The influence of reacting gases on the motion of collapsing cavities

Abstract

An analysis was performed on a collapsing cavity containing reacting gases. It was determined that with reacting gases in the cavity there was significant departure from the fluid mechanics of collapse of a cavity containing inert gases. When reacting gases are present, the nonlinear differential equations of motion, energy, and kinetics must be solved simultaneously. It was found that the time required to reach a given radius during collapse was greater for an exothermic reaction occurring in the gas phase than for the cavity containing a nonreacting gas. For the exothermic reaction the collapse time increases with increasing magnitude of the heat of reaction, while for an endothermic reaction the collapse time does not increase indefinitely with increasing heat of reaction but instead decreases and approaches a finite limit. For small heats of reaction the influence of a reacting gas on cavity motion is only readily detectable during the rebound of the cavity. When the collapse time approaches the half period of the wave, the conversion increases with acoustic pressure. However, when the collapse time approaches the period of the wave, the conversion first decreases, then increases with increasing acoustic pressure. Additional description are presented in the text delineating the behavior of the cavity during the collapse when a gas is reacting within the cavity.