Preliminary designs for the cylinder heads of Scania’s next generation Diesel Engine have been investigated by the means of PIV measurements on a steady test rig. General structures present in the flow have been investigated, with a specific focus on Swirl motion due to its well documented impact on combustion efficiency and pollution generation. The first set of measurements was acquired in the tumble plane. A method to perform efficiently PIV measurements was introduced, which consists in rotating the experimental setup rather than the PIV measurement instruments. As a consequence, a considerable amount of work is saved and a great number of measurement planes can be acquired. This method has allowed to reconstruct a 3D3C picture of the flow in the cylinder. Such 3D3C direct measurement of flow in a test rig cylinder had not been reported previously in the literature, as far as the author is aware of it. The second set of measurements was acquired in the swirl plane. General patterns in the swirl velocity fields have been identified. The author introduces the hypothesis that shifting down the measurement position may, to some extend, be equivalent to observing the flow evolve in time in the real engine situation. Measurement performed far enough under the valves exhibit clear and stable swirling vortex structure with the cylinder heads investigated. This may explain for the validity of the combustion models used in the industry that, despite apparent over simplification of the flow situation, have proved in good agreement with engine tests.

This degree project is focused on the study of the tumble and the swirlmotions, which develop during the intake stroke, inside a cylinder of a Dieselengine.Nowadays, the reduction of fuel consumption and emissions is a primaryaspect for automotive companies, including Scania. Then, an efficient combustionprocess is required, and a fundamental role is played by tumble andswirl motion.These motions have been studied by means of the Particle Image Velocimetry(PIV) technique. In particular, two different cylinder head designshave been investigated, focusing on the structures present in the flow andtheir evolutions inside the cylinder. Finally, these results have been comparedwith LES results, in order to validate the latest. Analysing the swirl motion, it has been possible to identify three mainregions, along the cylinder, characterized by different vortex structures. Inaddition, the velocity field into the entire cylinder volume has been extractedby means of a three-dimensional three-component reconstruction.