単相閉ループ内自然循環特性に関する研究 : 第1報,逆U字形クーラを有する場合の実験結果

An experiment on single phase natural circulation was conducted in a closed loop with a U-shaped cooler. The loop consists of an inverse U-shaped tube cooler, two parallel heating boxes and connecting bent pipes. Tests were made at atmospheric pressure by holding the heater input (Q=0.5 kW to 3.5 kW) constant, and the cooling water flow rate of the cooler constant, during various transient elevation differences between the heater and the cooler. The observed transient flows were classified as three regimes : stable, neutrally stable, and unstable type, the flow developed a reverse flow and, afterwards, it oscillated with a periodic reversal of flow. A characteristic of the flow oscillation was described with relation to the period and the length of flow path, and the oscillation mechanism was discussed for the change of buoyancies and flow. The flow oscillation was found to stem from the flow change in the inverse U-shaped flow paths of the cooler and the hotleg, including the heater.