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In the search for fuel efficiency and emission control in modern gasoline powered automobile engine operation, the single largest problem is the knowledge of the state of the fuel involved. That is, when the fuel is totally liquid it can be handled in much the same way as a hydraulic system. In addition, when the fuel becomes a gas it will function in a manner similar to a pneumatic system. However, in a fuel system the actual state of the fuel depends on the composition of the fuel, the operating conditions, and the ambient conditions. To the authors' knowledge, the analytical model that describes the dynamic time-based performance of a fuel system has not been successfully formulated in the past due to the lack of an adequate time-based fuel state model. This paper will present a complete model of an engine fuel system along with a computer program that is capable of producing a computerized analysis of the dynamic performance for the system.

Every hydraulic system use requires a pump to supply the necessary flow and support the imposed pressure cycle. Therefore the performance of the pump in a hydraulic system is critical to the overall performance of the system. It is a well known fact that the performance of a hydraulic pump is influenced by both the speed at which it is operating and the pressure to which it is subjected. This paper evaluates the volumetric efficiency of a hydraulic pump using both the fundamental expressions which are generally accepted and actual data test data. The widely accepted equation for pump leakage is presented along with an expression that includes the parameter of speed. Results obtained using a pressure-loaded gear pump are used to compare and evaluate the analytical expressions. This comparison reveals a significant influence of speed at high pressures on the volumetric efficiency of the pump.

The Computer Aided Analysis and Simulation (CAAS) package is the result of a multiphased program aimed at developing a user oriented, computer aided design technique for the analysis, design and specification of hydraulic power transmission systems. The package is intended to eliminate the need for detailed computer programming on the part of the system designer and allows effective use of the technique by anyone familiar with the CAAS package. This study has included the development of the general system analysis and optimization techniques, the development of the Probelm Oriented Language (POL), modeling of the most commonly used hydraulic components and testing of a selected group of hydraulic system components to verify the models developed. This paper presents the rationale of the CAAS package. The theoretical basis, program structure and application examples are included.