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Abstract
The diesel engine pro’ ides the prime mover br the majority of ship propulsion systems because of its operational reliability and economy. Lloyds Register (LR) has an ongoing commitment to the Lle\elopment of improved methods of analysis in those areas of concern to ship owners and operators. ‘Ihese include operation with variable fUels, fault condition diagnosis, condition and performance monitoring, performance optimization, and matching of propulsion system cciinponenrs. One of the methods used by LR in pursuit of the above objectives is the development and use ol advanced computer simulation techniques. These involve the modeling of complex structures with lnite element packages or the thermo-fluid modeling of the various processes in diesel engines such as: pressure charging, fuel injection, combustion, heat transfer and so on. The thermo— Ii uid models are used to provide boundary conditions for the finite element niodels or, more directly, for the prediction of engine power output and fuel consump on. These models find application in the prediction of component temperatures and thermal stresses. The objective of this thesis is to give an overview of these thermo-fluid modeling capabilities in the field of diesel engine design and provides a model that represents performance assessment for the slow speed two stroke diesel engine.
Modeling techniques and assumptions for the complete two stroke uniflow diesel engine cycle based on thermodynamics are discussed in detail. The simulation is constructed based on the mass and energy conservation principles, the scavenge period is analyzed using the isothermal t o-zone model of Benson and Brandham hich correlates with experiments on The Queens University of l3elfast and the combustion process is analyzed using two-zone combustion model. A comparison of’ the obtained simulated engine performance with the available experimental daia is presented and showed a good agreement.
The present model can be used to simulate various engines. This enables the user to optimize his engine performance without making any major repairs.