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在灌溉渠系上,通常用侧堰分流(图1)。本文推导出一个公式,用以计算渠道和侧堰均为梯形时的出流量,并提供了检验该公式合理性的实验结果。 1.理论公式推导梯形渠道上侧向梯形堰水流特征公式推导非常类似于早期所报告的矩形堰流公式的推导。把堰流视为若干侧向出流的无限小微分水流层的水流的总和,对于平面水流,当渠道水面宽为B,侧堰上口宽为L时,其流量系数C_4定义为: C_d=单位深度的堰流量/LV_i (1)
In irrigation canal systems, it is common to divert side-weirs (Figure 1). In this paper, a formula is deduced to calculate the outflow when both the channel and the side weir are trapezoidal and provide the experimental results to test the rationality of the formula. 1. Theories and formulas The derivation of the formula for the trapezoidal flow characteristics of the trapezoidal weir on the trapezoidal channel is very similar to the derivation of the rectangular weir flow formula reported earlier. The weir flow is regarded as the sum of the water flows of several small inflow streams with lateral outflow. For the planar water flow, the flow coefficient C_4 is defined as C_d = Weir flow per unit depth / LV_i (1)