低扬程泵装置原、模型和防止“有害”汽蚀参数换算  

Conversion of performance for model pump to actual pump and prevention of harmful cavitation

作　　者：周君亮[1] 

机构地区：[1]江苏省水利厅,江苏南京210029

出　　处：《排灌机械工程学报》2015年第3期185-195,共11页Journal of Drainage and Irrigation Machinery Engineering

摘　　要：依据中国泵和泵站模型水工试验作设计前期工作时,行业规定在泵水力装置模型制作中要求过流流道几何相似,但表面粗糙度与原型按一定比例相等和不重视容积损失相似,有比尺效应;在模型试验中,流道水流流态可能有部分在光滑紊流区与原型水流态不相同和允许降低原型泵转速做模型试验,有Re数效应;两者造成原、模型水力参数换算后误差很大,须用经验公式修正,各国学者已提出了十几个经验公式.提出了人工消除参数中的比尺效应和Re数效应,将模型试验成果按不等效率换算成与原型泵流道几何相似、水流流速相同、水力效率不相同的新模型,新模型成果由水工相似定律等效率换算成新模型原型水力参数,并可防止叶型"有害"汽蚀.采用该方法换算皂河第一抽水站模型试验为原型水力参数,与试运行成果符合.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 hydraulical- ly 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 measure- ment 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 model whose geometry is similar data from a model are converted into to the prototype and in which stream a new set of data for an artificial 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 1 st stage pumping station situated on River Zao from the experimental data of the counterpart mo

关 键 词：泵水力装置参数 水力损失 容积损失 机械损失 比尺效应 Re数效应 汽蚀 比转数 

分 类 号：S277.9[农业科学—农业水土工程]