二次元乱流噴流の乱流領域と非乱流領域との界面に関する研究

概要

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The interface between the turbulent and non-turbulent region in a two-dimensional turbulent jet is investigated by the simultaneous measurement of velocity and pressure. The measurements are performed using a combined probe comprising an X-type hot-wire probe and a static pressure probe. The measurement data are analyzed by the conditional sampling technique and an ensemble averaging technique on the basis of the intermittency function for the turbulent/non-turbulent decision. The measurement results at the cross-streamwise edge of the turbulent region show that there is a thin interfacial layer associated with a sharp jump of physical quantities (such as mean streamwise velocity) at the cross-streamwise edge of the turbulent region, and the thickness of interfacial layer is found to be 0.08 times the half-width of the cross-streamwise profile of the mean streamwise velocity. Moreover, the possibilities that there are small vortices in the middle of the interfacial layers and the existence of these vortices contributes to the transport of fluctuation pressure to the non-turbulent region are shown.