田间便携式短喉槽的数值模拟

Numerical simulation of portable short-throat flume in the field

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。

Portable short-throat flume, which measuring the discharges of water inlet in the field, is a new flow- measuring device. Based on the principle of critical flow and RNG k-ε three-dimensional turbulence model, simulations of 16 working conditions by FLOW-3D software were carried out on the portable short-throat flume with 76 mm width to study hydraulic performance. The time-averaged flow field,flow regime,velocity distribution and Froude numbers were obtained and compared with measure values. The results showed that： Simulated values were consistent with the measured values within ＋ 10% errors and the measuring range of the flume was up to 40 L/s;Compared to long-throat flume, the head loss of portable short-throat flume in the field was less; Furthermore,equations of upstream depth with discharge under different working conditions were fitted by regression analyses, and the relative error was less than 9.95%. In conclusion, the portable short-throat flume in the field meets the demand for precise measurement of discharges of water inlet in the field.