2140 ヘリカル管内における気液二相流の流動特性  [in Japanese] Flow Characteristics of Gas-Liquid Two-Phase Flow in Helically Coiled Tubes  [in Japanese]

Helical coil type heat exchanger tubes are used in the evaporator and the superheater of the prototype fast-breeder reactor (FBR) Monju. The present study visualizes the flow pattern of gas-liquid two-phase flow in the helical tubes to clarify the influence of centrifugal acceleration due to the curvature. Flow regime maps for two different curvature radii are obtained. The results reveal that the bubbly flow regime expands and stratified flow regime vanishes compared to the straight horizontal pipe flow owing to the centrifugal force acting on the liquid phase. The bubbly flow regime further expands if the curvature radius increases because of slowdown of the internal secondary flow induced by the centrifugal acceleration.