考虑粗糙度影响的水泵原模型效率换算

Efficiency conversion methods for prototypes and models of water pumps considering influence of surface roughness

在分析基于水力光滑区Blasius摩擦系数的原模型效率换算莫迪方法的基础上,采用适用于"过渡区"流动摩擦系数的Haaland和Swamee-Jain计算公式,参考莫迪拓展公式处理与雷诺数有关及无关的两种水力损失的方法,提出了考虑粗糙度影响的原模型效率换算的计算式,并进行了不同"过渡区"流动摩擦系数表达式、不同类型水力损失比例的计算研究,与日本工业标准JISB8327—2002《泵性能的模型试验方法》进行了比较.结果表明:在标准规定的原型粗糙度0.025mm以内,效率换算差值不大于0.0025;所提出的计算式具有符合流动区域特征、物理意义清晰明了、计算过程简单方便、换算精度高的特点,可满足考虑粗糙度影响的原模型效率换算要求.

Based on analysis of the Moody formula for efficiency conversion of prototypes and models by means of the Blasius friction coefficient in hydraulically smooth zones,the efficiency conversion formulas for prototypes and models of water pumps considering the influence of surface roughness were proposed by adopting Haaland and Swamee-Jain formulas suitable for the friction coefficient of the transition zone and referring to the method of the Moody extension formula to treat two kinds of hydraulic losses concerning the Reynolds number. Different formulas for the friction coefficient of the transition zone as well as the proportion of various hydraulic losses,the Haaland fomula and the Swamee-Jain formula,were used for calculation and compared with those described in the Japanese industry standards JIS B 8327-2002. The results indicate that,within a range of prototype roughness 0.025 mm as defined by the standards,the difference in efficiency conversion is not larger than 0.002 5. The proposed formulas correspond in terms of the characteristics of flowing zones,clear physical significance,simple computation process,and high conversion precision. The efficiency conversion requirements of prototypes and models of water pumps considering influences of the surface roughness can be satisfied.