【作者】 余国安；

【导师】 吕宏兴；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2004， 硕士

【摘要】 我国水资源供需矛盾日益尖锐，但农业用水浪费非常严重，一个不容忽视的原因是我国灌区水量与流量调控技术粗放落后。闸门在灌溉渠道中起着调节流量、控制水位的作用，其开度的变化直接影响到渠道中的水流状况，研究闸门开度变化所引起的渠道水流状况的过渡过程及其影响因素对优化闸门调节方式，从而改进灌区流量调控技术有重要意义。本文对闸门调控下灌溉渠道中的明渠非恒定流过渡过程进行了初步研究。研究内容主要包括两个方面：⑴渠段运行及闸门的调控方式和闸下出流。对灌区常用的上游定水深、下游定水深和常蓄量三种渠段运行方式的优势和不足进行了比较。讨论了闸门的调控方式即顺序调控、同步调控和选择调控的使用情形。对闸孔自由出流和淹没出流时流量和流量系数公式进行了分析和讨论，借鉴 Prabhata 拟合的闸孔出流流量系数函数式，并应用其于本文数值求解圣·维南方程的编程之中。⑵灌溉渠道非恒定流的数值模拟及结果分析。数值模拟采用了矩形网格特征线法，研究对象为由节制闸控制的单个渠段，研究得出的主要结论有：①上游定水深，下游变流量时渠段上游流量和下游水深（或下游定水深，上游变流量时下游流量和上游水深）经历一段时间后都趋于稳定，且流量趋近的稳定值为渠段另一端流量调节的目标值；初始流量和调节时间相同时，流量变幅越大引起的渠段水流波动越大，趋于稳定的时间越长。②在其它条件均相同的情况下，渠段按下游定水深运行优于按上游定水深运行。③在流量调节时段内，闸孔出流流量系数基本呈线性规律变化；在流量调节时段外，流量系数仍有变化，且流量变幅越大，流量系数的变化越强烈，随着闸门上游端水深趋于稳定，流量系数的变化逐渐减弱，最后该系数趋于一个稳定值。④在流量调节时段内，闸孔出流不出现自由出流向淹没出流（或淹没出流向自由出流）过渡时，流量对时间的线性变化几乎对应于闸门开度对时间的直线变化；闸孔出流出现自由出流向淹没出流（或淹没出流向自由出流）过渡时，闸门开度成折线形式的变化，可以拟合成以时间为自变量的线性分段函数。在流量调节时段外，闸门开度呈波浪状，并趋于一个稳定的开度Go稳定，这个开度并不等于流量调节结束时的闸门开度Go调节，在流量变幅为正时，Go稳定较Go调节小；而在流量变幅为负时，Go稳定较Go调节大。⑤本文依据下面三个条件确定了闸门开度的线性调节函数式：闸门调节前的开度值；流量按某一线性规律调节为某一流量时，闸门的稳定开度Go稳定；流量调节时段内闸门开度随时间变化的拟合曲线斜率k 和截距l 。闸门开度按给出的线性函数式调节时，闸孔出流流量随时间基本按线性规律变化；闸孔出流出现自由出流向淹没出流（或淹没出流向自由出流）转变时，流量过程线呈折线，而后流量基本维持稳定不变。更多还原

【Abstract】 Contradiction between water resource’s supply and demand in China is more and moresevere, but the agricultural water waste is very serious, one of the reasons which can’t beignored is the flow regulation techniques in Chinese irrigation districts is backward. Sluicegate are widely used for flow control in irrigation canals, and its opening variation directlyaffects the flow state of the canal. Therefore, analyzing the transition of flow state and itsinfluence factors due to the gate opening change is of great significance to optimize gateregulation mode, and improve flow regulation techniques of the irrigation districts. Unsteady flow transition process in irrigation canals due to sluice gate regulation wasprimarily analyzed in the thesis, which included the following contents: ⑴Canal operation, gate regulation mode and flow through the sluice gate. Theadvantages and disadvantages of three commonly used operation modes in irrigation canals,namely constant upstream water depth, constant downstream water depth and constant watervolume were compared. The adoption condition of gate regulating modes, namely sequentregulation, simultaneous regulation and selection regulation was also discussed. Theequations of discharge through the gate and discharge coefficient under free or submergedflow conditions were analyzed. The discharge coefficient function of the sluice gate, whichwas fitted by Prabhata, was adopted in the programming for the numerical solution of theSaint-Venant equations. ⑵Numerical simulation of unsteady flow in irrigation canals and its result analyses.Rectangular grid Characteristic method was used in the numerical simulation, and theresearch object is a single canal, the main results are: ①When upstream water depth keeps constant and downstream discharge changes,upstream discharge and downstream water depth reached to a stable state after a certain time,and vice versa. The stable discharge at one end of the canal is the regulation object at theother end of the canal. Under the condition of the same discharge and regulating time, thelarger the discharge variation, the longer the time interval needed for the flow to reach stablestate. ②Under the condition of all other state being the same, canals operating in constantdownstream depth is better than in constant upstream depth. ③During the discharge regulating time interval, gate discharge coefficient basicallyvaries in linear mode with time, after the regulating time interval, the coefficient still varies,and the larger the discharge variation, the more severe of the coefficient variation. With thewater depth of the gate tends to stable state, the variation of the coefficient gradually becomeweak and finally it also tends to a stable state.<WP=7>④Within the regulating time interval, and under the condition of discharge through gatehaving no transition from free flow to submerged flow(or submerged flow to free flow), thelinear variation of discharge with time almost corresponds to variation of gate opening withtime; and under the condition of free flow transiting to submerged flow(of submerged flow tofree flow), gate opening variation with time appears in a zigzag line, which can be fitted asdifferent linear functions in different time period. After the discharge regulation, gate openingappears in a waveform, finally it reaches to a stable opening Go稳定 , which is not same to thegate opening Go调节 when discharge regulating finished, Go稳定 is lower than Go调节 whendischarge regulation is positive, while Go稳定 is larger than Go调节 when dischargeregulation is negative. ⑤Linear regulating function for gate opening was derived from the following threeconditions: The gate opening before regulating, stable gate opening after discharge throughthe gate regulated in a certain linear mode, and gradient k and intercept l of the fitted gateopening regulating curve, the discharge through gate varies basically in linear mode whengate regulated更多还原