摘要
田间量水是实现灌区计划用水和节水农业的关键技术,末级小截面灌区的精准测流则更为关键。该研究在机翼形量水槽的基础上,提出结构更为简单的仿机翼形量水设备。水工模型试验于西北农林科技大学水工与水力学实验室进行,试验渠道为17 m×70 cm×100 cm的矩形断面有机玻璃渠道,量水槽模型均采用空心木制材料制作。试验设计1组翼长、6组收缩比、7组流量,共42种试验方案。在水工模型试验的基础上,采用FLOW-3D软件补充了多组模型进行数值模拟,验证模拟准确性后,对其水力性能进行分析:上游佛汝德数小于0.5,喉口位置产生临界流,下游重新恢复缓流状态;壅水高度均值3.25 cm,最大值6.32 cm,最小值0.46 cm;水工模型试验与数值模拟共获得84组数据,依据机翼形量水槽的测流公式推导,得到仿机翼形便携式量水槽的测流公式,其平均相对误差为6.34%。仿机翼形便携式量水槽建议选择收缩比0.606~0.709、翼长65~80 cm。研究表明简化并没有改变机翼形量水槽原有的优点,可以保证测流渠道的安全性。该研究可改进量水方法,提高用水效率,对于促进中国灌区小截面便携式量水槽的推广具有实用价值。
Accurate,simple,and rapid water measurement in the field is highly required for the planned water use and water-saving agriculture in most irrigation areas,particularly in the last small cross-section irrigation districts.In this study,a measuring device was proposed in an airfoil-like shape with a simple structure,according to the conventional airfoil-shaped flow measuring flume.The simple structure of the airfoil-shaped measuring device was applied to the small cross-section flow measurement of the rectangular channel.A hydraulic model test was carried out in the Laboratory of Hydraulic Engineering and Hydraulics of Northwest A&F University of China in 2020.A plexiglass rectangular channel flume was designed with a size of 17 m×70 cm×100 cm.Flow flume models were all made of hollow wooden materials.A total of 42 test schemes were designed,including 1 set of airfoil length,6 sets of contraction ratios,and 7 sets of flow rates.A better hydraulic performance was presented in the numerical simulation than before,such as Froude number and flow streamline.A FLOW-3D software was also used to supplement several sets of models to evaluate the simulation accuracy,and the hydraulic performance.Specifically,the upstream Froude number(less than 0.5)was verified to meet the national standard requirements.The position of the throat produced the critical flow,whereas,the downstream resumed the slow flow.The average height of backwater was 3.25 cm,while the maximum was 6.32 cm,and the minimum was 0.46 cm.A total of 84 datasets were obtained from the hydraulic model test and numerical simulation.The flow formula of the portable airfoil-shaped flume was achieved,where the average relative error was 6.34%,meeting the requirements of the last small cross-section channel.The flow rate range of the flume was 15.3-47.2 L/s.An optimal combination of hydraulic parameters was achieved,where the range of shrinkage ratio from 0.606 to 0.709,with an average error of 6.95%under shrinkage ratio of 0.606,while 4.91%under shrinkage ratio of 0.709.The airfoil length ranged from 65 to 80 cm,all of which were suitable for the specific irrigation area.Correspondingly,it was suggested that the airfoil length ranged from 65 to 80 cm,when the channel width was 70 cm in the practical field.In addition,the double channel in the flow measurement device demonstrated that the entrance was flush,and the central axis was parallel in the center of the rectangular water tank.There was no gap between the bottom of the fixture and the channel surface during installation.The symmetrical model was well sealed at the joint of the central axis of the channel for a higher accuracy of flow measuring precision.Consequently,the simplified airfoil-shaped flume can be expected for the higher safety of measuring channel,concurrently remaining the excellent performance.This finding can provide a promising economic and practical support to the higher performance of measuring water and the efficiency of water use,particularly to the popularization of small-section portable flow measurement flume in most irrigation districts.
作者
贺梦杨
尚海鑫
张宽地
凌鹏
He Mengyang;Shang Haixin;Zhang Kuandi;Ling Peng(College of Water Resources and Architectural Engineering,Northwest A&F University,Yangling 712100,China;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resource,Yangling 712100,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第12期117-124,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金资助项目(51579214,41877076)。
关键词
流量测量
数值模拟
便携式设备
仿机翼形
矩形渠道
flow measurement
numerical simulation
portable equipment
imitated airfoil shape
rectangular channel
