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MONOGRAPH 28

Impact of gas accumulator parameters on the amounts characterizing the pressure change in annular compartment of the hydraulic leg

Stanisław Szweda, Krzysztof Mazurek

Use of finite elements method and finite volumes as the tools aiding a designing process of gas accumulator and its testing as regards a determination of the impact of the parameters like: initial gas pressure, initial volume of accumulator chamber and mass of accumulator’s piston on the parameters that characterize time process of the working medium pressure i.e. maximal pressure of working medium in annular area of the leg, its increase rate and leg yield, was the project objective.

Realization of the project required a computer simulation of impact of dynamic loads to the hydraulic leg with the gas accumulator installed in it. Problem of model discretization, definition of initial conditions, especially initial load of the hydraulic leg, formulation of boundary conditions, especially the coupling surface between a solid and liquid as well as definition of external load acting on the discussed model were included in a process of development of FEM models used in the simulations.

Verification of obtained models was carried out on the basis of the results from tests of the hydraulic legs conducted in the test rig with a dynamic load generator. Verification of conformity of the FEM model of leg with gas accumulator and the standard leg with the real objects consisted in comparison of physical amounts measured during stand tests with the amounts determined numerically. External load that acts on the leg set in a test rig was modelled using the measurements of displacements of dynamic load generator piston.

The FEM models, verified experimentally, were used to analysis of sensitivity of the parameters, which characterize the leg response, for the technical parameters characterizing the gas accumulator.

Analysis of sensitivity enables the presentation of the proposal for methodology of selection the technical parameters of gas accumulator.