For many hydraulic systems, fixed-displacement axial-piston pumps often employ swash plate. The design challenge for such a pump is to minimize the pressure and flow ripples and the consequent noises. Although the use of grooves at the leading and trailing sides of the pump manifolds has been adopted by several manufacturers as a remedy to this problem, theoretical modelling and analysis of the effects of these silencing grooves are very limited. This study presents a model that puts special emphasis on analysing the effect of volume variation of the silencing grooves. All the non-linear dynamic and algebraic equations developed during modelling have been solved in a Matlab/Simulink framework. The analysis has been carried out for a pump with leading-side manifolds, since experimental results for such a pump were available. Through a constant-speed parametric analysis at fixed load, optimal dimensions for these grooves have been indicated. The major contribution of the present work is the development of a mathematical model that attempts an explicit solution of pressure within each silencing groove. The model has been presented in the analysis as an effective design analysis tool for minimizing the pressure and flow ripples.

An in-line axial-piston swash-plate pump with pressure compensator is widely used for its fast speed of response and power economy. Although several simulation based design approaches exist to minimize issues like fluid-born noises, ample scope exists for more exhaustive design analysis. The most popular pressure compensator for a variable displacement pump with a spool valve actuating the control and bias cylinders has been taken up here. With an existing comprehensive flow dynamics model, an updated model for swiveling dynamics has been coupled. The dynamics also includes the force containment and friction effects on the swash plate. A design optimization has been accomplished for the pressure compensator. The target of the optimal design has been set as minimizing the transient oscillations of the swash plate, the compensator spool, pressures in the bias and control cylinders along with avoidance of both over-pressurization and cavitation in the bias cylinder. It has been found that the orifice diameters in the spring-side and at the metering port of the spool valve and in the backside of the bias cylinder have critical role in arriving at an optimum design. The study has led to a useful design procedure for a pressure compensated variable displacement pump.

Experimental and numerical analyses are carried out for a natural circulation loop (NCL) under low and moderate heater power. The effect of ambient temperature variation on the loop thermal behavior has been taken into account in present study. The effect of liquid inertia has a role in the initial transience, as revealed by the numerical and experimental observations. The steady-state results from the present analyses are validated with the reported dimensionless results for NCL. The experimental steady-state results are in fair agreement with the developed lumped numerical models. At moderate power, the numerical and experimental results indicate periodic oscillations.

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