, but that would be subject to rigorous safety testing to ensure it is durable and fire-retardant enough to be used in aerospace.