梯拱形渠道流速横向分布规律及流量量测

新疆吐鲁番地区地理及径流、泥沙条件独特,干支渠一般都采用梯拱形断面型式.通过对该地区主要干支渠流量系统观测资料的统计分析,借助二元明渠紊流掺长理论,建立了梯拱形渠道流速横向分布公式.大量不同梯拱形渠道、不同流量的流速实测数据分析和验证表明,理论与实测流速横向分布都符合对数分布规律,利用多变量回归分析,确定了流速横向分布系数a、b值.在此基础上,推导出梯拱形明渠断面平均流速计算公式,计算值与实测值误差较小,并给出了修正系数的确定方法.根据提出的明渠流速公式,进一步建立了灌区渠系中流量连续测量的实用方法和工作流程,简化了明渠测流工作,降低了量测成本,提高了测流精度.

Law of lateral velocity distribution in trapezium-arch channel and discharge measurement

Because of the unique topographic,river runoff and sediment conditions in Xinjiang Turpan area,the section with trapezium-arch shape are usually adopted in general channels and branch channels.Through statistical analysis of measured data system of discharge in the Turpan channels,and using the turbulence mixing length theory of 2-D channel,a lateral velocity distribution formula of trapezium-arch channels is established.Based on analysis and certification of a large number of measured data of different channels and different discharges,it is shown that weather theoretical form or measureds results of lateral velocity distribution are consistent with the laws of logarithmic distribution.And the lateral profile coefficients a and b are determined by the multivariate regression analysis.On this basis,the mean velocity formula in the trapezium-arch channel is deduced;the error value between calculation and measurement is little;the method for determining correction factor is given.By using the formula of the lateral velocity distribution,the measurement methods and working program of continuous discharge in the irrigation channels are established.There are good practical value in simplification in channel measurement and reeducation in the measurement cost and improving accuracy of flow measurement.