管段沿线流量简化前后水头和流行时间差异性分析

Difference Analysis of Water Head and Travel Time Before and After Simplification of Flow Along Link

摘要:

给水管网管段沿线流量简化处理常采用水力等效方式或流量等分方式，将沿线流量分配到管段的上端节点和下端节点，以减少给水管网建模和计算的工作量。为从理论上说明给水管网管段沿线流量简化处理后带来的影响，首先分析了一般管段沿线流量简化处理前后的水头和流行时间差异性，其次分析了沿线均匀出流简化处理前后的水头和流行时间差异性。案例计算结果表明，水力等效简化处理保证了管段上端节点和下端节点处的水头与简化处理前是相同的，而简化前后管段内部各点的水头通常存在差异性；管段沿线均匀出流经水力等效简化处理后，上端节点流量分配比与管段内部出流点个数和沿线流量占比相关，而与管段直径、上端节点水头、管段进流量、管段长度和管段摩阻系数无关，使得该简化处理方法适用于上端节点水头或管段进流量具有变化性的延时模拟模型；沿线均匀出流按照水力等效方式（或流量等分方式）的处理，适用于沿线流量占比较小（距离水厂较近）的管段沿线流量简化。

Abstract:

In order to reduce the workload of modeling and calculation of water distribution systems， the hydraulic equivalent method or flow equal division method is often used to simplify the flow along the link， which distributes the flow along the link to the upper and lower nodes of the link. In order to explain theoretically the influence of simplification of the flow along the link， the differences of water head and traveling time before and after simplification of the general flow along link were analyzed， and the differences of water head and traveling time before and after simplification of the uniform flow along the link were analyzed. These two aspects were calculated and discussed in combination with cases. It is concluded that the hydraulic equivalent simplification ensures that the water head at the upper and lower nodes of the link is the same as that before the simplification， while the water head at each point in the link before and after the simplification is usually different. After hydraulic equivalent simplification， the flow distribution ratio of the upper node is related to the number of demand points in the link and the flow proportion along the link， but has nothing to do with the diameter， the upper node head， the inlet flow， the length and the friction coefficient of the link， The simplification method is suitable for the extend period simulation model with variable water head at the upper node or link inlet flow. The uniform discharge along the link is treated according to the hydraulic equivalent method （or flow equal division method）， which is suitable for simplifying the flow along the link where the internal flow along the link accounts for a small proportion （the links close to the water treatment plant）.