Simple blast fences called baffles could deliver improvements in air quality for people living near airports, new research has found. Placed behind a runway, the baffles could serve as a “virtual chimney,” funneling emissions from aircraft engines upwards where they can disperse more effectively, thereby reducing the environmental impact on people living nearby.
Prototype baffles have been tested by a team of researchers from Manchester Metropolitan University, Cranfield University, the University of Southampton and the University of Cambridge, with funding from the Engineering and Physical Sciences Research Council (EPSRC).
After preliminary wind tunnel testing of various baffle shapes carried out by Cranfield University, an array of three rows of baffles was tested using laser scanning and chemical sensor techniques. This demonstrated that the aircraft exhaust plume could be made to leave the ground within the airport’s boundary fence, using prototype baffles of less than a man’s height and constructed out of low-cost agricultural windbreak netting on lightweight frames.
The aim of the trial was essentially to test the baffles’ aerodynamics. As the prototype installation was temporary, it was constructed very differently from how a permanent installation might be made. Each baffle must be sufficiently robust to withstand the 80-90 knot blast from a jet engine, but flimsy enough to collapse harmlessly if an aircraft were to hit it. In the trial, this was achieved by restricting the prototype baffle widths to about two meters, but it would be feasible to make them much narrower in a permanent installation. For full-scale use an area of baffles in the order of a thousand square meters would need to be erected behind a runway.
The tests also showed that the baffles dampened engine noise downstream by a modest amount and were helpful in reducing jet blast on the airport perimeter.