Visualization of the flow morphology of submerged jets in subcritical and supercritical water

Abstract

Direct observation of flow behaviors is helpful for design of supercritical water reactor, so an in situ observation platform was built. Water jets under sub- and supercritical conditions (300–550 °C, 23 MPa) were observed by high-speed camera, which can be divided into four typical morphologies: mushroom momentum jets, amorphous plumes, banded plumes and cylindrical momentum jets. The time-average velocity field of each morphology was obtained through the image correlation method to quantitatively describe the flow and diffusion characteristics of jets. The influencing factors on the jet morphology, including the initial flow state of the jet, the driving force of the jet and the turbulence intensity of the ambient fluid, are analysed. Several dimensionless quantities are introduced to describe these factors quantitatively. The results show that the driving force of the jet is the decisive factor to appear to be a plume or momentum jet. The jet initial state has a large influence on the formation of the mushroom vortex. Turbulence of ambient fluid can lead to irregular deformation of the jet shape.