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In this paper we describe the application of a CFD methodology to characterize the orifice flows over a wide range of flow conditions with various geometrical features commonly found in hydraulic control systems. There are three objectives in carrying out this study. First, apply CFD analyses to provide physical insight into the orifice flow physics and clarify the use of relevant engineering parameters critical to hydraulic control applications. Second, quantify orifice discharge coefficient with respect to orifice diameter ratio, cross-sectional shape, plate thickness, orifice entrance and exit geometries. Third, support physical test and establish building block elements for hydraulic system modeling. The results obtained from CFD calculations agree very well with available data published in professional handbooks and fluid mechanics related textbooks, especially in the high Reynolds number flow regime.

A three-dimensional CFD methodology has been developed and applied to predict the pump performance, to understand pump flow dynamics, and to investigate pump flow/pressure ripple for gerotor pumps equipped in automatic transmission systems. The methodology is based on the commercial code CFD-ACE+ and the analytical focuses are the flow cavitation and pressure ripples over a wide range of engine speeds, 500rpm to 6,000rpm. The CFD results are first compared with the hardware measurements and a very good agreement has been achieved. Extensive CFD simulations are then conducted to study the effects of the inlet pressure, tip clearance, porting and the metering groove geometry on pump flow performance and pressure ripples.