半圆电极对测量壁面处的湍流速度梯度脉动

壁面处湍流速度梯度脉动的测量对于深入了解壁面附近湍流的结构和传热、传质是很重要的.本文叙述了电化学法测量的原理,介绍了用一半圆电极对同时测量壁面上二维湍流速度梯度脉动的方法和测量结果.在直径0.194m的充分发展圆管湍流中,用碘和碘化钾溶液作为流动介质,半圆电极对直径为5×10~-4m,测得壁面处轴向和周向速度梯度的湍流脉动强度分别为0.3—0.33和0.11—0.12.

Employing Semicircular Electrode Pair to Measure Fluctuations of Velocity Gradients on the Wall

Measurement of turbulent velocity gradient on the wall is important for further understanding wall turbulence and mechanism of heat and mass transfer near the wall. This paper describes the principle of such a measurement, and a semicircular electrode pair is suggested for the measuring of the two dimensional fluctuations of velocity gradient on the wall. In a fully developed turbulent pipe flow, with pipe diameter of 0.194m and electrode pair diameter of 5 × 10-4m, using iodine-potassium iodide solution as fluid medium, the measured axial and transverse turbulent intensities of velocity gradients are 0.3-0.33 and 0.11-0.12 respectively.