Test stand design for a high-compression, direct-injection spark-ignition methanol-fueled engine and results of various engine configurations.

摘要

A research engine test stand was designed and built for engines which exhibit some of the desired traits of both the automotive gasoline engine and modern diesel engine. This spark ignition engine is fueled by M100 (99.99% pure methanol), operates under high compression (19.3:1) and utilizes direct fuel injection. The engine head was designed to accept a removable combustion chamber, which allows testing to determine the effects of combustion chamber design on engine performance. This paper provides an explanation of the hardware included in the experimental setup of the engine components including the fuel, cooling, intake and exhaust systems, along with installation of instrumentation and controls for the engine. Performance results were gathered from four combustion chamber/injector configurations, and results are presented.; High speed flow visualization of different injector nozzles indicated that the most ideal injector fuel spray resulted with a wide spray angle direct injector (45°) and a needle lift of 50mum. Four engine configurations were tested examining two direct injector needle lifts, and three combustion chamber bowl volumes while compression ratio was held at 19.3:1. The 50mum injector configuration produced more consistent engine operation (as measured by COV in IMEP) than did the 65mum needle lift injector, especially at part load. Three combustion chamber designs were considered: one with a hemispherical bowl volume containing 17.5% of the total compressed volume, a second with a hemispherical bowl volume containing 32% of the total compressed volume, and a third with a hemispherical bowl in the piston, and a non-hemispherical bowl in the head, with a bowl volume containing 35.7% of the total compressed volume. The smaller bowl volumes produced higher IMEP and smaller COV in IMEP than the larger chamber bowls under globally lean conditions (lambda = 2.0--2.75). The larger bowl volumes showed higher IMEP and smaller COV in IMEP than did the smaller chamber bowls under (relative) globally rich conditions (lambda = 1.5, 1.75).