Researchers envision a “muffler” for aircraft engines

A team of researchers describes the development of a new porous graphene-based material that can significantly reduce the noise of aircraft engines. Their work has been published in Nature Scientific Reports.

The development of innovative porous absorbers has attracted a lot of interest in recent decades due to their sound absorption capacity, especially in the technical field. However, these materials are generally bulky and heavy, which limits their applications. In a recent study, researchers at the Materials and Structures Center (MAST), University of Bath, may have achieved a breakthrough in reducing aircraft noise by coming up with a new ultralight material.

Noise reduced to “that of a hair dryer”

This material is a graphene oxide/polyvinyl alcohol airgel. The latter is a polymer most often found in glue or paint. To give it soundproofing properties, the researchers embedded this airgel in a honeycomb scaffolding structure. The porous structure allows: dissipate sound through energy transfer from sound to thermal energy when the incoming waves collide with the porous walls.

In tests, the airgel would have managed to reduce ambient noise by approximately 15.8 decibelswhich would reduce the noise of a jet engine (to 140 decibels on take-off) to ” that of a hair dryerthe researchers said.

aircraft with graphene engine
Michele Meo presents his airgel. Credits: University of Bath

An ultra-light material

The use of graphene, an extremely light material, has eliminated the weight limitation. As it is, this airgel weighs only 2.1 kg per cubic metermaking it the lightest soundproofing ever made.

« We have successfully produced extremely low density using a liquid combination of graphene oxide and a polymer, which are formed with whipped and freeze-dried air bubblesunderlines Michele Meo, lead author of the study. ” At a very basic level, the technique can be compared to whipping egg whites to make meringues: it is firm, but there is a lot of air in it, so there is no loss of weight or efficiency to achieve major improvements in terms of comfort and sound« .

For the researchers, this material could be applied in different ways, “initially in aerospace for aircraft engines, but possibly also in many other areas such as automotive and maritime transport, as well as building and constructionMichele Meo continues.

The latter thought that this new material could be used within a year and a half. That said, it will likely take more time to ensure that this new “muffler” can be durable and flame retardant enough for aerospace use.