Tim Persoons

Automotive Exhaust Systems with Close-coupled Catalysts: Optimal Design Rules Based on Catalyst Flow Distribution and Manifold Gas Dynamics Tim Persoons

Increasingly stringent vehicle emissions legislation has lead to the integration of catalytic converters into the automotive exhaust manifold. A uniform catalyst flow distribution is crucial to minimize pollutant emission and pressure loss, and avoid catalyst degradation. This work establishes objective design criteria for these systems. The methodology enables high-resolution velocity measurements in the manifold, using a charged engine flow rig and oscillating hot wire anemometer. Experiments reveal local flow reversal and strong resonance fluctuations. Numerical models predict the flow dynamics beyond the scope of the experiments, and help to understand the gas dynamic resonances. The book explains how steady-state flow simulations can accurately predict transient flow in a fired engine. Design criteria are formulated for catalyst manifolds, predicting the collector efficiency in terms of flow uniformity from an early conceptual stage. The literature review, methodology and findings of this book are relevant for academic and industrial engineers interested specifically in automotive catalyst research and design, or experimental fluid dynamics in general.