Abstract：In order to study the effect of the combustion chamber structure on the incylinder gas flow in a methanol engine, the effects of the original necked piston and the optimized shallow basin piston on the performance of methanol engines are compared and analyzed by means of 3D simulation calculation and engine bench test. The results show that the bench test results are in good agreement with the calculation and analysis results of turbulent kinetic energy in the cylinder. The tumble flow scale of optimized piston is significantly larger than that of the original piston, and the tumble flow in the cylinder can be fully developed. This could help the formation of mixture and the increase of turbulent kinetic energy. The turbulent kinetic energy in the combustion chamber with optimized piston is nearly 30% higher than that of the original piston. Additionally, the optimized piston has a more uniform mixture and less dilute mixture near the spark plug. These all speed up the initial flame development. The optimized piston has a better fuel economy compared to the original piston. The research has certain engineering guiding significance for the development of methanol engine.
Keywords:methanol engine; piston optimization; turbulent kinetic energy; tumble; swirl; fuel economy