Jean Rabault, PhD candidate, Mathematics Department, UiO
PIV investigation of the flow structures developing in a parallel valves Diesel engine cylinder during the intake stroke.
Jean will present us some aspects of his Master Thesis work, that was done as a collaboration between Scania CV AB (Södertälje) and KTH (Stockholm).
Diesel engines are largely used for powering vehicles. Legal requirements are regularly introduced that diminish the authorized level of pollutants emitted by such engines. Several methods can be applied to reduce pollutants emissions. One of them consists in optimizing the combustion process in the engine, by controlling the flow structures generated during air admission. The admission flow generated by a parallel valves Diesel engine cylinder head was investigated by stereoscopic Particle Image Velocimetry in a steady flow test bench through measurements in the swirl and tumble planes. By combining several sets of measurements a full three-dimensional, three-component reconstruction of the mean flow was made. The flow out of the valves was found to form a jet which collides with the opposite wall before flowing down along the walls into the cylinder, leading to the formation of a recirculation bubble in the tumble plane. In the swirl plane a complex vortex pair structure is found near the valves from which the strongest vortex becomes predominant and a single coherent swirling structure can be observed lower down in the cylinder. Vortex centre tracking was used to analyse the stability in time and space of the single swirling structure.