| The performance characteristics of a novel uniflow-scavenged gasoline direct-injection two-stroke engine are presented in this thesis. The feature that makes this engine novel is the engine head. It contains multiple passive check valves used to control airflow into the cylinder. A thin platelet is contained within the check valve cavity that reacts to the pressure difference across the engine head. When the intake plenum pressure is higher than the cylinder pressure, air flows through the check valve. When the intake plenum pressure is lower than the cylinder pressure, airflow is not permitted through the check valve. This engine head design provides asymmetrical intake valve timing and abolishes the need for traditional cams and the associated valve train. In combination with an external Roots-type supercharger and exhaust ports at the base of the cylinder wall, the novel head provides top-down uniflow air scavenging. The engine is equipped with gasoline direct injection to eliminate fuel short-circuiting, a common problem with traditional two-stroke engines.;Motoring tests were performed to identify check valve characteristics and revealed that the platelets have a finite closing time that is dependent on engine speed. The engine was connected to a hydraulic dynamometer for fired engine tests. The head design was validated at low engine speeds ranging from 1250 to 2000 rpm. Both indicated torque and indicated specific fuel consumption performance diminished with increasing engine speed, revealing that improvements in engine scavenging and mixture preparation are necessary. |
