Experimental research of underwater explosion bubble dynamics between two parallel plates with various distances

In this article, the complex dynamics of underwater explosion bubble between two parallel plates is studied experimentally. The time and length scales of a mini-charge underwater explosion bubble are larger than those of laser-induced bubbles and spark-generated bubbles. The evolution of a bubble with dimensionless distance γ from 0.2 to 0.8 is captured using a high-speed camera in side view. Two different forms of collapse are discussed in detail. The bubble collapses at the center of two plates at a small dimensionless distance γ. With the increase of γ, the bubble splits into two sub-bubbles before collapsing and reverse jets penetrate sub-bubbles. The first pulsation periods of an underwater explosion bubble between two parallel plates are 30% to 50% larger than that of a free field bubble. The dimensionless period decreases on the whole with the increasing γ. The generation of sub-bubbles shortens whole first pulsation period of bubble significantly between γ=0.47 and γ=0.53.