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An experimental and theoretical investigation has been performed on the flow and pressure loss in axisymmetric catalytic converters and isolated monoliths under steady, isothermal flow conditions. Monolith resistance has been measured with a uniform, low turbulence, incident flow field. It has been found that the pressure loss expression for fully developed laminar flow is a good approximation to observations for x+ greater than 0.2. However, for x+ less than 0.2 the additional pressure loss due to developing flow is no longer negligible and a better approach is to use the correlation proposed by Shah (16). From experimental studies on the axisymmetric catalytic converters non-dimensional power law relationships have been derived relating maldistribution and pressure drop to expansion length, Re, and monolith length. These expressions are shown to generally fit the data well within ±5%.

The purpose of this paper is to characterise barrel swirl behaviour in a production four-valve engine with pentroof chamber. Steady flow analysis showed that the insertion of tubes into the cylinder head's induction tracts increased the tumbling ratio of the in-cylinder flow field at intake valve closure. A comparison of LDA measurements, conducted along the spark plug axis, for tubes and no tubes inserted yielded the following conclusions. The results indicated that the barrel swirl generated was not efficiently breaking down into turbulence but forming two counter-rotating vortices in the horizontal cylinder plane. The turbulence levels and cycle-to-cycle flow variations towards the end of the compression stroke increased with tumbling ratio. The former suggested faster combustion rates if applied to a lean burn engine, however, the latter suggested greater cyclic combustion instability and may limit lean burn capability.

The purpose of this paper is to characterise the flow field through the inlet valves, and tumble to swirl conversion tube of a steady state flow rig using HWA. LDA and CFD techniques. Three cylinder head configurations were developed which were found to produce three levels of barrel swirl motion. The swirl precesses around the central core of the conversion tube at all degrees of swirl. Varying degrees of swirl produced differing axial velocity profiles, and flow reversal occurred in the central core of the conversion tube for the high swirling case. The results obtained for this study indicate that care must be exercised when deducing the barrel swirl ratio for real engines from steady flow rig analysis.

This paper describes an investigation into the combustion of simulated biogas in a spark ignition engine. The biogas has been simulated by the mixing of methane with carbon dioxide to create a range of biogas compositions. The ratio of methane to air has been maintained at a constant throughout the study. The quantity of carbon dioxide was increased until the engine stalled at a concentration of 35%. The engine employed in the investigation was a 1.3 litre Rover ‘A’ series unit which had four cylinders, overhead valves, a compression ratio of 9.5:1 and was run at a fixed speed of 1500 rev/min. The in-cylinder pressure signals was recorded using a high speed data acquisition system and was then used as an input into a two zone combustion model to calculate the mass fraction burnt. The model was adapted to the combustion chamber geometry of the engine under study which enabled the turbulent burning velocity values to be obtained.