Summary on optical diagnostic technology of piston type internal combustion engine

In the research and development of piston type internal combustion engine, the design of optical engine and the application of optical diagnostic technology are important means for revealing working process of internal combustion engine. As the non-contact measurement method, the optical diagnostic technology may make measurement more accurate and profound under the precondition where the interference with test scene is reduced as much as possible; simultaneously, for measurement and analysis of resultants including spray pattern in cylinder, velocity field and soot, etc, it may provide reliable experimental basis for three-dimensional computational fluid dynamics. This paper has firstly introduced the design classification of optical engine for optical diagnostic technology, including early design of optical channel, the optical engine with bottom fenestration of the existing engines and three-direction optical engine, etc. Then, according to different stages of working process of engine, it has discussed application of all kinds of optical diagnostic technologies; finally, it summarizes the development trend of optical diagnostic technology, and indicates combined application of several kinds of diagnostic technologies and that the transformation from one-dimensional measurement to multi-dimensional measurement is the development trend of optical diagnostic technology of piston type internal combustion engine.