【作者】 洪成；

【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， 2005， 硕士

【摘要】 本文对灌区现有的常用量水设备进行了总结,并指出了这些量水设备的优缺点及使用条件。在此基础上,分析得出从经济实用、稳定可靠角度出发,槽类量水建筑物应该是灌区最适合、最易大范围推广应用的量水设施,未来槽类量水建筑物的开发和研究,应该是解决灌区量水问题的主要途径。在导师指导下,本文提出了一种新型的U 形渠道量水槽,即机翼形量水槽,为了分析论证其在U 形渠道上应用的可行性、实用性,并探讨其量水特性,本文选取了8 种不同收缩比的机翼形量水槽分别在西北农林科技大学教育部旱区农业水土工程重点实验室和水工厅进行了试验研究,并取得了一定的研究成果。通过试验和理论分析得出机翼形量水槽在自由出流状态下的两种流量公式,流量公式仅与槽前水深有关,计算方便、简单。两种流量公式的测流精度高,其中系数法得出的半经验半理论流量公式测流平均误差为1.07%,直接拟合法得出的流量公式测流误差为0.97%,符合明渠测流规定的测流误差不大于5%的规范要求。试验结果表明:机翼形量水槽具有较高的临界淹没度。临界淹没度高达0.88,高于U 形渠道直壁式量水槽的临界淹没度(0.84)、半圆柱量水槽的临界淹没度(0.8) 和巴歇尔量水槽的(0.6-0.8)。这种高淹没度,更能在大范围内保证机翼形量水槽在自由出流状态下工作。同时得出机翼形量水槽在小流量、小水深情况下,临界淹没度比大流量、大水深情况时相对大一些,一般可以不考虑淹没的影响。　试验得出,收缩比对流量影响较大。同一水深下,收缩比较大的量水槽过流量较大,收缩比较小的量水槽过流量较小。机翼形量水槽的流量与收缩比成正比,流量随收缩比增大而增大,并且这种规律与U 形渠槽水力条件无关;机翼形量水槽水头损失比较小,水头损失占U 形渠槽上游总水头的8%左右。佛汝德数Fr 是衡量渠槽水流状态的一个指标,堰槽测流一般要求佛汝德数Fr 小于0.5,以保证不形成驻波能够得到精确的水头。试验结果表明,机翼形量水槽佛汝德数Fr 基本小于0.5,仅有个别点据数值稍大于0.5,符合测流要求。　　　　　本文系统的提出并分析了机翼形量水槽在U 形渠道上量水的特性和实际应用的可行性,从试验研究和理论分析中可以得出,机翼形量水槽具有测流精度高、水头损失较小、淹没度和临界淹没度较高、构造简单、外形美观等优点。研究结果表明,机翼形量水槽可以作为一种新型的U 形渠道量水设施,具有一定的实际应用价值。更多还原

【Abstract】 This text carries on the brief introduction towards measuring water equipments and the condition of using. On the base of economy and stable dependable angle, the kind of slot measuring water building should be the most suitable match, the biggest scope expanding measuring water facilities, in the future the development of slot measuring water building and research, should be main path that resolves problem of measuring water. Guide at the tutor under, this text put forward a kind of new U form channel measuring water slot, namely the plane wing form measuring water slot, for analyzing it is on the U channel applied possibility,practicality,and discussing the characteristic of measuring water. The writer selected 8 kinds of different contract ratio plane wing form measuring water slot and carry on great trial research in the college irrigation station and water work halls, and obtained the certain research result. Passing to experiment and the theories analysis ,find two kinds of discharge formula at the free flow appearance , the discharge formula is deeply relevant with deepness before slot only, and computing means is simple。Two kinds of discharge formulas’precision is all very high, among them, the half experience half theories the discharge formula average error only is 1.07%, simulating directly mean error is 0.97% , matching criterion’s error no bigger than 5% norm request. Experimental result: The plane wing shape measuring water slot has higher submergence degree and critical submergence degree. The submergence degree between 0.92 and 0.85,the critical submergence degree is up to 0.88,up U form channel straight wall slot’s critical submergence degree (0.84) and the semicircle pillar measuring water slot’s critical submergence degree (0.8). This kind of high submergence degree, even can guarantee that the plane wing form measuring water slot work well in free pouring in large scope. At the same time still finding out, the flux is smaller; the critical submergence degree is bigger. So the plane wing form measuring water slot at small flux doesn’t appear submerge and pour easily. From experiment, it is found that the constringency ratio has influence on flux greatly. In the same water deepness, the constringency ratio is greater, and the flux is greater; the constringency ratio is smaller, and the flux is smaller. The plane wing form measuring water slot’s flux is in proportion to the constringency ratio, and, the flux become larger along the constringency ratio become larger, and the rule is independent of the condition of channel; The plane wing form measuring water slot’s water head lose smaller, general low in 3.5 cm, and the water head losing has 8% of the total head of water only .The Froude number is an important index sign that scale the channel slot water current appearance, the flow measurement of open channel request the Froude number is small in 0.5 .Experiment the result show that the plane wing form measuring water slot’s Froude number is small in 0.5,and the individual point only is slightly big to 0.5, match the request of the flow measurement of open channel . This text is the first systemic puts forward and analyzes the plane wing form measuring water slot’s applied possibility and practicality on the U channel, from experiment research and theories analysis can get that the plane wing measuring water slot has the excellence of the accuracy high, the water head losing smaller, the submergence degree higher, critical submergence degree higher, structure simple, shape beauty etc. advantage. The studying result show that the plane wing form measuring water slot can be a kind of new U channel measuring water facilities, certainly have actual application value.更多还原