摘要
浑水管道输水灌溉系统中,防泥沙淤积问题的技术措施为管道输水灌溉技术在渠灌区的推广应用提供技术支撑管。试验通过旋流器的作用产生螺旋流,以降低泥沙沉积的速度。通过试验分析了不同径高比导叶的旋流器在运动时产生的螺旋流旋流特性将圆管螺旋流看作是水泵产生外来压力的轴向Poiseuille流动和旋流器导叶强制导旋产生的周向Coutte流动,并将其流速分解为轴向流速,周向流速和径向流速。结果表明,测试断面的压力随着旋流器上导叶径高比的增加而增加;旋流器位于测试断面下游时的压力大于其位于测试断面上游时的压力;测试断面下游水流的轴向速度随导叶径高比的增加表现为先增大后减小的趋势。断面的轴向流速分布呈现类对数分布,在中心区域,即距管轴约小于2.5 cm的范围内,轴向流速较大,且相对比较均匀;在此范围以外受液体黏度影响,流速变化较快。其周向速度随导叶径高比的增加有先减小后增大的趋势,且在r1<r<r2(r1距管轴约2 cm,r2距管轴约3 cm)的主流区,周向速度具有强制涡的速度分布特征,该区域的速度值较大,水流旋转强度激烈。在r<r1,r>r2的准自由涡区,该区域速度值相对较小,尤其在管壁处,水流黏性的影响,速度最小。径向速度随导叶径高比的增加逐渐减小。同时,通过对涡量场的研究,得出了测试断面旋涡的大小和分布情况,进一步认识到流体运动的物理本质。
The technical measures of preventing silt deposition in muddy water pipeline irrigation system provide technical support for the application of pipeline irrigation technology in the canal irrigation area.. The spiral flow is produced by the action of the hydro-cyclone to reduce the deposition rate. The model test has been applied to the research to observe the spiral flow characteristics produced by guide vanes with different diameter-height ratios in hydro-cyclone. The spiral pipe flow is regarded as two parts. One is Poiseuille flow forced by pump on axial direction. Another produced by external pressure vane is circumferential Coutte flow, and the flow velocity is decomposed into axial velocity, circumferential velocity and radial velocity. It shows that the pressure of the testing section will increase if the diameter-height ratio of guide vanes gets higher, the pressure of hydro-cyclone will grow larger when it was located in the downstream of testing section than the upstream. The axial velocity in the downstream of the testing section will increase firstly but then decrease as the rise of guide vane diameter-height ratio. And the axial velocity of cross section is similar to logarithmic distribution. In the central region, that is, in the range less than 2.5 cm from the pipe axis, the axial velocity is larger and relatively uniform, which belongs to the core region of the spiral flow. In addition to this range, the flow velocity changes rapidly due to the viscosity of the liquid, which belongs to the transition zone and the bottom zone ofviscosity. The circumferential speed in the downstream of testing section would decrease firstly but then increase as the rise in guide vane diameter-height ratio. In the mainstream region of r1<r<r2( r1 is less than 2.5 cm from the pipe axis,r2 is less than 3 cm from the pipe axis),the circumferential velocity has the characteristics of the velocity distribution of the forced vortex,and the velocity of the region is larger and the rotation intensity of the flow is intense. In the quasi free vortex zone of r<r1 and r>r2,the velocity value is relatively small,especially on the pipe wall,whose circumferential velocity is the minimum. The radial velocity in the downstream of the testing section will decrease gradually with the rise in guide vane diameter-height ratio. By studying the vorticity field,the size and distribution of the vortex in the test cross section are obtained,and the physical essence of the fluid motion is further recognized.
作者
杨小妮
马娟娟
李永业
孙西欢
YANG Xiao-ni;MA Juan-juan;LI Yong-ye;SUN Xi-huan(College of Water Resources and Engineering, Taiyuan University of Technology, Taiyuan 030024,China;Polytechnic Institute, Taiyuan University of Technology, Taiyuan 030024,China;Jinzhong College,Jinzhong 030600,Shanxi Province, China)
出处
《中国农村水利水电》
北大核心
2019年第12期10-15,共6页
China Rural Water and Hydropower
基金
国家自然科学基金资助项目(51109115)
山西省自然科学基金项目(2015011067)
关键词
旋流器
水泵
压力分布
涡量场
管道
hydro-cyclone
pump
pressure distribution
vorticity
pipeline
