A STUDY ON CRITICAL TWO-PHASE FLOW THROUGH A LABYRINTH

Characteristics of critical two-phase flow through a very narrow rectangular channel and a labyrinth channel have been investigated both experimentally and theoretically. The channel was made of transparent glass plates, to observe the flow pattern and to measure the bubble velocity by an optical method. The critical flow rate was measured for various inlet conditions. For the rectangular channel, the measured flow rate under the subcooled condition of the inlet was larger than theoretical estimations by conventional models, because the thermal nonequilibrium between phases was significant in the experiment. By considering such a nonequilibrium effect, a new model was proposed, and the result was compared with experimental results. For the labyrinth channel, the measured flow rate was smaller than that for the rectangular channel, due to the pressure loss by repeated acceleration. The critical flow rate in the labyrinth channel was also predicted theoretically.