3段エルボ配管における旋回流流入時の複雑流動場の詳細可視化実験

Visualization experiment of complex flow fields in a triple elbow piping system under swirling inflow conditions

水谷 淳*; 江原 真司*; 橋爪 秀利*; 山野 秀将   

Mizutani, Jun*; Ebara, Shinji*; Hashizume, Hidetoshi*; Yamano, Hidemasa

本研究では、旋回流生成器を用いて様々な旋回流が流入する際のエルボ内部および下流の流れを実験的に評価し、速度変動場について発達乱流流入時と比較を行った。旋回流流入時は1stエルボ下流での定常的な剥離は生じないが周期性の弱い長周期の渦放出が生じる。また管壁に沿って背側から腹側に向かう流れは入口旋回流の方向は強く、逆方向は弱くなり、この2つの流れが異なる周期で生じていることが示唆された。2ndエルボ下流では速度変動の周期性については発達乱流流入時と旋回流流入時では大きな差異はなく、入口における流入条件の影響が相対的に小さくなり、エルボ配管により決まる流れの矯正が支配的になることが分かった。

This study evaluated experimentally the effect of influence of the inflow condition upon the flow field in the cold leg piping of the primary cooling system of a sodium-cooled loop-type fast reactor by using a swirling flow generator. Flow visualization with the two-dimensional particle image velocimetry was conducted to reveal the velocity fields of the flow in the piping, especially fluctuating velocity fields, and the results were compared to those obtained from the fully-developed turbulent inflow case. The experiment showed that the there appeared long-period vortices shedding with weak periodicity from the intrados of the 1st elbow instead of steady vortices shedding from flow separation region. In the 2nd elbow, the periodicity of fluctuating velocities were not largely different from those obtained in the fully-developed turbulent inflow case. The downstream of the 2nd elbow was not largely affected by the inflow condition.