大口径PCCP管道水力摩阻系数的实证研究OA

The hydraulic friction parameters of pipelines are among the most crucial hydraulic parameters for the operation scheduling and digital-intelligent construction of long-distance water diversion projects.For a long time,issues such as a wide variation range of recommended values and a lack of field calibration based on measured data have persisted,affecting pipe design and accurate regulation.Based on the prototype tests conducted on DN2800 and DN3200 pressure water pipelines of the Yinchuojiliao Water Diversion Project,this paper systematically studies the values and variation patterns of the Manning roughness coefficient,Hazen-Williams coefficient and equivalent rough-ness.The results indicate that the pipeline roughness coefficient decreases with increasing flow velocity and increases with increasing pipe diameter,showing a positive correlation with flow velocity to the power of-0.1.When a constant roughness coefficient is used,the calculation error for head loss can range from 10%to 20%.The measured Hazen-Williams coefficient ranges from 145 to 150,which is greater than the recommended values in most specifications.Assuming a constant Hazen-Williams coefficient can lead to a calculation error of 5%to 10%in head loss.The equivalent roughness of PCCP pipelines with cement mortar-lining should be taken as 0.05 mm.When the equivalent roughness is reduced from 0.05 to 0.01 mm for the velocity of 1.5 m/s,the roughness coefficients of DN2800 and DN3200 pipelines decrease from 0.1071 to 0.010 34 and from 0.010 83 to 0.010 46,respectively,representing reductions of 3.45%and 3.42%.This indicates that the roughness coefficient of 0.009 or lower cannot be achieved.