Simulation of the Transient Performance of a Turbocharged Diesel Engine Featuring a Two Point Air Injection Transient Assist System

Growing global concern pertaining to climate change has meant that engine development has become more focused on engine emissions. A method of reducing the emissions of an internal combustion (IC) engine is to use smaller engines but recover power lost due to reduction in size by using a turbocharger or supercharger. Turbocharged vehicles are commonly used but they exhibit a weak point of poor performance under transient running conditions. The phenomenon, known as “Turbo-lag”, is most noticeable when a sudden load change is applied at lower engine speeds combined with rapid acceleration.

The work presented analyses a novel method of improving the transient performance of turbocharged engines by injecting air into both the compressor of the turbocharger as well as inlet manifold of the engine-known as a two point air injection system. The effect of two point air injection on the transient performance of a turbocharged engine as well as on emissions has been examined in the present work.

To analyse the effectiveness of the two point injection system a numerical investigation was carried out on Ricardo WAVE software. The simulation compares engine performance, compressor performance and emission output of the engine. The model has shown that the two point injection system substantially improves both engine performance and reduces the emissions out put from the engine.