Mathematical modeling of the two-stroke crankcase scavenged spark ignition engine working process

Abstract

Abstract A simulation for the analysis of the working process of two-stroke crankcase scavenged SI (spark ignition) engine is introduced. For this work, the entire work process is divided into the intake process in the carburetor, combustion process and the scavenging process. The consideration of fluid flow in the carburetor is divided into several zones according to the change in the cross-sectional area of the fluid flow. This is useful for rationally selecting the geometrical design parameters of the intake process leading to the crankcase through the air filter, carburetor, and inlet. The calculation model in the carburetor is solved numerically using a gas dynamics model. There are several methods for simulating thermodynamic processes occurring in the cylinder, but a zero-dimensional model is provided in this paper. The scavenging process in the analysis of the working process of two-stroke crankcase scavenged SI engine is a very complex thermodynamic process. In the scavenging model analysis, there are zero-dimensional scavenging model, two-zone scavenging model, and multi-zone scavenging model, but a multi-zone scavenging model is applied in this paper. In case of the multi-zone scavenging model, it is very important to determine the ratio of each zone for the accuracy of the simulation, and there is an example on it in this paper. In the two-stroke crankcase scavenged SI engine, the engine performance change according to the change of the transfer ports opening angle is explained with an example.