Increases in fuel prices are constraining car manufacturers to produce highly efficient engines, noting greater regulation in terms of pollutant emissions. The greater complexity of modern engines has rendered the prototyping phase long and expensive. This is where engine modeling has in recent years become extremely useful and an indispensable tool when developing new engine concepts. This study deals with the numerical simulation and performance prediction for a turbocharged diesel engine with direct injection. To predict engine performance we developed a computer program for simulating the operation of a turbocharged diesel engine, and used the commercial software GT-Power to validate the simulation results. We then carried out a comparative study of indicated mean effective pressure, mean effective pressure, power, torque and brake specific fuel consumption obtained by an analytical model for thermodynamic cycle simulation of a turbocharged diesel engine using a computer program developed in Fortran and GT-Power. The Fortran program that was developed is currently used for modeling and the simulation of engine performance.
For different operating conditions of an internal combustion engine, the piston–ring–liner compartment represents one of the largest sources of friction and power losses. The aim of this article is to evaluate the effect of the compression ring profile on the main tribological performance of the lubricant in a four-stroke diesel engine. A one-dimensional analysis was developed for the hydrodynamic lubrication between the compression piston ring and the cylinder wall. A numerical method was applied to analyze the influence of different ring geometrical designs during the working cycle on oil film thickness, frictional force, and power losses. Our predicted results were validated with the Takiguchi data of a previous study, and they have shown a good agreement. The results in the current analysis demonstrated that the ring geometry profile, the engine speed, and load have a remarkable effect on oil film thickness, friction force, and friction power losses between the top ring and cylinder liner. Therefore, it would help in reducing friction as well as making a contribution to the improvement of engine performance such as torque, efficiency, and fuel consumption.
In this study, the thermodynamic performance of a turbocharged compression ignition engine with heat transfer and friction term losses was analyzed. The purpose of this work was to provide a flexible thermodynamic model based on the filling-and-emptying approach for the performance prediction of a four-stroke turbocharged compression ignition engine. To validate the model, comparisons were made between results from a computer program developed using FORTRAN language and the commercial GT-Power software operating under different conditions. The comparisons showed that there was a good concurrence between the developed program and the commercial GT-Power software. We also studied the influence of several engine parameters on brake power and effective efficiency. The range of variation of the rotational speed of the diesel engine chosen extended from 800 to 2100 rpm. By analyzing these parameters with regard to two optimal points in the engine, one relative to maximum power and another to maximum efficiency, it was found that if the injection timing is advanced, so the maximum levels of pressure and temperature in the cylinder are high.
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