Effect of turbine upstream geometry on pulsating flow and turbocharged si-engine performance.

Abstract

The pulsating exhaust flow propagates through the exhaust line upon opening of exhaust valves while carrying a high amount of energy (high pressure and temperature). The amount of energy delivered to the turbine could be affected by turbine upstream geometry along with the propagation. Therefore, in this study, the impact of the turbine upstream geometry (diameter, length of exhaust runner, and exhaust manifold volume) on pulsating flow and engine & turbocharger has been investigated using 1D engine simulation packages, AVL-BOOST. A validated 1-liter 3-cylinder SI-engine model was utilized as a base engine model. The simulation captured how different geometry influences the pulsating pressure profile and the impact on system-level performance and behavior. The current research highlighted that the exhaust manifold volume is strongly associated with exhaust resistance, scavenging, pulsation, knocking, and fuel economy. By minimizing unnecessary volume in the exhaust manifold, it presents high potentials to improve low-speed torque (∼15 %), fuel consumption (∼2.4 %), brake thermal efficiency (∼1.4 %), scavenging and knock resistance against the baseline model.