摘要
提出了一种适合于复杂流动下泥沙起动概率的测量方法——图像测量法.该方法对床面上砂颗粒的运动图像进行采集,根据采集到的图像采用互相关算法计算出砂颗粒的运动速度,由砂颗粒运动速度得到泥沙的起动概率.采用该方法测量了槽道流动及后台阶流动2种情况下床面泥沙的起动概率.在槽道流动下,床面泥沙的起动概率随着床面剪应力的增大而增大.由本文测量方法得到的临界起动剪应力与希尔兹曲线所得到的结果相一致.在后台阶流动下,测量结果表明,再附点附近处泥沙的起动概率最大.这一结果能够解释在后台阶下游床面局部冲刷实验中发现的再附点附近冲刷最为严重的现象.
A technique based on image process, which is suitable to measure the probability of sediment incipient under complex flow, was presented. The sediment motion image was grabbed and transformed to digital image. Base on the digital image, the cross correlation method was used to calculate the velocity of sediment particles. The probability of sediment incipience was obtained by the velocity of sediment particles. This technique was employed to measure the sediment incipience probability in two cases： the flow in the channel and the backward-facing step flow. In the case of flow in the channel, the sediment incipience probability increased with the bed shear stress. The critical incipient shear stress obtained by the presented method agreed with that obtained by Shields curve. In the case of backward-facing step flow, the maximum incipient probability was found near the reattachment point, which accounted for the phenomenon, in which the maximum depth of scouring hole appeared near the reattachment point in the experiment of the local scouring process at the downstream of backward-facing step.
出处
《湖南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2008年第3期24-27,共4页
Journal of Hunan University:Natural Sciences
基金
国家自然科学基金资助项目(10602017)
关键词
泥沙
起动概率
图像测量
局部冲刷
sediment
incipience probability
image measurement
local scouring
