CAJ | 학술논문

为了通过实验测量泥沙起动概率, 基于封闭槽道内开展的泥沙起动实验, 系统论述了基于高速摄影的起动概率测量方法所涉及的起动概率定义、相机采样频率、图像处理方法、起动比例与运动比例的关系等关键问题.根据泥沙在水流紊动猝发作用下起动的物理机制, 定义实测起动概率为单个紊动猝发周期内, 从一定面积床面上冲刷外移的泥沙比例. 根据推移质运动概念模型, 提出高速图片拍摄间隔应小于推移质运动的中间时间尺度, 以捕获泥沙的每一次起动. 在高速图像处理时, 通过连续两帧图片之间的灰度差实现运动比例的无偏差提取. 进一步分析表明, 运动泥沙可处于起动、止动或滑翔状态, 运动比例等于起动比例、止动比例和滑翔比例之和, 起动比例与运动比例之比等于两张图片之间的时间间隔除以推移质运动的中间时间尺度. 基于上述关键技术, 将高速摄影测量方法用于泥沙起动概率的测量, 结果表明, 临界起动水流条件时, 床沙处于少量起动现象, 对应的临界起动概率与窦国仁所推导的2. 28%接近.
위료통과실험측량니사기동개솔, 기우봉폐조도내개전적니사기동실험, 계통논술료기우고속섭영적기동개솔측량방법소섭급적기동개솔정의、 상궤채양빈솔、 도상처리방법、 기동비례여운동비례적관계등관건문제.근거니사재수류문동졸발작용하기동적물리궤제, 정의실측기동개솔위단개문동졸발주기내, 종일정면적상면상충쇄외이적니사비례. 근거추이질운동개념모형, 제출고속도편박섭간격응소우추이질운동적중간시간척도, 이포획니사적매일차기동. 재고속도상처리시, 통과련속량정도편지간적회도차실현운동비례적무편차제취. 진일보분석표명, 운동니사가처우기동、 지동혹활상상태, 운동비례등우기동비례、 지동비례화활상비례지화, 기동비례여운동비례지비등우량장도편지간적시간간격제이추이질운동적중간시간척도. 기우상술관건기술, 장고속섭영측량방법용우니사기동개솔적측량, 결과표명, 림계기동수류조건시, 상사처우소량기동현상, 대응적림계기동개솔여두국인소추도적2. 28%접근.
We present a novel, high-speed imaging method for measuring the pickup probability for sediment entrain-ment under flowing water. The pickup probability is defined as the proportion of sediment particles entrained from a given bed region during a turbulent bursting period, so the measurement necessitates a least sampling frequency corre-sponding to the intermediate range of sediment motion. Moving particles are identified by examining the gray difference between two successive images, and the probability for sediment motion is determined by counting the number of parti-cles in motion. The pickup probability equals the probability for sediment motion times the interval between two con-secutive images divided by the intermediate temporal range. The method has been successfully applied to the measure-ment of bed-load transport in closed channel flows. Preliminary results show that the measured pickup probability for sediment entrainment at critical conditions remains at 2. 27%, similar to previous results in the literature.