应用PTV粒子追踪测速技术的鱼卵运动试验研究

Experimental research on fish eggs' movement using particle tracking velocimetry technique

鱼卵运动研究是了解自然河流中鱼卵漂流散布规律的力学基础,对鱼类早期资源估算、产卵场位置推算和鱼类栖息地修复等具有重要意义。本文应用PTV粒子追踪测速技术,通过20组不同水深、不同流速工况的水槽试验和200组鱼卵粒子群(直径为4 mm,比重为1.01)运动视频的图像处理,并结合理论推导解析鱼卵运动方程,系统分析了恒定均匀流条件下的鱼卵运动特性、主要影响因素及其作用机理。结果表明,鱼卵运动的主要影响因素为水流速度、鱼卵比重、鱼卵粒径和鱼卵初始速度。鱼卵纵向速度随水流纵向速度线性增大,其试验拟合结果为水流纵向速度的0.73倍;鱼卵垂向速度(沉速)主要受鱼卵比重和粒径的影响,与水流纵向速度无直接显著关系;鱼卵运动轨迹在小流速情况下近似线性下降,且轨迹斜率随流速增大而趋缓;当流速增大到0.93 m/s,鱼卵轨迹受水流紊动效应影响转变为伴随着个别鱼卵猝发跃移的波浪翻滚式下沉;水深对鱼卵运动速度和运动轨迹的影响相对微弱;鱼卵初始速度对其运动的影响仅在初始极为短暂的时间内。

The study of fish eggs＇ movement is a mechanical basis for understanding the rule of fish eggs＇ drifting and dispersing in natural rivers. It is of great significance in the estimation of early-stage fish abun-dance,the evaluation of spawning ground location and the ecological restoration of fish habitat. In order toreveal the characteristics,the main impact factors and impact mechanism of fish eggs＇ movement under thesteady uniform flow in open channel,20 groups of flume experiments with varying water depths and veloci-ties were carried out and 200 videos of fish eggs＇ movement（eggs＇ diameter=4 mm,specific gravity=1.01）were recorded and processed by particle tracking velocimetry（PTV） technique, a theoretical derivation ofeggs＇ movement equations was also performed in this paper. The results show that the main impact factorsof fish eggs＇ movement are the flow velocity, the fish eggs＇ specific gravity, the eggs＇ diameter and theegg＇initial velocity. The eggs＇ longitudinal velocity is linear increasing with the increasing flow longitudinalvelocity and the fitting linear coefficient is 0.73 which meant the eggs＇ longitudinal velocity is about 0.73 times to the flow longitudinal velocity. The eggs＇ vertical velocity is mainly affected by the eggs＇ specificgravity and diameter,and has no significant relationship with the flow longitudinal velocity. In the lower ve-locity condition, the trajectories of eggs＇ movement had a linear decrease trend and the slope of trajecto-ries slowed down with the increasing flow velocity. When the velocity increased to 0.93 m/s, the trajectorychanged from simple linear sinking to the wave-and-roll type sinking, and some individual eggs jumpedsuddenly. The impact of flow depth on the eggs＇ velocity and trajectory is relatively small. The effect ofeggs＇ initial velocity on the eggs＇ longitudinal vertical velocities were only in the initial short time.