One-Dimensional Fluid-Dynamic Model for Catalytic Converters in Automotive Engines

The aim of this paper is to present a new and simple approach to the one-dimensional modelling of the global fluidynamic behaviour of the catalytic converter placed in the automotive spark ignition engine exhaust system. Being that this component is the first singular element encountered by the flow, it imposes an influential boundary condition in the interaction with the cylinder exhaust process, thus affecting greatly the engine performance.

A specific submodel has been developed, able to represent the main phenomena taking place in the exhaust flow: mean pressure drop, mean temperature variations and instantaneous pressure wave reflection and transmission. This submodel has been linked to a one-dimensional wave action model, which is, this way, able to predict the precise interaction and mutual influences between engine and catalytic converter. The results of the model have been experimentally validated with tests on engine in real running conditions.