Launching phenomenon of a centimeter-scale solid object using explosive boiling due to electrical discharge in water

Abstract

Technology to launch objects into the air is essential for various applications. In this study, we propose a solid object launcher that pushes the object of centimeter-scale by the rapid liquid motion resulting from explosive vaporization due to electric discharge in water. In particular, by using the electric discharge in a trapezoid-shaped chamber, we demonstrate that a centimeter-scale L-shaped piece of paper with 0.92 mg mass can be launched with an initial velocity ∼4 m/s in the direction of an elevation angle of ∼50°, while a centimeter-scale paper airplane with 29.6 mg mass can be launched with the maximum velocity ∼2 m/s along a glass slide runway with an elevation angle of ∼45°. In addition, to clarify the mechanism of solid launching phenomena, we systematically carried out vertical launching experiments of the centimeter-scale solid object of 60–340 mg. Moreover, as a central design concept peculiar to the solid launching device, we demonstrate the importance of water-repellent treatment of the solid surface. In the future, our device might be used to provide object-shooting technology for hybrid manufacturing technology or to protect orchards from birds.