Abstract
Air bubbles in hydraulic oil lower the efficiency of hydraulic systems and contribute to instrument malfunctions. To mitigate these problems, it is possible to use an active “bubble eliminator” that uses swirl flow to remove air bubbles. This study aims to optimize the shape parameters of the device. For this purpose, its performance needs to be evaluated precisely. To evaluate the performance of the bubble eliminator, we should consider a correlation between the effect of swirl flow and axial flow because these flows affect the bubble behavior in the device greatly. In this paper, we perform the experimental flow visualization and numerical simulation with different values of the diameter of the outlet and vent port. Additionally, this paper presents a new performance index named “spiral number” and evaluates the performance of the bubble eliminator using this index. This index considers the correlation between the effect of the swirl flow and axial flow. We analyze the experimental and numerical results using this index, and show that the index is useful for evaluating the performance of the bubble eliminator. We conclude that the diameter of the outlet port and vent port can be selected using this index.
