Thermo-Hydraulic Instability Due to Blockage of Flow in a Boiling Two-Phase Flow System : 2nd Report, Effects of Flow Channel Conditions

Abstract

The instability caused by stagnant vapor in bends has been investigated experimentally in a boiling, two-phase flow system composed of an N-shaped boiling channel and an adiabatic bypass between an inlet and an outlet plenums. It is found that a complete blockage type and two flow oscillation types whose driving mechanisms are different from each other exist in this instability, and the occurring mechanisms are discussed. The boundaries, where their type instabilities occur, are examined. To clarify the effects of flow channel conditions on this instability, the instability has been investigated under various conditions of length of the downcomer, radii of inverted U-shaped and U-shaped bends and throttling of the bypass. The stable flow limits and the flow oscillatory characteristics of this instability are made clear for the flow channel conditions.