An infrared optical diagnostic system was designed and implemented within a High Speed Small Bore diesel engine. A FORTRAN computer program was written to incorporate the work of NASA on the infrared emissions characteristics of combustion products. This program provided information which in turn allowed small bandwidth filters to be chosen at specific wavelengths in order to allow combustion products and their temperatures and concentrations levels.
The HSSB diesel was modified to accommodate optical access through the removal of an exhaust valve. The field of view of the system included a wide swath of the squish region as well as a slice of the reentrant lip of the piston bowl. Data was taken from this engine at high operating loads common in the work life of an automotive engine. This data was then interrogated using a slightly modified version of the computer program. Temperature fields as well as normalized concentration fields of water vapor and soot were computed at crank angle cases of 15, 25, and 35 degrees ATDC.
The results of this experiment showed a combustion process that was localized in nature. The soot and temperature plots seemed to agree very well with each other while the water vapor fields did not present results consistent with current views of the combustion process. Recommendations were made on how the system could be improved upon while expanding its usefulness as a diagnostic tool.