Numerical Simulation On Combustion Process Of Spark-Ignition Methanol Engline And Parameter Optimization Of Combuation Chamber

In a variety of alternative fuels in internal combustion engine, the application and research of methanolfuel are widely considered to have a good prospect. At the same time, with the development of computertechnology, multi-dimensional numerical simulation is playing an increasingly important role on the researchof work process in internal combustion engine. Through multi-dimensional numerical simulation, we can getsome more information, which we can't get in the experiment.In this paper, the research on numerical simulation of a spark ignition methanol engine was performedwith AVL FIRE software. The calculation started with the intake valve opening and ended with the exhaustvalve opening. Firstly, established the CAD geometry model of methanol engine by three-dimensional drawingsoftware named UG, and then imported it to FIRE software. In the FIRE software, the moving mesh includingintake port, intake valve and piston were generated by the use of moving mesh generation tool, established themathematical model and validated with experiment. Then the simulation results was analyzed, includingvelocity field and turbulent kinetic energy field during intake and compress process, the distribution of flamepropagation contour, flame velocity field, temperature field and NOx in the combustion chamber after ignition.In addition, for three bowl-type combustion chambers with different shapes: straight port combustionchamber, reduced port combustion chamber and exposure port combustion chamber. The calculation modelwas established separately and started to calculation. In different shapes of combustion chamber, gas flow andsize of turbulence intensity, flame propagation speed, the rate of heat release, cylinder combustion pressure,the rate of pressure rise, cylinder temperature and NOx emission were detailed analysis. Considering the engineperformance and the process of craftwork, etc., ultimately the author determined the bowl-type combustionchamber with straight port is more reasonable. In the straight port combustion chamber, the spark plug was setin the three different positions, cylinder center, departure cylinder center which was the original fuel injectorposition of the diesel engine, far from the cylinder center. The influence of the spark plug location on the combustion process of methanol engine was simulated and researched. The results showed that the spark plugcloser to the cylinder center, the spread of flame to the surrounding was more fast, and the total combustionduration was shortened. However, considering the production process of succession, the spark plug was stilllocated at the position of the fuel injector position of the original diesel.