The problem of pressure ripple propagation in fluid filled pipelines has been understood for a long time. To-date, however, mathematical representations of pressure ripple standing waves generated in hydraulic systems have been limited to very simple systems operating at low mean pressure levels and over limited frequency ranges. This report details the evaluation and development of the mathematical impedance representation of hydraulic systems and system components. With the result that these can be used to predict, with confidence, pressure ripple levels in hydraulic circuits under normal conditions of operation and over a wide frequency range. The confidence comes from the detailed practical examination of the pressure ripple levels created in hydraulic systems, made up from standard hydraulic components, operated under normal conditions of pressure and flow. Although the test circuits used are only representative of practical systems, they do not perform any specific function, they incorporate all the major features of circuit design, including branch lines and impedances (components) in series. Lastly, the ability to model with accuracy the pressure ripple levels within a hydraulic circuit provides the means by which they can become part of the overall design specification for a hydraulic system. This thesis illustrates the difficulties which restrict the practical implementation of this ideal.
|Date of Award||1984|