在屏蔽泵电机中,定转子屏蔽套之间存在薄环域水,当定转子发生相对位移时,薄环域水的受迫移动时,会对定转子产生非常重要的反作用影响。在R. J. Fritz论文中,研究了环域水对于长轴的影响。但在FRITZ公式中,环域水的水动力质量mH的影响是基于环域长度是无限长的,而忽略了端部泄露量的影响,公式中的L简单地认为是环域的长度。但是转子都是有限长度的,公式中需要考虑端部泄漏量的影响。所以,在计算环域水的水动力质量时,考虑了端部泄漏量,得到环域的有效长度L有效。In the canned motor pump, fluid is contained in the thin annular regions between the rotor and stator in locations such as the can annulus and in seals. When relative motion takes place between rotor and stator, the constrained motion of the fluid can give rise to significant interaction effects. In a paper authored by R. J. Fritz, the effects of an annular fluid on the vibrations of a long rotor are investigated. The hydraulic mass term mH as defined in Fritz’s equations, is based on the as-sumption that the annular region is sufficiently long that end leakage effects are negligible. For this case, the length L is simply the actual length of fluid annulus being considered. But the rotor is always finite length;the influence of the length needs to be considered in the formula of mH. Therefore, the effects of fluid leakage at the end of the annular region can be taken into account by modifying the length L to get the effect length Leff.
