Mathematical modeling of changing of dynamic viscosity, as a function of temperature and pressure, of mineral oils for hydraulic systems

Viscosity is the most important characteristic of hydraulic fluid. The value and changing of viscosity have essential significance for all events in the hydraulic system. The viscosity of hydraulic fluid is changed with temperature, pressure and rate of shear. However, in analyzing the hydraulic system operation it is usual to use only temperature dependence of viscosity, while influence of pressure and shear rate are neglected. In this paper a mathematical model of changing the dynamic viscosity of mineral hydraulic oil (type HM and HV) with changing of temperature and pressure is given. It is proved that pressure dependence of viscosity cannot be neglected in an analysis of hydraulic system.