| 引用本文: | 韩 宇,吴章生,马壮壮,等.基于流速分区理论的半圆形明渠测流点布控方法研究[J].灌溉排水学报,2019,38(11):42-48. |
| ,et al.基于流速分区理论的半圆形明渠测流点布控方法研究[J].灌溉排水学报,2019,38(11):42-48. |
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| 摘要: |
| 【目的】针对半圆形渠道进行物理模型试验研究，揭示半圆形渠道沿壁面法线方向平均速度特征位置的分布规律，为非标准断面渠道测流方法提供新思路。【方法】基于不同水力条件下渠道断面流速的量测结果，从流速分区理论出发，利用经典对数公式推导半圆形渠道断面测速法线上平均流速特征位置点的理论计算公式，考虑侧壁对摩阻流速的影响，基于测定特征位置的流速从而得到整个半圆形渠道断面的平均流速。【结果】本研究提出半圆形明渠在过圆心的测速法线上平均速度特征位置的计算公式，与试验结果相比，该公式计算结果所得平均误差在10%左右，该公式能较好地反映半圆形明渠测速法线平均速度特征位置的分布特性；沿测速法线方向分析半圆形明渠断面流速分布精度更高，流速分布规律的分析也更加合理。【结论】平均流速特征位置点理论公式计算结果与模型试验结果较为吻合，公式精度较高，工程中可通过测量特定位置的点的流速进而推求断面平均流速，达到快速准确确定渠道断面流量的目的。 |
| 关键词: 流速分布； 对数定律； 剪切力； 分区理论 |
| DOI：10.13522/j.cnki.ggps.20190257 |
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| Mean Velocity Measuring Point of Semi-circular Open Channel Section Based on Flow Partitioning Theory |
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HAN Yu, WU Zhangsheng, MA Zhuangzhuang, LI Tongshu, CHEN Jian, HE Xiangli
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China Agricultural University, Beijing 100083, China
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| Abstract: |
| 【Objective】 The purpose of this paper is to reveal the characteristic position of the mean velocity along the normal line of the semi-circular channel wall and provided a novel method for flow measurement in non-uniformed channel, the physical model experiments were conducted in semi-circular channel. 【Method】Based on the measuring results of flow velocity under different hydraulic conditions, the theoretical formula for calculating the mean velocity characteristic position along the normal line of the semi-circular channel wall was derived from flow partitioning theory. Considering the influence from side wall to friction velocity, the mean flow velocity of the entire semi-circular channel section can be obtained by measuring the flow velocity at the characteristic location. 【Results】This paper proposed the theoretical formula and the measurements achieved a good agreement within 10% error. The formula can clearly reflect the distribution of the semi-circular open channel well. The velocity distribution should be analyzed along the normal line， thus the analysis methods was more reasonable. 【Conclusion】The theoretical results on determining mean velocity characteristic position fitted well the results from experiment and it indicated the formula has higher precision. The flow velocity at a specific position can be measured to further estimate the mean flow velocity of the section, so as to quickly and accurately determine the flow rate of the channel section in the project. |
| Key words: velocity distribution; log-law; shear force; flow partitioning theory |
