抄録
In developing smaller hydraulic and lubrication systems, it is a major and inevitable task to reduce the size of the reservoirs. With smaller size reservoirs, some problems exist such as if bubbles can efficiently be removed during the fluid sojourn in the reservoirs or if degradation of hydraulic oil or lubrication fluid can be reduced. In hydraulic systems, there are problems caused by oil entrainment of bubbles such as a faster rate of oil deterioration caused by bubble compression, rising temperature of surrounding fluid, fluid combustion and the system dynamics deterioration. As is well known, bubble removal is not easy even using a vacuum chamber. One of the authors has developed a bubble elimination device with a straight swirling flow tube. The device has the capability of eliminating bubbles and to decrease the dissolved gases. However, it is not applicable with a small flow rate. In this study, we have proposed and developed a new type bubble elimination device, which has a tapered contracting swirling flow tube. It can allow for effective swirl flow and provide for an appropriate pressure distribution in case of a small flow rate, compared with the former device. In this paper, the pressure distribution along the swirl flow tube is measured and using a measurement device to determine the amount of bubbles in a fluid, which has been recently developed, the amount of bubbles can be accurately measured before and after the use of the new bubble elimination device. The validity of the method has been verified using experiments.
