リングかく乱を受けた円管内乱流の平均流場の測定

概要

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The response of a fully developed pipe flow to an attached ring-type manipulator with rectangular cross section was investigated by measuring the mean velocity profiles. The ring-type element has a height of 0.14 times the pipe radius and was positioned rigidly in a 99.8-mm diameter, smooth-walled, circular pipe in which air was flowing at Reynolds number of 6.2×10^4. The results indicate that the flow in the core is significantly perturbed and the return of the flow to a self-preserving state without disturbance has been achieved at about 960 times the manipulator height. Furthermore, near the reattachment point, the mean velocity profile in the core region of the pipe is much more uniform and the velocity gradient is steeper near the wall than in a smoth pipe, indicating enhanced mixing. The boundary layer characteristics, such as the skin friction coefficient and boundary layer thickness are also altered in the streamwise direction upon a pulsewise disturbance.
1995-06-25