Frosina, Emma (2016) A CFD Approach to the Optimization of Components in Fluid Power. [Tesi di dottorato]

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Abstract

Hydraulics has the highest energy density of any power transmission technology and is a very effective way to transfer power from a source to a user. The convenience of sharing a single power source with many users with high reliability, justifies the wide use of this technology. The recent development of new components and technologies especially the use of electronic sensors and controls on hydraulic components, makes hydraulic systems more flexible and efficient. Hydraulic systems can be used in niche application where electromagnetic effects must be avoided. But hydraulics has a few disadvantage including low efficiency, high costs, noise, leaks and complexity. Hydraulic systems capability of creating high forces with small electronic control devices has found wide application, and electro hydraulic components are widely used in applications that require precise actuator control or matching of variable working conditions. Hydraulic is widely used in many sectors. In this PhD Thesis the research has been focused on the optimization of hydraulic components used in the industrial fields and on engines for lubrication circuits. In recent years, many studies were initiated to improve the performance of hydraulic components. However, the scientific understanding of valves, pumps and transmissions operation is limited because of the lack of three-dimensional fluid dynamics computation capability. In this PhD thesis a 3D computational fluid dynamics (CFD) modeling technique developed by the Hydraulic Research Group of the University of Naples Federico II led by Professor Adolfo Senatore is presented. The methodology has been applied for the study of several different applications. Using a three-dimensional CFD approach it is possible to improve component performance and the understanding of the internal flow of each component. To achieve the goals, the hydraulic research group of University of Naples “Federico II” has worked in close collaboration with the Center for Compact and Efficient Fluid Power at the University of Minnesota led by the Professor Kim A. Stelson. The first chapter describes, in detail, the three-dimensional CFD modeling methodology proposed in this thesis. After an introduction to Computational Fluid Dynamics (CFD), the methodology will be shown along with all possible applications. Then, in the second chapter, each study will be presented. Research is focused on the optimization of hydraulic components. In particular, these applications were studied: 1) Hydro - Mechanical Transmission, 2) Variable Displacement Vane pump, 3) Gerotor Pumps, 4) Engine Lubrication Circuit, 5) Pumps as Turbine (PAT), 6) Directional Spool Valve, 7) Flow Control Valve. The results demonstrate that the technique achieves high accuracy for a wide variety of applications and components.

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