Abstract:In China, the prophase design of a new pumping station project is based on the databases established from existing hydraulic experiments on a series of pump and pumping station models. It is regulated that the geometry of the model of a pump or pumping hydraulic installation must be similar to the geometry of its prototype. However, there is a scale effect, because the ratio of the roughness to the characteristic linear dimension of the model is not exactly equal to that of the prototype, and the volumetric efficiency of the model may not be the same as the prototype. Additionally, the hydraulically smooth regime may exist in parts of the flow passages in a model, suggesting the flow regime differs from that in the prototype. Also, it is allowed that the model pump can be tested at a lower rotational speed than the prototype pump. These two situations result in Reynolds number effect. Because of these two effects, there are signification differences in the prototype performance between the measurement and the estimate by using the affinity laws. Thus various empirical formulas have to be proposed to modify the existing affinity laws. As a result of this, ten or more formulas have been put forward over the world so far. The author proposes an approach to eliminate the scale and Reynolds number effects here. At first, the experimental data from a model are converted into a new set of data for an artificial model whose geometry is similar to the prototype and in which stream velocity and hydraulic efficiency are the same as the prototype by means of an empirical formula with variable overall efficiency. Then the new set of data are converted into the hydraulic performance parameters of the prototype by making use of the affinity laws. This approach can prevent a pump from the harmful cavitation onset on its blades. The approach has been applied to convert the hydraulic performance curve of the prototype pumps in the 1st stage pumping station situated on River Zao from the experimental data of the counterpart model pump. The predicted performance curve agrees well with the recorded one in operation.
[1]周君亮. 泵站建设中装置选用问题[J]. 排灌机械, 2001,19(1):3-12. Zhou Junliang. Selection probrems for pump station equipment[J]. Drainage and Irrigation Machinery, 2001,19(1):3-12.(in Chinese)[2]华东水利学院. 水工设计手册(第1卷):基础理论[M]. 北京: 水利电力出版社, 1983.[3]Japanese Standards Association. JIS B 8327:2002Testing Methods for performance of pump, using mode pump[S]. [S.l.]: Japanese Standards Association, 2002.[4]周君亮. 皂河第一抽水站装置性能和主机结构[J]. 江苏水利科技, 1992(2):33-46. Zhou Junliang. Device performance and the host structure of Zaohe pumping station[J]. Jiangsu Water Resources, 1992(2):33-46.(in Chinese)[5]周君亮. 原型及模型泵水力装置参数换算[J]. 排灌机械, 2009,27(5):273-280. Zhou Junliang. Study of conversion for performance of model pump to actual pump[J]. Drainage and Irrigation Machinery, 2009,27(5):273-280.(in Chinese)[6]Japan Association of Agricultural Engineering Enterprises. Pumping Station Engineering Handbook[M]. Tokyo: [s.n.], 1991:36-38.