Sea-Level Characterization of Electrically Assisted Turbocharger for Use on Aviation Diesel Engine 2024-01-1914

Airborne compression-ignition engine operations differ significantly from those in ground vehicles, both in mission requirements and in operating conditions. Unique challenges exist in the aviation space, and electrification technologies originally developed for ground applications may be leveraged to address these considerations. One such technology, electrically assisted turbochargers (EATs), have the potential to address the following: increase the maximum system power output, directly control intake manifold air pressure, and reignite the engine at altitude conditions in the event of an engine flame-out. Sea-level experiments were carried out on a two-liter, four-cylinder compression-ignition engine with a commercial-off-the-shelf EAT that replaced the original turbocharger. The objective of these experiments was to demonstrate the technology, assess the performance, and evaluate control methods at sea level prior to altitude experimentation. This work covers the baseline characterization of the EAT as a turbocharger, on-engine EAT electrical operation for boost control, and a demonstration of system power extension capabilities. The baseline characterization quantified the aerodynamic performance of the EAT through the engine power curve. Then, the motor-generator on the EAT was used to directly control the intake manifold pressure. During this operation, the EAT recovered 2.4% of the exhaust energy as electrical power at the maximum nominal engine power condition. During the power extension demonstration, the manifold pressure and fueling was increased simultaneously to maintain a constant equivalence ratio. This resulted in a 6% increase engine mechanical power output and an increase in total system power output (electrical power plus mechanical power) of approximately 9%. Examples for potential on-aircraft configurations and recommendations for altitude experimentation are also expressed.