Application of an Array of Four Phase-detection Probe Sensors to Hydraulic Jumps at Large Reynolds Numbers

摘要

The measurement of turbulent velocity is difficult in hydraulic jumps with relatively high Reynolds numbers because of the presence of entrained air bubbles. This study presents a method aimed to characterise the three-dimensional velocity field in hydraulic jumps using a four-sensor phase-detection probe array. Besides the longitudinal velocity and turbulence intensity that were measured for both positive and negative velocity flow regions, a characteristic instantaneous transverse velocity component was derived together with a measure of its fluctuations. The transverse velocity component characterised the three dimensional nature of turbulent structures. Although the time-averaged flow pattern was two-dimensional and the average transverse velocity was zero, the transverse velocity fluctuation was found to be one order of magnitude smaller than the longitudinal velocity fluctuation.