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Second Symposium on Turbulence and Shear Flow Phenomena
June, 27-29, 2001, KTH, Stockholm, Sweden

DOI: 10.1615/TSFP2

THE SHEAR LAYERS OF A 2D JET EXCITED BY SMALL FLEXIBLE WIRES

pages 41-46
DOI: 10.1615/TSFP2.1700
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要約

The shear layers of a 2D hot jet, interacting with flexible fine wires, are investigated experimentally. The jet width is 15mm, and the jet nozzle has an aspect ratio of 20:1. The ratio of the jet-exit density to the ambient is 0.8, and the Reynolds number of the jet is 3000 approximately. In each shear layer of the 2D jet flow, a fine wire of diameter 0.23mm is flexibly mounted along the span-wise direction. The natural frequency of the wire is regulated by the tension in the wire. The interaction of the wires and the jet flow is investigated by temperature measurements and flow visualization. It is found that the flexible wires are more likely to vibrate when they are mounted in the shear layers with high mean velocity gradient rather than in the potential core. The flexible wires when located in the shear layers have significant influence on the jet flow. With the wires being still in the shear layers, the jet potential core becomes longer, and temperature fluctuations in the near field are suppressed slightly. With the wires vibrating in the shear layers, the jet flow is influenced profoundly; the potential core becomes much shorter, the coherent structures in the shear layers appear closer to the jet nozzle, and the hot jet spreads more heat in the cross-stream direction and the temperature fluctuations in the shear layers increase significantly. Furthermore, the temperature spectra of the hot jet become line-dominated with the spectral peaks occurring at the natural frequency of the wire and its harmonics. Thus, the dominant frequency of the jet can be controlled by adjusting the natural frequency of the wire, through adjusting the wire tension in the experiment.

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