The effect of combustion chamber geometry layout on combustion and emission

In this paper some results concerning the combined effect of the fumble flow and combustion chamber geometry layout variations on flame front shape and its propagation through homogenous mixture of isooctane and air are presented Spatial distributions of NO in different combustion chamber geometries are presented as well. The basic combustion chamber geometry layout considered consists of the flat head with two vertical valves and a cylindrical bowl subjected to variations of depth and squish area. All results presented were obtained by dint of multidimensional modeling of reactive flows in arbitrary geometry with moving objects and boundaries with modified KIVA3 and KIVA3 V source codes. Two additional computer codes were applied to generate boundary conditions for KIVA3 V calculations with moving valves. The AVL TYCON code was used for the calculation of valve lift profiles, and A VL BOOST code was used for the calculation of relevant data set in the valve regions. Different combustion chamber geometry layouts generate different levels of squish, and the combustion effects in essence depend on the interaction of that flow with tumble. It was found that for particular combustion chamber shapes with different diameter/depth aspect ratios entirely different flame front shapes and propagation velocities were encountered primarily due to variations of fluid flow patterns in the vicinity of top dead center

A quick, simplified approach to the evaluation of combustion rate from an internal combustion engine indicator diagram

In this paper a simplified procedure of an internal combustion engine in-cylinder pressure record analysis has been presented The method is very easy for programming and provides quick evaluation of the gas temperature and the rate of combustion. It is based on the consideration proposed by Hohenberg and Killman, but enhances the approach by involving the rate of heat transferred to the walls that was omitted in the original approach. It enables the evaluation of the complete rate Of heat released by combustion (often designated as gross heat release rate or fuel chemical energy release rate), not only the rate of heat transferred to the gas (which is often designated as net heat release rate). The accuracy of the method has been also analyzed and it is shown that the errors caused by the simplifications in the model are very small, particularly if the crank angle step is also small A several practical applications on recorded pressure diagrams taken from both spark ignition and compression ignition engine are presented as well