Experimental studies on the Reynolds stress in an open channel flow

通过对明渠水流时间序列数据的分析，对雷诺应力进行了实验研究。在室外农业灌溉渠道，即爱知县的明治灌溉渠道和岐阜县的Makuwa和Kagami灌溉渠道进行了实验。仪器系统由螺旋桨式小电流计、数据记录仪、频率电压转换器和监测记录仪组成。主要研究结果如下：1.结果表明，小流速仪的时间常数在正常流速下约为0.03-0.05秒，在流速方向上可用余弦函数近似。2.自相关图的模式在明渠流的下部比在上部陡峭。积分时间尺度为0.04-0.01秒。3.能谱密度的形状随着频率的升高而逐渐变小，没有特别的峰值。4. u和w平均模式之间存在负相关。5.采用条件抽样法分析了雷诺应力结构。

Experimental studies on the Reynolds stress were practised by analyzing the time series data in an open channel flow. Experiments were performed at the outdoor agricultural irrigation channel, that is, the Meiji irrigation channel in Aichi prefecture and the Makuwa and Kagami irrigation channel in Gifu prefecture. Instrumental system was composed of a small current meter of the propeller type, a data recorder, a frequency-voltage converter and a monitor recorder. The results obtained were as follows.1. It was found that the time constant of a small current meter was about 0.03-0.05 seconds for the usual flow and was well approximated by the cosine function in the direction. 2. The patterns of the auto-correlogram in the lower parts of the open channel flow were steeper than in the upper parts. The integral time scales were 0.04-0.01 seconds. 3. The shape of the energy spectral density gradually decreased with the high frequency and didn't have a any particular peak. 4. There was a negative correlation between the recognized u and w averaged patterns. 5. The conditional sampling method was carried out to analyze the Reynolds stress structure.