Theory of hydrodynamic stability for capillary pumped loops

Abstract

The oscillation of pressure drop measured across the capillary pump of a Capillary Pumped Loop (CPL) had been observed in various systems of different sizes. In the past, it was believed that the pressure oscillation had no adverse effects on the system operation. In recent tests, however, some of the performance anomalies were attributed to the pressure oscillation especially when its amplitude became larger than the limit of the capillary pump wick. The theory presented herein is intended to study the cause of the pressure oscillation and also to examine the effects of different CPL component designs on system performance. The development of the CPL hydrodynamic equations was inspired by the similarity between the fluid flow dynamics in the CPL and a spring-mass-dashpot dynamical system. The test results showed excellent agreement with theoretical predictions.