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建立了一套高精度的明渠非恒定流试验系统,并进行了多组正弦型明渠非恒定流试验以详细研究明渠非恒定流的传播特性.通过试验数据分析获得了明渠非恒定流的传播速度、波的变形率、波峰和波谷的外包线等参数的变化规律.结果表明:(i)明渠非恒定流的传播速度可以用波峰时的微波波速及流速之和来表示;(ii)非恒定流传播过程中会发生时间尺度上波的变形,上升段变短而下降段变长,但总的时间仍然保持不变,变形率是传播距离、周期和流量波幅的函数;(iii)波峰、波谷的水深同周期关系密切,当周期减小时,波峰、波谷水深均逐渐靠近平均流量对应的均匀流水深,当周期变大时,波峰水深靠近最大流量对应的均匀流水深,波谷则靠近最小流量对应的均匀流水深;(iv)非恒定流传播过程中,流量随不同周期的变化规律同水深变化规律基本类似.
A set of high-precision open channel unsteady flow test system was established and a series of sinusoidal open channel unsteady flow tests were carried out to study the propagation characteristics of open channel unsteady flow in detail.The propagation velocity of open channel unsteady flow was obtained by experimental data analysis , The deformation rate of the wave and the envelope of the wave crest and trough.The results show that: (i) the propagation velocity of the unsteady flow in the open channel can be expressed by the sum of the wave velocity and the flow velocity at the crest; (ii) Wave deformation occurs on a time scale in the flow propagation process, the ascending section becomes shorter and the descending section becomes longer, but the total time remains unchanged, and the deformation rate is a function of propagation distance, period and flow amplitude; (iii) When the period decreases, the water depth of crest and trough gradually approaches the average depth of water corresponding to the average flow rate. When the period becomes larger, the water depth of crest is close to the average depth of water corresponding to the maximum flow rate, while the trough is close to the minimum flow rate Corresponding to the uniform flow depth; (iv) during the unsteady flow propagation, the variation of flow with different periods is basically similar to the variation of water depth.