| In the process of development of irrigation facilities constantly,U-shaped channel can significantly improve the utilization coefficient of canal water and utilization,and has good impermeability and frost resistance performance,It is of great significance to improve irrigating conditions and promoting water saving in irrigation district.However,in the course of its application,the standardization of irrigation and high-precision quantitative water is a major problem.At present,there are few water supply facilities in irrigation area below the canal,and the water scattered to the farmers is difficult to measure.Therefore,it is particularly necessary to develop a water measuring device with low cost,simple application and accurate measurement.This paper is based on the major scientific and technological project of Shanxi Provincial Water Resources Department in 12 th Five-Year plan."Irrigation channel system,quantity,water facility rate and shape design" in Shanxi province".This paper analyzes the problems which existing in the water quality of the final channel in the irrigation area,and it combines the standard characteristics of U-shaped channel in Shanxi Province,developed a plate flow measuring device,which used to measure the U-shaped channel within the water flow.Based on the comprehensive analysis of U-shaped channel flow measurement method research at home and abroad,on the basis of the combination of theoretical analysis,experimental research and numerical simulation method of standard U-shaped channel plate flow performance of the flow measuring device and its hydraulic characteristics were studied.The main conclusions are as follows:This paper analyzes the problems which existing in the water quality of the final channel in the irrigation area,(1)Aiming at the problems of final channel in the irrigation area and combining the standard characteristics of U-shaped channel in Shanxi Province,plate flow measuring device is developed.The flow measuring device has the characteristics of simple structure,convenient operation,strong adaptability,convenient to carry,higher accuracy of measurement and simple flow calculation formula and has great significance for the water saving and sustainable development in Shanxi area of irrigation.(2)Based on the method of momentum theorem and moment balance,the principle of flow measurement of plate flow measurement device is analyzed.Through the dimensional analysis,the plate flow measuring device under various factors is obtained,and the measurement flow is calculated as Q(28)Kg~12(Lsinq)2~5.(3)The flow performance is researched by the experiment,and obtained under the same channel slope plate flow measurement of water flow measuring device and the relationship between Angle of measuring Angle plate is positively related to exponential distribution relations,the empirical formula form for Q=ksin2.5?;At the same time,the relationship between flow flow rate and Angle plate Angle of plate flow measuring device under different slope is obtained,and the empirical formula is Q= ksin2.5?ic.(4)Through the experiment,the flow velocity characteristics of the upstream and downstream channel flow in the vicinity of the flow measuring device during the flow measurement is studied.It is found that the plate flow measuring device has less influence on the velocity distribution of the channel upstream.The flow velocity distribution of each section is centered on the vertical line of the channel.The closer the velocity of the vertical line and the flow rate is higher.Besides,none of the maximum flow rate is at the free surface,but at a position below the surface of the water,(0.6 times the water depth position)downstream of the device is lower than the maximum velocity position(0.8 times the water depth position)located upstream of the plate flow measuring device.Through the experimental and theoretical analysis,it is found that the parabolic formula is suitable calculation formula of vertical velocity and transverse velocity distribution in each cross section of flow measurement in plate flow measuring device.(5)The flow velocity and water level of the flow in the channel during the flow measurement of the U-shaped channel plate flow measuring device were simulated,it was found that the flow horizontal velocity of the upstream and downstream sections of the U-shaped channel plate flow measuring device has always been reduced from the channel center to the channel wall.The flow vertical velocity of the upstream and downstream sections center have shown a trend of increasing first and then decreasing with the increase of the water level.The maxmium sphere of influence of the plate flow measuring device on the flow in the channel was analyzed between from the plate flow measuring device upstream 0.75 m to the plate flow measuring device downstream 1.24 m.(6)The simulation of the flow along the flow in the channel during the measurement of the U-shaped channel plate flow measuring device under different working conditions was carried out,found in any channel slope and flow conditions,U-shaped channel along the water level elevation are gradually decreasing trend.The same slope channel case,with the increase in traffic,the upstream and downstream waterline changes gradually increased.(7)The numerical simulation of U-shaped channel surface elevation,water height —flow relation,flow angle relation and experimental results were compared and analyzed,it was found that the numerical simulation results are in good agreement with the experimental results.Therefore,it is feasible to use the numerical simulation method to analyze the hydraulic characteristics of the upstream and downstream section of the U-shaped channel plate flow measuring device.The simulation method has important reference value for optimizing the structure of the plate flow measuring device.The research results of this paper provide the theoretical basis for the popularization and application of U-shaped channel slab flow measuring device... |
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