A Numerical Approach to the Hydraulic Fluid Properties Prediction

This paper presents a numerica! approach tailored for the prediction ofhydraulic fluids physical and thennodynarnic properties, starting from a limited number of information about fluid viscosity and fluid density. Firstly, the review of some experimental based prediction models available in literature for the fluid viscosity variations is presented, and the more accurate ones for the analysis ofindustrial and automotive hydraulic fluids (mineral oils, lubricants and fuels) are selected. Then, the paper highlights the step of a possible procedure able to defme thevariations both of other physical fluid praperties (such as the isothermal or the isentropic bulk modulus, the constant pressure or the constant volume specific heat, the constant pressure, orthe constant volume, volume expansion coefficient), and of the main thermodynamic fluid properties (such as the specific entropy, the specific enthalpy and the specific internal energy).Finally, the resu1ts coming from the numerical approach previously outlined are compared with experimental data, found in literature for different mineral oils, in a range of temperature from O to 160°C and of pressure from O to 600 bar.