Effects of pressure impulse and peak pressure of a shockwave on microjet velocity in a microchannel

We experimentally investigate the effect of a shockwave on the velocity of a microjet and underwater cavitation onset in a microchannel, focusing on the pressure impulse and peak pressure of the shockwave. The pressure impulse and peak pressure of the shockwave are separately varied by using non-spherical laser-induced shockwaves (Tagawa et al. in J Fluid Mech 808:5–18, 2016). We conduct two kinds of experiments. In one experiment, we install a narrow tube and a hydrophone in different configurations in large water-filled tank. We measure the shockwave pressure and the jet velocity simultaneously in order to elucidate the effects of pressure profile of shockwaves on the jet velocity. In the other experiment, we record the jet formation and cavitation onset to investigate the effect of cavitation onset on the jet velocity in an L-shaped microchannel. The experimental results suggest that the jet velocity depends only on the pressure impulse of the shockwave, while the probability of cavitation onset depends only on the peak pressure of the shockwave. The above findings provide new insights for advancing a control method for high-speed microjets.