4232 旋回逆流の振動特性に及ぼす入口曲管の影響(G05-14 管内流・旋回流,G05 流体工学)  [in Japanese] 4232 Effects of Bent inlet on the Swirling Backflow Oscillation  [in Japanese]

The present paper describes the experimental study of effects of a bent inlet on the swirling backflow oscillation. The backflow is generated by using a 4-bladed swirler with zero stagger. The tests were carried out by particle image velocimetry (PIV) in the region between bend and swirler. The backflow length fluctuations measurements show spread to the axial direction with increasing swirling speed, and its unsteadiness become stronger. Results of spectrum analyses of backflow length fluctuations show three oscillation patterns. At low swirling speed, the backflow oscillation has one dominant frequency. With increase of swirling speed, dominant frequency of the backflow oscillation shift lower frequency and it has two peaks on spectrum analysis.