装备封闭式吸水罐的泵站水力学特性

针对吉林省某高扬程调水泵站进行了CFD数值计算.在网格无关性检查的基础上,采用RNG k-ε湍流模型和SIMPLEC算法,对单泵运行、2台泵和3台泵同时运行的不同工况进行计算.从水力损失、流线图、流速分布均匀度和速度加权平均角度等方面对比分析了这些工况的水力损失和内部流场的差异.研究结果表明,边机组在吸水罐内没有正对喇叭管的旋涡,对应的吸水管内流线较为光顺,未发生“S”型扭曲.对于单泵或多泵组合运行,边机组和边机组组合运行时的流速分布均匀度和速度加权平均角度最高,比中间机组和中间机组组合运行时的分别平均高1.8%,5.602°.因此,装备封闭式吸水罐的泵站,中间机组的流态较边机组恶劣,而边机组的流态反而较好.这一结论与常规开敞式泵站恰好相反.针对这类泵站,若需要单泵或者是2台泵运行时,建议优先考虑1台边机组或2台边机组组合的运行方式.

Hydraulic characteristics of pumping station equipped with closed water tank

The closed water tank is suitable for a pumping station with great variation in water level in its front. However, there are rarely few studies on flow and hydraulic characteristics in such a kind of pumping station. Thus, the flow in a high-head water pumping station in Siping city, Jilin province is simulated by CFD code. Based on a grid independence analysis, the hydraulic loss and internal flow fields are calculated by means of the RNG k-ε turbulence model and SIMPLEC algorithm when a single pump, two and three pumps are in operation, respectively. It is shown that there is no vortex below the bell mouth in the water tank, and the streamlines in the suction pipe are relatively smooth, causing the flow without "S" shaped distortion. In addition, the axial velocity distribution and velocity-weighted average swirl angle at the bell mouth are more uniform by 1.8%,5.602°when one pump or two pumps close to the side walls of the tank are in operation but the middle pump is in stop than those when the middle pump is in operation but one of two pumps near the side walls is either in stop or in operation. Hence, the flow pattern in front of two pumps close to the side walls of the closed tank is better than the middle pump, showing an opposite situation to the suction sump. For a pumping station with closed tank, if one or two pumps is/are in operation is needed, it is suggested that one pump or two pumps near the side walls should be operated in priority.