Genom statistisk analys utvärdera geometriska parametrars påverkan på ett XPI- cylinderhuvuds snurrtal
This Master Thesis is a product development project that has been carried out in cooperation with Scania CV AB. The purpose has been to find the relationship between geometric parameters and the swirl number for an XPI- cylinder head in order to improve the design specification.The increased focus on environmental issues from society leads to tighter emission legislations for the truck manufactures. In order to drive the development forward considerable resources are spent on research and development on diesel engines and its combustion process. The inlet air has a significant impact on the formation of emissions and the flow that is desired is called swirl. Swirl is achieved by making the air rotate around the vertical axis of the cylinder.Earlier cylinder heads that has been developed at Scania CV AB have shown clear relationships between geometric parameters of the cylinder head and the swirl number. With the new XPI- cylinder head observations have been made that other parameters also affect the swirl.By experience many parameters that affect the swirl and the airflow down the cylinder are known. Based on this knowledge and interviews with experts at Scania CV AB the parameters for the study have been developed and specified.After defining the geometric parameters, 33 in total, 120 cylinder heads were measured and swirl tested.The statistical investigation was carried out by Ekaterina Fetisova as a part of her bachelor degree project for the Department of Mathematical Statistics at the University of Stockholm. The investigation used multiple linear regression to develop six models that describes the relationships between the geometric parameters and the swirl number.The developed models provides an explanation rate between 54-60 % between the variance of the geometrical parameters and the variance of the swirl. A few parameters stand out as more important than others, some parameters more expected than others.Conclusions that are drawn are that the investigation probably is missing important parameters and that there is a great complexity between the geometric parameters and the swirl number. To get a better understanding of the impact that each channel has on the swirl number recommendations are made to swirl test one channel at a time and to find the relationship between the geometric parameters for each channel and the swirl number.