Development of a Computer Model to Simulate the Injection Process of a Diesel Engine

Abstract

The diesel engine injection system is greatly responsible for the emission of pollutants to the atmosphere, noise generation, and engine performance. Proper synchronization of the exact amount of fuel that can be burnt according to each crankshaft position is essential to achieve maximum power, consumption economy, and combustion without residues. In this sense, when designing an injection system, all of these factors must be taken into account. During the optimization, however, the improvement of some of them may result in detriment to others. For this reason, to achieve the system optimization, the relationship between the aforementioned variables and the parameters that characterize the injection must be established. According to this, it is important to design a strategy that allows the named “reverse modeling of the injection system”, that is to say, to determine the injection system dimensions according to the system requirements. In the present work, an iterative computer model based on the continuity and energy equations, solved by finite differences algorithms, has been proposed. This model has been designed for a Bosch rotary pump and makes it possible to plot the performance of the pressure lines in the different combustion chambers, the valve lift curves, and the fuel flow injected per cylinder and cycle. In this sense, we can conclude that the proposed computer model predicts accurately the opening and closing processes in the injector needle, as well as the pressure curves in the last division of the high-pressure tube.