Lock-in Phenomenon Associated with Self-Sustained Oscillation of Free Shear Layer in a Round Jet

• Published in: Transactions of the Japan Society of Mechanical Engineers Series B Vol. 68; no. 669; pp. 1423 - 1430
• Main Authors: KASAGI, Nobuhide, KURASAWA, Hideo, OBATA, Teruo, HANEDA, Yoshiaki
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society of Mechanical Engineers 2002
• Subjects: Self-Sustained Oscillation
• ISSN: 0387-5016; 1884-8346
• DOI: 10.1299/kikaib.68.1423

The self-sustained oscillation of the shear layer occurs in a round jet impinging on a ring placed coaxially. In the case of the finite length pipe instead of the ring, the oscillating frequency of the shear layer is locked in to the resonant frequency of the pipe in frequency, when both the frequencies approach each other. This study aims at getting a clearer understanding of the lock-in phenomenon in round jet-body system. The experiments are practiced for the four cases. In the two cases a resonator like a pipe is located downsteram to the nozzle exit, in the other two cases a resonator consists of a part of the nozzle with a ring downstream. As a result of the experiments, it has become clear that the lock-in phenomenon takes place in all the cases, but the intensities of the lock-in and the generating resonance are different, depending on whether a resonator is located downstream of the nozzle exit or at the nozzle.