Dynamics of a liquid plug in a capillary duct powered by vapor explosion

A theoretical model of liquid plug dynamics powered by vapor explosion in a capillary duct has been proposed in order to provide guidance for designing a fluid propulsion device. The model can evaluate performance parameters such as the amount of useful work, efficiency of energy conversion, generated vapor volume and displacement volume rate of liquid. For example, the efficiency of energy conversion for water under atmospheric pressure and room temperature is calculated at 2.8%. The prediction of the vapor volume agrees well with existing experimental result. The prediction of the displacement volume rate also agrees well with the experimental result and suggests the existence of optimum heat flux at which the displacement volume rate is maximum.