Dynamics of Transmission Line Junctions - Comparison of CFD Results Against Measurements

Computational Fluid Dynamics (CFD) has become a valuable tool in the development of fluid power components due to its ability to model flows in complex geometries where simple analytical models are difficult to apply. The downside of CFD is the high computational cost of the method which prevents the application to whole fluid power systems. However, large parts of such systems can usually be modelled by more simple approaches like transmission line modelling. A coupled approach for a simple transmission line system is shown in this paper: Cylindrical parts of the flow domain are modelled with a spatially one-dimensional transmission line model augmented with frequency-dependent friction. The geometrically more complex intersections of cylindrical geometries like elbow joints and T-junctions are treated with a CFD solver in the Open-FOAM system. The simulation results from this coupled model are compared against a set of measurements from a test rig for elbow joints where cylindrical transmission line sections are connected at an angle of 90 degrees.