A study of temperature rise in oil due to compression

Abstract

Temperature rises of various oils were measured in both impact tests and quasi-adiabatic compression tests. A steel ball impacted against an oiled sapphire glass in the impact test. It was found that the maximum temperature rise was 45 °C in impact tests. A close relationship between temperature rise and α amax was found for oils of relatively low viscosity, where α was the pressure-viscosity coefficient and amax was the maximum acceleration of the hammer during impact; namely, the temperature increased with each increase in the product of the contact force and the pressure-viscosity coefficient. In the compression tests, the temperature increased almost linearly with increase in the volumetric strain regardless of the type of oil. The order of the temperature rise for the corresponding oil in each experiment was reversed; i.e. a higher temperature increase was observed for an oil of smaller pressure-viscosity coefficient in the compression test. On the contrary, a higher temperature rise was noted in the case of a larger pressure-viscosity coefficient in the impact test. As far as the temperature rise is concerned for entrapped oil in the impact tests, there exists an optimum combination of viscosity and pressure-viscosity coefficient.