Experimrntal Study Of The Effet Of Combution System Parameters On Marine Mid-Speed Diesel Engine Performance

With the development of shipping industry and the possessing capacity of ship is increasing, the proportion of pollutant emission is increasing continually. The governments of world and International Maritime Organization (IMO) concentrate on the pollutant emission of marine diesel engine. The optimization process is conducted on a turbocharged marine mid-speed diesel engine. We study the cylinder combustion parameters of marine diesel which influences on the performance parameters, combustion characteristics and emission characteristics by experiment and one-dimensional calculation of AVL-boost. Further, we optimize the combustion system by one-dimensional calculation of AVL-boost and verify by experiment.Firstly, we study the valve train system of marine diesel engine which influences on the engine cylinder combustion properties by one-dimensional calculation of AVL-boost. Simultaneously, we optimize it by the Latin Hypercube Sampling design of experimentation. To further optimize the engine performance parameters, such as the smoke emissions, specific fuel consumption and exhaust temperature, we experiment with different turbocharger matched program and the best turbocharger is selected. Experimental investigation is performed on exhaust gas turbocharger. The effects of different intake air mass flow and turbine inlet temperature and soot are studied, and the best turbocharger is selected. Experimental investigation is also performed on cylinder heads with different intake swirl ratios, and the effect of intake swirl on marine mid-speed diesel engine performance is studied. We select the intake swirl ratio of 1.1 as the optimized. Experimental investigation is also performed on combustion chambers. Three combustion chambers with the different geometry parameters are designed. The spray distance is calculated, the spray distance and combustion chambers is optimized. The effect of combustion chamber geometry on BSFC, turbine inlet temperature and soot is studied. The best scheme of combustion chamber is selected as the optimized. Experimental investigation is performed on different performance parameter of nozzle. The effects of different holes, spray cone angle, flow and nozzle tip penetrate of nozzle on marine mid-speed engine performance are studied. The best scheme of nozzle is selected as the optimized.After the optimization process, the final scheme for a mid speed diesel engine for marine is:cylinder head with the intake swirl ratio of 1.1, SJ170Y-S6 turbocharger, scheme 1 camshaft, scheme B combustion chamber and scheme 4 nozzle. Experimental investigation indicates that, with the fuel supply advance angle at 13℃A the NOX emission meets the Revised MARPOL73/78 Annex VI in 2008, and Annex VI-Regulations for the prevention of air pollution form ships. The turbine inlet temperature, fuel consumption and soot is much lower than original engine on middle and high speed. The economy speed is 700r/min-900r/min, and the minimum fuel consumption is 190.9 g/(kW·h).