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The sole purpose of combustion in a piston engine is to generate pressure in order to push the piston and produce work. Pressure diagnostics provides means to deduce data on the execution of the exothermic process of combustion in an engine cylinder from a measured pressure profile. Its task is that of an inverse problem: evaluation of the mechanism of a system from its measured output. The dynamic properties of the closed system in a piston engine are expressed in terms of a dynamic stage - the transition between the processes of compression and expansion. All the phenomena taking place in its course were analyzed in the predecessor of this paper, SAE 2002-01-0998. Here, on one hand, its concept is restricted to the purely dynamic effects, while on the other, the transformation of system components, taking place in the course of the exothermic chemical reaction to raise pressure, are taken into account by the exothermic stage.

Internal flow characteristics of a close coupled catalytic converter were examined by LDV measurements and high speed flow visualization. Although previous studies have been done on catalytic converters, they were conducted at steady state and using water flow seeded with a small quantity of tracer particles. The purpose of this study was to develop a better understanding of dynamic flows inside catalytic converters. The high speed flow visualization films and LDV results showed that areas of separation and circulation were present in the inlet region of the converter. Backflows into the neck of the converter were also observed. Each cylinder exhausted into a different region of the converter, with the front-middle region having the heaviest amount of flow. Large bursts of flow were created by each cylinder, while other regions of the inlet region showed backflows or very low flow rates. The midsection of the converter had a more uniform overall flow pattern.