Computational fluid dynamic analysis of unsteady compressible flow through a single cylinder internal combustion engine

The internal combustion engine has evolved over the past hundred years as the most important prime mover for various applications. Several related technologies have been developed to improve the performance and efficiency of operation of the engine. Improvements in computer technologies in the past 20 years have provided engine researchers with powerful tools to optimize engine design and to meet increasingly stringent emission requirements. Computational Fluid Dynamics, which is used in this thesis, is one such tool that enables study of complex systems in great details. The technique was used to study a new valve design patented by Caterpillar Inc. called the Monovalve.;A MATLAB based computer program using one-dimensional computational fluid dynamic modeling techniques has been developed to analyze the flow through the intake and exhaust pipes on a two-valve, single cylinder engine. The 1D simulation model enables quick study and optimization of various intake and exhaust system variables such as pipe length, valve timing, valve lift etc. The one-dimensional model was validated by comparing with results published in literature.;Two-dimensional computational analysis was performed on the two-valve engine using the popular CFD code FLUENT. Results of the two-dimensional analysis were compared with those of the one-dimensional model and both techniques were used to optimize the valve timing of the two-valve single cylinder engine.;The techniques were then used to study the Monovalve design concept and the performance of the system was compared with those of the two-valve system to asses its merits and demerits. The effect of various valve design parameters was also studied to optimize this new concept.;The results of this study showed that the Monovalve design improves the volumetric efficiency of the engine significantly because of the lower restriction offered by the valve. The study of variation of valve design parameters provided several insights in to the functioning of the complex system and could provide several guidelines for future Monovalve designs.