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为进一步研究田间便携式短喉槽过槽的水流特性及测流精度,基于临界流原理和RNGk-ε三维湍流模型,利用FLOW-3D软件对喉道宽度为76mm的田间便携式短喉槽在16种工况下的水力特性进行全流场数值计算,获得了时均流场、槽内水流流态、断面流速分布及佛汝德数,并与试验实测值进行对比分析。结果表明:1)模拟流场分布及流态与模型试验情况具有一致性,量测流量范围宽,最大可达40L/s,能够满足田间量水的流量要求;2)水深、断面流速、佛汝德数模拟值与实测值基本吻合,相对误差均小于10%;3)该短喉槽最大水头损失占总水头的12.89%,小于长喉槽最大水头损失占总水头的13%;4)通过回归分析得到了田间便携式短喉槽的上游水深-流量计算公式,其最大测流误差为9.95%,满足灌区量水精度的要求。
In order to further study the flow characteristics and accuracy of flow measurement in the field of portable short-throat tank, based on the critical flow theory and RNGk-ε three-dimensional turbulence model, FLOW-3D software was used to measure the flow field of portable short throat tank with 16 throat width The hydraulic characteristics under different operating conditions were used to calculate the full flow field. The average flow field, the flow pattern in the tank, the distribution of cross-section flow velocity and the Froude number were obtained and compared with the experimental data. The results show that: 1) The distribution of simulated flow field and the consistency between the flow regime and the model test are consistent. The measured flow range is wide, up to 40L / s, which can meet the flow requirement of field water. 2) The water depth, The relative error is less than 10%; 3) The maximum head loss of the short throat is 12.89% of the total head, less than the maximum head loss of the long throat is 13% of the total head; 4) Through the regression analysis, the formula of the upstream water depth and flow rate of the portable short throat in the field was obtained. The maximum error of flow measurement was 9.95%, which met the requirements of the precision of the water quantity in the irrigation area.