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。试验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。仪器系统由螺旋桨式小流速仪、数据记录仪、频率-电压转换器和监测记录仪组成。研究结果如下：1.研究结果。结果表明，对于通常的流量，小流速仪的时间常数约为0.03-0.05秒，并能很好地用方向上的余弦函数逼近。2.明渠水流自相关图的下部比上部陡峭。积分时标为0.04~0.01秒。3.随着频率的升高，能谱密度的形状逐渐减小，没有任何特定的峰值。4.识别出的u和w平均图形之间存在负相关。5.采用条件采样法对雷诺应力结构进行了分析。

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.