Droplets behaviors of flashing jet in accidental release of superheated liquid. (November 2020) - Zhu, Yucheng
Abstract: Structural failure of an industrial superheated liquid tank or pipe usually results in the flashing jet consisting of a mixture of massive droplets and vapor due to the violent phase transition. In this work, experiments on small-scale releases were carried out with a 20 L storage tank to investigate the droplets behaviors of flashing jets after accidental releases of superheated liquid. Distribution of droplets axial, radial and vertical velocities, as well as droplets diameter along the centreline of flashing jet, were acquired employing a Phase Doppler Anemometry (PDA). The influence of storage pressure, superheat, and nozzle diameter was also studied. Results show that the distribution of actual droplets with different velocities and diameters follows the normal distribution. Droplets mean three-dimensional velocities on the central axis of flashing jet decrease exponentially with the increase of axial distance. The droplets mean diameter first decreases exponentially and finally keeps sable at about 10 μm. Among three-dimensional velocities, the axial velocity is the highest and the vertical velocity is the lowest. Droplets mean three-dimensional velocities increase with the increase of storage pressure, superheat, and nozzle diameter. The droplets mean diameter decreases with the increase of superheat and nozzle diameter but increases with the increase of storage pressure. Highlights: Droplets behaviors of flashing jet were studied using a 3D Phase Doppler Anemometry. Distribution of actual droplets velocities and diameter showed Gaussian shape. Droplets three-dimensional velocities and diameter decrease exponentially on the centreline. Droplets diameter achieved a uniform distribution at the far region. Effects of storage pressure, superheat and nozzle diameter were involved.