Investigations on fluid dynamics of hydraulic accumulators

Abstract

In state of the art hydrostatic installations accumulators of various designs are implemented to enhance the efficiency or to affect the dynamics of the hydraulic system. The advantages offered by the application of these devices are well known and their thermodynamic properties have been described well in the past. Yet the optimization of their particular performance re-garding fluid dynamics is an existing problem because of the lack of experimental and analytical investigation devices. Whilst operating hydraulic accumulators high dynamic flow rates and velocities including steep pressure gradients are oc-curring so that a special technique had to be created to detect these values. In the Fluid Power Laboratory of Trier University of Ap-plied Sciences a new self developed accumulator test rig re-cently was installed to measure the operating parameters of hy-draulic accumulators with the required high dynamic and accuracy. Special test procedures could be implemented to evaluate and improve especially the performance of the accu-mulators internal flow control valves. The experimental investigations were accompanied by modelling a hydraulic accumulator in a Computational Fluid Dynamic CFD environment where its internal flow phenomena could be simulated successfully. This presentation introduces the new test rig, the developed measuring procedures and the simulation model. Results of high dynamic flow and pressure measurements as well as flow simulations of hydraulic accumulators are shown.