U形渠道流速分布特性分析与试验

依据室内试验和田间实测资料,分析了U形渠道水流流速分布特性,建立了U形渠道水流横向流速分布指数律、垂向流速分布双幂律,给出了相关参数的确定方法,并提出了基于U形渠道水流分布规律的明渠测流计算断面中线“三点法”.实测资料验证表明:中线“三点法”在室内不同工况计算流量相对误差均在±4％范围内；除个别测点外,现场实测计算流量相对误差也在±5％范围内,说明中线“三点法”计算精确.与流速-面积法需9个测点相比,中线“三点法”节省了60％以上的测流工作量.

Analysis and Experiment of Distribution Properties and Its Application of Velocity in U-shaped Open Channel

Based on indoor and field experiments, velocity distribution properties of U-shaped open channel were analyzed. Exponent formula for horizontal velocity distribution properties and two-power law for vertical velocity distribution properties were established. The methods to define the parameters were given. Then the midline three-point for flow measurement of open channel was put forward based on the velocity distribution properties of U-shaped channel. The fractional errors of flow velocities calculated by the midline three-point method in indoor experiment under different operating conditions and field experiment were within ±4% and ±5%, respectively. Validations showed that the midline three-point method increased the computational accuracy of flow measurement in open channel. In addition, the workload of the flow measurement by the midline three-point method was substantially reduced by more than 60% compared with velocity-section method which needed nine measuring points.