Simulation Study On Spray And Combustion Process Of One DME Yacht Engine

The future direction of development in marine engine technology will be low-carbon and low emission. One yacht diesel engine is studied in this paper. The main tasks were completed as follows:1. The structure of combustion chamber was properly improved based on cylinder diameter, compression ratio, fuel properties and other related factors. Besides, the three-dimensional geometric models before and after the combustion chamber improved were built.2. The dynamic mesh models were established respectively before and after the combustion chamber improved by Es-ice in LINUX system.3. The engine performance, gas flow condition, mixture formative situation, major pollutants distribution and emission characteristics were numerically calculated when the engine fueled with DME based on combustion model of turbulence-controlled eddy break-up (that is EBU model) before and after the combustion chamber improved. Besides, these calculations were compared and analyzed.4. Two performance parameters of fuel injection advance angle and swirl rate were optimally analyzed after the combustion chamber improved on the DME yacht engine. The engine performance, emission characteristics and major pollutants distribution in cylinder in different fuel injection advance angles and swirl rates when fueled with DME before and after the combustion chamber improved were numerically studied. Comparison and analysis on the results of numerical calculation, main conclusions were gained as follows:1. The later gas flows in cylinder was perfected, but also DME atomization and combustion were promoted after the combustion chamber improved. Besides, the engine power was not affected, on the contrary, the work of the engine was more gentle.2. NOX and CO₂ emissions were declined approximately 7.3626% and 2.641% respectively compared with the previous engine.3. Both NOX and CO₂ were first produced in the middle and upper part of the combustion chamber after burning, then spread to the sides gradually, and the mass fraction in center was low.4. The fuel injection advance angle and swirl rate after the combustion chamber improved on the DME engine were selected BTDC -9°CA and 5040 r/min to be ideal.Above all, these will be provided a reference basis for improving the combustion chamber and optimization performance parameters of the DME yacht engine, besides, these also have a great significance for the development of future marine engines.