自動車用トランスミッションオイルのキャビテーション崩壊気泡の温度分布可視化計測

抄録

Cavitation occurrence has been reported in automotive transmission under certain conditions. When cavitation occurs in automotive transmissions, there is concern about the effects on the physical properties of the transmission oil due to the local transfer of heat from the cavitation bubble collapse to the transmission oil⁽¹⁾. Although there is no previous study of heat transfer to oil by cavitation bubble collapse, the details of this phenomenon are still unknown. In this study, we measured the temperature rise phenomenon caused by acoustic cavitation in the transmission oil. For the measurements, we used the non-contact visualization system to measure temperature distribution in colored oil based on the two-color LIF method⁽²⁾, which was established in our previous study. This system uses Pirromethene597 as the fluorescent particle because of its temperature dependence of the fluorescence spectrum and its ability to dissolve in oil. The excitation wavelength of Pirromethene597 is longer than that of transmission oil, so the fluorescence of the oil itself can be reduced. In addition, this system is effective for high-precision temperature measurement in colored oil because it does not require positional calibration by extracting two wavelengths from a color image taken by a single CMOS camera. As a result, we succeeded in capturing the temperature change caused by acoustic cavitation bubble collapse in transmission oil as a visualized image and the generation of a high temperature field in a small area due to the cavitation bubble collapse was observed. In addition, the feasibility of this measurement system was demonstrated.