Machining instability is influenced by threedimensional vibrations in oblique turning. There are many kinds of linear and non-linear factors contributing to the vibrations that lead the machining away from the stable status. The dynamic turning system is analytically modelled in this paper. The dynamics of turning is formulated as a function of cutting tool geometry, cutting conditions, workpiece material property and machine tools structural performance. The non-linear factors are also included in the modelling such as builtup edge (BUE) and lubricant, etc. The whole turning system is simulated by a novel model that involves linear factors and nonlinearities, as well as the structural dynamics of machine tools. The simulation can interactively simulate the complexity of the machining process in a user-friendly, effective and efficient manner.
A lumped parameter model is developed to study performance of marine diesel engine thermal management system. One dimensional flow equations combined with classical Webie combustion model and Woschni heat transfer model are employed to describe diesel's flow characteristic. Modeling results of heat release from diesel engine is validated against experimental data. Cooperated with experimental data based models of water pump and heat exchangers, thermal management system performance is analyzed while engine fresh cooling water outlet temperature is controlled to achieve a certain value by a PID temperature regulating valve. The results shown that inlet seawater temperature variation has relatively little effect on opening of regulating valve, but engine power output variation results in notably regulating valve opening fluctuation. Modeling results would be employed in an advanced submarine diesel engine system design. Index Terms-lumped parameter model, thermal management system, marine diesel engine
The scoop cooling system is widely used in advanced ships which usually requires a water inlet device protruding out of the board. The structure of the water inlet device not only determines the cooling water flow into the system, but also affects the additional resistance of the hull. The ratio of the static pressure difference between windward side of the device and the environment and the dynamic pressure head of the cooling water entering the flow channel is defined as the scoop lift head. The scoop lift head and additional resistance are used to describe the hydraulic performance of the water inlet device of the scoop cooling system, and a theoretical analysis method for the performance of the water inlet device of the scoop cooling system is proposed. The actual ship parameters are used to verify the scoop cooling capability and drag resistance characteristics of the water inlet device.
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