Studies of swirling annular mist two-phase flow, 1

There is a phenomenon that the rate of heat transfer drops remarkably as dry out occurs in the high dryness region of evaporation tubes in reactor steam generators and forced once-through boilers. By forming helical grooves on the internal surfaces of tubes, the rate of heat transfer is increased against it. In this study, it was attempted to examine the possibility of maintaining liquid film for a long time by adhering liquid drops to a tube wall with a rotary vane inserted in the tube to delay dry out. Accordingly, the basic flow characteristics of annular atomizing flow accompanied by swirling were studied. In vertically downward annular atomizing flow, the torque generated by a rotary vane, the attenuation of torque and swirling angle along channel length, the axial distribution of liquid film flow rate and liquid drop flow rate, the rate of forming liquid drops, the distribution of liquid drop size and pressure loss were clarified. The experimental setup and experimental method are described. The equations representing the torque of flow at the exit of a rotary vane, the change of torque and swirling angle in axial flow and the pressure loss due to a rotary vane were obtained. The efficiency of separating liquid drops with five types of rotary vanes in the core part is shown. (Kako, I.)