How to spray? Ask the bombardier beetle

April 2nd, 2008 - 11:31 am ICT by admin  

London, April 2 (IANS) The bombardier beetle fires a powerful jet of hot, toxic fluid to fend off predators. This has now inspired designers to improve spray technologies, according to a study. The new beetle-inspired technology will interest firms making drug-delivery systems such as inhalers, or engineers seeking a more energy-efficient mechanism for fuel injection in car engines.

While the chemical reaction behind the bombardier’s venom has been long known, the power behind the squirt, up to eight inches, has remained a mystery.

Researchers from Britain and Sweden now believe they have the answer.

Different gases build up in the beetle’s abdomen but mix together in a connected “combustion chamber” to produce a toxic element. This hot fluid is then fired at predators like frogs and birds.

The key to the beetle’s powerful defensive trick is in its combustion chamber’s entry and exit valves.

As the gases react together, they generate heat and increase the pressure in the closed chamber. When it reaches a critical point, the end of the exit valve is forced open and the hot fluid is ejected as a powerful burst of toxic steam in a process known as “flash evaporation”.

Once the gas is released, the exit valve closes, the inlet valve opens and the chamber fills again, preparing for the next venomous ejection.

The research team has managed to replicate this process. In a series of experiments using water, the team have been able to fire pulses of hot spray for up to 4 metres and have been able to control the size of the droplets in the spray.

The technique has now been licensed for industrial applications.

Findings of the study have been published in the latest issue of the journal Physics World.

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