宽浅式梯形渠道流速分布规律及流量计算方法研究

Study on Flow Velocity Distribution Law and Flow Calculation Method of Wide Shallow Trapezoidal Channel

为研究宽浅式梯形明渠流速分布规律,简化渠道流量测量过程、提高测流精度、促进灌区工作效率提升,利用声学多普勒剖面流速仪进行流速、流量、断面面积的测定;通过正交距离回归算法对相对流速和相对水深与二次抛物线函数拟合,得到垂向流速分布规律,根据横向流速分布规律结合测量数据,利用线性拟合分析得到横向流速分布影响系数,最终通过待定系数法得到断面平均流速与中垂线表面流速的系数值。结果表明:测点实际流速与平均流速之比作为相对流速,拟合得到的宽浅式梯形渠道断面流速分布规律R2均在0.937以上,拥有较好的相关性;宽浅式梯形渠道测线平均流速横向流速分布符合乘幂函数分布形式,并对横向流速流速分布公式进行流速验证,在横向相对位置0.2<(B-2 d)/B<1区间内误差均小于5%;推导出了宽浅式梯形渠道中垂线表面流速与断面平均流速关系,对AB两地宽浅式梯形渠道干渠进行断面流量验证,实测流量与计算流量的误差小于5%,符合量水规范的要求,可实际用于灌区量水。

Studying the velocity distribution law of wide shallow trapezoidal open channel can simplify the flow measurement process,improve the accuracy of flow measurement,and promote the work efficiency of irrigation area.In this paper,the velocity,discharge and section area were measured by acoustic Doppler profile current meter.The orthogonal distance regression algorithm was used to fit the relative velocity and the relative water depth to the quadratic parabola function.The influence coefficient formula of vertical velocity distribution in wide and shallow trapezoidal channel was obtained by linear fitting.The distribution law of transverse velocity was summarized and combined with the measured data,the range of influence coefficient of transverse velocity distribution was obtained by linear fitting,and its exact coefficient was determined by comparing multiple sets of data.By undetermined coefficient method,the coefficients of average velocity of cross-section and velocity of perpendicular surface were obtained.Taking the ratio of the actual velocity to the average velocity as the relative velocity,the R2 values of the fitting velocity distribution law of the wide and shallow trapezoidal channel section were all above 0.937,showing a good correlation.The average velocity distribution of the measured line in the wide shallow trapezoidal channel conforms to the power function distribution.The influence coefficient of transverse velocity in wide shallow trapezoidal channel was obtained and the velocity distribution formula of transverse velocity was verified.In transverse relative position of the range of 0.2<(B-2 d)/B<1,the error was less than 5%.The relationship between the surface velocity of the vertical line and the average velocity of the section in the wide shallow trapezoidal channel was derived.The section flow of the main channel in the wide shallow trapezoidal channel AB was verified.The error between the measured flow and the calculated flow was less than 5%,which met the requirements of the water measurement standards and could be used for water measurement in irrigation area.