Pressure-decay and thermodynamic characteristics of subcooled liquid in the tank and their interaction with flashing jets

The accidental releases of superheated liquid from tanks or pipes involve violent phase transformation, which would form two-phase releases and generate catastrophic flashing jets. In this work, the pressure and temperature of superheated liquid inside a 20 L tank with different storage pressures, superheats, and nozzle diameters were measured. The characteristics of flashing jets were characterized by measuring the evolution of droplet diameter and three-dimensional (3D) velocities using the Phase Doppler Anemometry (PDA). Results show that the pressure undergoes three phases during release: first rapid decrease phase, slow decrease phase and second rapid decrease phase. The pressure decreases to a critical pressure at the termination of the first phase, and the liquid reaches a critical saturation state and boils. Abundant vapor generated in the tank due to the boiling compensates for the pressure loss, causing the slow decrease of the pressure at the second phase. The critical saturation state is mainly dependent on superheat. 3D velocities and diameter of droplet in flashing jets are mainly controlled by the pressure. Boiling of the superheated liquid under critical saturation state has a vital influence on the dynamic process of two-phase releases, which accelerates the development of flashing jet.