摘要
长距离有压输水工程一般通过设置阻力环的水头损失替代法进行整体模型试验研究。依托深圳市北坑水库输水隧洞工程,对不同雷诺数、环数和布置方式下阻力环的水头损失替代效果及其变化规律进行数值模拟研究发现:当雷诺数Re>0.32×10^(5)后,几乎不会造成阻力环局部水头损失系数与阻力环后旋涡区长度变化;孔径比d/D减小或距径比L/D增大会增强阻力环的水头损失替代效果;当d/D=0.8,L/D=0.5,环数n>2时,阻力环平均局部水头损失系数K_(d)随环数n增加而减小,当环数n>20后K_(d)不再随环数变化。在此基础上推导出环数影响系数ε随环数n的变化规律及其拟合曲线,以及阻力替代段总局部水头损失和替代管道长度计算公式。通过分析环数对漩涡区长度的影响,阻力替代段后需设置不小于2.5D的过渡段才能保证水流流态恢复至未替代状态。
The head loss substitution method with setting resistance rings is adopted in general physical model of long distance pressurized water diversion projects.Based on the hydraulic model test of Shenzhen Beikeng reservoir water diversion tunnel project,the head loss substitution effect and its variation law of the resistance ring under different Reynolds number,ring numbers and arrangements show:If Reynolds number(Re)is bigger than 0.32×10^(5),it has less influence on local coefficient of head loss of the resistance ring and length of vortex region behind resistance ring;the decrease of parameter d/D(the diameter ratio of orifice and pipe)and the increase of the parameter L/D(the ratio of distance between rings and diameter of pipe)will enhance the head loss substitution effect;if parameter d/D is 0.8,L/D is 0.5,and the number of rings n is bigger than 2,the average local head loss coefficient K_(d) decreases with the increase of parameter n,and K_(d) does not change with the number of rings if the parameter n is bigger than 20.On this basis,the fitting curve between the ring number influence coefficientεand the ring number n,the formulas of the total local head loss in the resistance substitution section and the length of the substitution pipe is derived.By analyzing the influence of different ring number on the length of vortex region,the length of transition section no less than 2.5D should be set behind the resistance substitution section to ensure the flow pattern returns to the unsubstituted state.
作者
丁刚
李志
邹德兵
DING Gang;LI Zhi;ZOU De-bing(Changjiang Institute of Survey,Planning,Design and Research Co.Ltd,Wuhan 430010,Hubei Province,China;State Key Laboratory of Water Resources Engineering and Management,Wuhan University,Wuhan 430072,Hubei Province,China)
出处
《中国农村水利水电》
北大核心
2024年第5期41-46,共6页
China Rural Water and Hydropower
基金
国家自然科学基金(50809052)。
关键词
有压输水管道
阻力环
水头损失替代
模型试验
pressurized water pipeline
resistance ring
head loss substitution
model test
