円管内脈動乱流の摩擦抵抗低減に関する実験的研究(流れの制御(2),一般講演)

概要

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Drag reduction phenomenon of pulsating turbulent pipe flow is experimentally examined. The rotating speed of a centrifugal pump was periodically changed for generating the pulsating flow. The time-averaged friction Reynolds number is set to be 110 for comparison with the previous data of direct numerical simulation (DNS). It is found that the drag reduction and the energy saving rates are increased with increasing the mean pressure gradient in the acceleration phase and that an optimal value of the pulsating period exists. The overall trend is qualitatively similar to that of the previous DNS data. The maximum drag reduction and the energy saving rates are respectively 33% and 22% when the time period normalized by the friction velocity and the radius is 10.6 and the mean pressure gradient in the acceleration phase is 4.1 times as large as the cycle-averaged mean pressure gradient.
日本流体力学会の論文
2008-09-04