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Time resolved digital particle image velocimetry (TRDPIV) data is presented for the in-cylinder flow field of a motored four stroke multi-valve direct injection spark ignition (DISI) optical internal combustion (IC) engine. It is widely accepted that IC engine performance, in terms of both engine emissions and efficiency, is fundamentally affected by the in-cylinder air motion. Therefore improved knowledge of the fundamental fluid flow processes present during the intake and compression phase of the engine cycle is required. More specifically, increased understanding of the flow field cyclic variation will facilitate accurate control of the mixing and ignition development. This paper highlights the application of a new TRDPIV system to provide both spatial and temporal in-cylinder flow field development over multiple engine cycles for improved understanding of cyclic variation.

Particulate number (PN) standards in the current ‘Euro 6’ European emissions standards pose a challenge for engine designers and calibrators during the warm-up phases of cold direct injection spark ignition (DISI) engines. To achieve catalyst light-off in the shortest time, engine strategies are often employed which inherently use more fuel to attain higher exhaust temperatures. This can lead to the generation of locally fuel-rich regions within the combustion chamber and the emission of particulates. This investigation analyses the combustion structures during the transient start-up phase of an optical DISI engine. High-speed, colour 9 kHz imaging was used to investigate five important operating points of an engine start-up strategy whilst simultaneously recording in-cylinder pressure.

Time resolved intake runner flow field data is presented for a motored single cylinder four stroke, direct injection spark ignition (DISI) optical internal combustion (IC) engine with an optically accessible intake runner. Previous studies have shown the fundamental influence in-cylinder air motion has on engine performance, exhibiting a controlling factor on the mixing process and early flame kernel development. An improved understanding of the in-cylinder flow fields during the intake and compression process leading up to ignition is required. However, knowledge of the intake runner flow field during the intake phase of the engine cycle is required to establish the effect of intake runner flow variation on in-cylinder flow field development. This paper presents the use of a new time resolved digital particle image velocimetry system within the intake runner to study runner flows and their variation over many engine cycles.