Influence of thermo-physical properties of hydraulic fluid on axial piston pump dynamics: An experimental validation and numerical study with leakage flows and power losses

This work presents a comprehensive mathematical model to predict the thermal behavior and performance of axial piston pumps (APPs). The model simulates piston motion, flow and pressure dynamics, power losses across critical interfaces, and temperature rise due to viscous frictional heating. A novel approach of the work is the integration of temperature and pressure derived from the above simulations to calculate dynamic fluid properties, improving the accuracy of flow and pressure predictions, especially in regions prone to cavitation. It predicts outlet and case temperatures based on inlet temperature, fluid properties, and energy dissipation at steady and transient states. This study also accounts for temperature changes from fluid compression/expansion and churning losses and evaluates leakage and friction losses from clearances in sliding pairs at different operational conditions. Experimental validation has been done and the results demonstrate the model’s superior accuracy compared to previous studies. The proposed model offers a reliable tool for prototyping to designers and manufacturers of APPs, enabling better prediction and optimization of pump performance under varying operational conditions.