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A comparison between conventional and bio-derived fuel spray characteristics is described in this paper. Radial distributions of drop size, axial and radial velocity components were measured using a Phase-Doppler Anemometer (PDA). A digital visualization system including a CCD camera was used to estimate the spray tip penetration. Fuel was injected through a single hole diesel injector into a test section at ambient pressure. An empirical expression was found to estimate the spray tip penetration at ambient conditions.

In this paper, a parameter to quantify the cyclic variability in first stages of combustion is presented, as an evolution of the parameter proposed by Hill and Kapil. This parameter relates the mean time necessary for the initial flame to reach the periphery of a turbulence eddy structure moving from the flame kernel position. This parameter is used in combination with quasi-dimensional models in order to predict and analyze small-scale turbulence contribution to cyclic variations. The cyclic dispersion parameter could be introduced in the predictive models as a delay in the combustion beginning. The parameter is compared with the experimental standard deviations in mass burned fraction at spark time obtained from others researchers works and own experimental data. A satisfying agreement between predictions and measurements is achieved.

An experimental procedure to determine the two components of the crankshaft force on the bearing cap is presented in this work. The method is based on the use of two load cells, one in each bearing cap bolt. A system to calibrate the force transference from the bearing cap to the load cells has been used. This system allows the calculation of the two components of the crankshaft forces as a function of the load cells signals. Some experiments have been done with this system, and the results of a firing and motored engine have been compared in order to know the influence of combustion and inertia forces on the crankshaft load in the bearing cap. The results are compared with a model for the dynamics of the piston-connecting rod-crankshaft system.

In this paper, models developed to determine exhaust emissions from Spark Ignition engines are shown. Concretely, a model based on chemical kinetics for determining CO and NOX emissions is presented. Also it is shown a model for the determination of the HC exhaust emissions based on retention in crevices, wall quenching, and in-cylinder and exhaust pipe post-flame combustion processes. Both models are included in a quasi-dimensional multizone model that permits the fast analysis and prediction of combustion in homogeneous-charge SI engines. Finally, results obtained from the models are compared with experimental exhaust emissions measured in a test bench.