1-D simulation of turbocharged SI engines focusing on a new gas exchange system and knock prediction

Abstract: This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented