管道内污水两相流的阻力计算

目前的污水管道设计是将污水在管道内的流动视为单相均匀流，主要用谢才(Chezy)公式进行水力计算。由于存在管线长、流量大以及区域地形变化幅度较大等因素，建设区域排水系统需要采用新的方法，以便较准确的计算水头损失。文中将污水视为液-固两相流体。对于沿程阻力的计算，将流体分为均质流与非均质流，分别给出沿程阻力系数的计算公式；对于局部阻力，则借用气-固两相流动的局部阻力系数计算公式。最后得出了两相流情况下与单相流情况下的阻力系数区别。结论是沿程阻力系数的区别可不计，局部阻力系数差别较大，在进行设计时必须考虑。

Calculaton of the Drag Force of Sewage Flowing as Two-phase Fluid in Pipe

Sewage pipe flow is hypothesized as a single-plase unifrom flow,used to applying the Chezy formula for designing sewage systems. But now it's urgent to adopt new methods for calculating the head loss of regional drainage due to some factors, such as a long pipeline, a large quantity of flow and a great change in topography. Sewage is regarded as a liquid-solid two-phase fluid. For the convenience to calculating the linear loss, the formulas of the resistance number of even and uneven flow were given; for local resistance, the formulas were given according to the knowledge of gas-solid two-phase flow. The distinction as to drag coefficients between the two-phase flow and the single-phase flow was calculated as a result. The conclusion is that the distinction of linear resistance can be ignored, but the distinction of local resistance is relatively obvious, so it should be taken into account in the course of design.