Shigeru Tsuji

An experimental research on water-based hydraulic fluid. (Characteristics of a fixed-delivery vane pump)

Recentlyt he social demands for energy conservation and product safety of hydraulic equipments are becoming higher and higher. Water-based fire-resistant hydraulic operating fluids are thought to fit to these demands. In this research some effects of the water contents of water-glycola nd O/W emulsion, w hich are typical water-based fire-resistant hydraulic operating fluids, on the characteristics of a fixeddelivery vane pump, made to be used mainly with the petroleum-based hydraulic operating fluids, were studied. Following are some of the results of the experimental research presented in this report. (1) Total efficiency of the test pump was found to remain unchanged practically and to be more than or equal to 70% during its test drive of 250 hours using the water-glycol having less than or equal to 80 wt% water contents. (2) Test pump damage due to abrasion etc. was hardly found during the 250 hours test drive with water-glycol having less than or equal to 70 wt% water content except for the exceeding small and temporary damage at the beginning of the test.

A Fundamental Study of Aeration in Oil : Effect of Air Diffusion on the Change in Bubble Diameter

In this paper we present the analytical and experimental results on the effect of air diffusion of a single spherical bubble in oil for both cases when pressure change as well as rotational fluid motion is present or absent. We measured the change in diameter in a case without pressure change and confirmed that an existing theory was useful when the dissolved air was initially undersaturated, if a suitable value of the air diffusivity affected by the rotational motion and the fluid temperature could be chosen. On the change in diameter in a case with pressure change, we confirmed analytically and experimentally that under a certain condition the bubbles grown under low pressure needed a long period of time to return to the initial diameter when the pressure was restored to the atmospheric one.