The Journal of Supercritical Fluids ( IF 3.9 ) Pub Date : 2021-07-09 , DOI: 10.1016/j.supflu.2021.105346 Yifei Ren 1 , Xiangjin Meng 1 , Zhenqun Wu 1 , Guobiao Ou 1 , Hui Jin 1 , Zhiwei Ge 1 , Qiang Xu 1 , Liejin Guo 1
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.
中文翻译:
亚临界和超临界水中浸没射流的流动形态的可视化
流动行为的直接观测有助于超临界水反应堆的设计,因此搭建了原位观测平台。高速相机观测到亚临界和超临界条件下(300-550 °C,23 MPa)的水射流,可分为四种典型形态:蘑菇动量射流、无定形羽流、带状羽流和圆柱形动量射流。通过图像相关法得到各形态的时均速度场,定量描述射流的流动和扩散特性。分析了射流初始流动状态、射流驱动力和周围流体湍流强度等影响射流形态的因素。引入了几个无量纲量来定量描述这些因素。结果表明,射流的驱动力是出现羽流或动量射流的决定性因素。射流初始状态对蘑菇涡的形成有很大影响。周围流体的湍流会导致射流形状的不规则变形。