A multi-process coupling study of scavenging pressure effect on gas exchange of a linear engine

Abstract

The linear engine is expected to operate with new gas exchange characteristics due to its unconstrained and adaptive dynamics. This study develops a simulation method that mutually transfers the coupling parameters between the piston motion model, generating model, combustion model, and scavenging model, and it iterates the calculation results of motion, combustion and scavenging for gas exchange predication. Then, the coupling effect of scavenging pressure fluctuation on gas exchange in a two-stroke linear engine is also investigated. The results indicate that unlike conventional engine systems, the linear engine reciprocation and compression ratio both increase first and then decrease with the enhancing scavenging pressure, namely the duration of gas exchange is shortened or prolonged, while the linear engine also provides high in-cylinder gas pressure for gas exchange, but the in-cylinder gas temperature reverses. The intake quality and escape amount of the cylinder both vary in positive correlation with the scavenging pressure, which leads to low trapping efficiency, although it cleans more exhaust. The results also find that high scavenging efficiency and fresh charge trapping efficiency can be obtained synchronously at an appropriately low scavenging pressure environment due to its adaptive motion.