开孔促淤板周围水流紊动特性试验研究

为深入了解开孔促淤板周围的水流特性,通过室内概化水槽试验分析了开孔促淤板前后的水流紊动特性,采用声学多普勒流速仪(ADV)测量了开孔促淤板前后典型断面上的三维瞬时流速,分析了典型断面上的时均流速、紊动强度、雷诺切应力和紊动能的分布规律。试验结果表明:板后近板区出现回流区,且回流区与开孔促淤板格栅位置相对应；板后水流相对紊动强度、雷诺切应力及相对紊动能明显大于板前,开孔促淤板对板后近板区水流影响较大；随着与开孔促淤板距离的增大,回流现象消失,流速变化趋于稳定,水流相对紊动强度减小且最终趋于稳定,相对紊动能出现折减且折减率逐渐降低；靠近近板区xOy面雷诺切应力大于yOz面雷诺切应力,靠近下游xOy面雷诺切应力与yOz面雷诺切应力相差较小。

Experimental study on turbulence characteristics of water flow around a perforated siltation-promoting plate

To have a deep insight into the turbulence characteristics of water flow around a perforated siltation-promoting plate, the change law of the turbulence characteristics before and after the plate was analyzed through an indoor generalized water tank test. The three-dimensional instantaneous flow velocity on the typical sections before and after the perforated silting-promoting plate was measured by acoustic Doppler velocimetry (ADV), and the distribution law of time-averaged flow velocity, turbulence intensity, Reynolds shear stress and turbulent kinetic energy at typical sections were also analyzed. The test results show that there is a recirculation zone in the area near the plate back, and the recirculation zone corresponds to the position of the grille of the perforated siltation-promoting plate. The relative turbulent intensity, Reynolds shear stress and relative turbulent kinetic energy behind the plate are significantly larger than those in front of the plate. The plate has a great influence on the flow in the area near the plate back. With the increase of the distance from the perforated siltation-promoting plate, the recirculation phenomenon disappears. The change of the flow velocity tends to be steady, the relative turbulent intensity decreases and finally tends to be stable, and the relative turbulent kinetic energy decreases with a decreased reduction rate. The Reynolds shear stress at the xOy plane close to the near-plate area is greater than that at the yOz plane, and the Reynolds shear stress at the xOy plane adjacent to downstream is close to that at the yOz plane.