Southern California may demand new techniques in fire science, but I don't think anyone had explosives in mind when they started their research... Yet, apparently that's exactly what a group in New Mexico is doing: putting out fires by blowing them up.
Bushfires are one of the most deadly and destructive natural disasters in Australia — they can move at incredible speeds and wipe out a town in minutes. Now a team of engineers believe that they can fight these fires by blasting them with explosive force. In this video, you can see how it works.
University of New South Wales engineer Graham Doig is researching how to use explosives in firefighting, and traveled to a New Mexico explosion research facility (yes, there is one) to conduct some experiments.
According to a release from the university about this study:
Doig travelled to the Energetic Materials Research Testing Center — a high-explosives and bomb test site in a remote part of New Mexico — in January this year to scale up tests he originally conducted at UNSW's heat transfer and aerodynamics laboratory.
The New Mexico tests used a four-metre steel blast tube — which contained a cardboard cylinder wrapped in detonation cord — to produce a concentrated shockwave and rush of air. This was directed at a metre-high flame fuelled by a propane burner.
The sudden change in pressure across the shockwave, and then the impulse of the airflow behind it pushed the flame straight off the fuel source. As soon as the flame doesn't have access to fuel anymore, it stops burning.
You might be wondering about something really obvious, which is the fact that the flame is pushed somewhere — and in the bush, that's likely to be more tinder. The answer is that bush fires tend to travel through the tops of brush and trees, leaping from one to the next, fed by the layer of oxygen below. That's one reason why they are so deadly, and can travel so fast.
Once the blast has knocked the fire out of the treetops, it descends to the floor of the forest or brush, where firefighters have a much easier time containing it.