This thesis describes the design, development and testing of a distributed parameter hydraulic system simulation program based on the method of characteristics, and is intended to extend and complement the work being carried out at Bath University on the computer aided design of fluid power systems on small computers. The first part of the thesis is an extensive literature review of distributed parameter techniques and related topics, and represents a stock-taking of current simulation methods and their applicability to fluid power system modelling. The method of characteristics is a numerical technique for analysing wave propagation effects in the time domain. A general program structure was designed whereby various systems could be analysed by subroutines modelling the behaviour of individual hydraulic components linked together by pipe models based on the method of characteristics. General aspects of the program operation were tested by simulating a hydrostatic transmission, good correlation was obtained with analytical results, and with a lumped parameter simulation. More specific problems of component modelling were investigated by simulating a Barmag type, 3 port pressure compensated flow control valve. The program was applied to the analysis of pump generated pressure ripple. Good agreement was obtained with experimental results demonstrating the ability of the method of characteristics, as programmed, to accurately predict high frequency effects in hydraulic systems. The program providing an alternative tool for analysing fluid borne noise, which is especially suitable for situations where transient effects are important. 006. The method of characteristics is not ideal for general hydraulic system simulation and the recommendations for future work include a scheme for incorporating it into the existing lumped parameter simulation language (HGSP) developed at Bath University.
|Date of Award||1981|