泵与泵装置特性预测

Performance prediction for pump and pumping system

根据泵和泵站的有关文献及作者提出的泵与泵装置性能(效率及临界汽蚀余量)的表达、换算方法,通过进一步的数学推演,提出了水泵及泵装置性能统一表达式.统一表达式包括:扬程通用式、流量通用式、效率通用式、临界汽蚀余量通用式等.用二次多项式表达了泵及泵装置的扬程特性;根据最小二乘法原理给出了扬程系数计算式.介绍了总效率的表达式,并给出效率常数计算方法.介绍了计及冲击损失的影响,并适用于任意工况点的汽蚀特性表达式;同时给出汽蚀余量系数的计算方法.扬程通用式、流量通用式、效率通用式、汽蚀余量通用式等是在各表达式基础上,根据原模型泵及流道内流动相似,运用水泵相似律、比例律,推导扬程系数、效率常数、汽蚀余量系数的相似关系式;综合各表达式和系数、常数相似关系式即为既适用于模型亦适用于原型的统一表达式,或称通用式.统一表达式既可用于计算,亦可用于原模型的相似换算.

Based on the existing formulas and those proposed by the author for pump and pumping system performance （ efficiency and NPSH ） conversion, a further mathematical derivation was introduced and a group of universal conversion formula was developed in the paper. The universal formulas were applicable for head, flow rate, efficiency and NPSHe. The head curves of both pump and pumping system were presented in a quadratic polynomial, and the head coefficients were calculated by using the least square method. The overall efficiency formula was detailed and the method for determining the constant involved the formula was introduced. Also, a universal NPSH, formula, which is applicable to any operating points, and where the shock loss effect is include, was provided in this paper. The approach for determining the coefficient in that formula was proposed as well. The universal formulas for head, flow rate, efficiency and NPSHe were derived according to flow similarity in pumps and by means of the affinity laws of pump, and presented with head coefficient, efficiency constant and NPSHe coefficient. All the formulas, their coefficients and constants were integrated into one formula, respectively; thus they were considered as universal ones, which are applicable to both model and prototype pumps. The universal formulas can be used to estimate pump and pumping system performance and carry out performance conversion from model to prototype.