Abstract
Abstract
Due the qualities in the daily applications, internal combustion engine is today a highly used machine, its most frequent application being automotive traction. In the time, two variants was developed and researched, respectively the spark-ignition engine and compression-ignition engine. This two variants was developed and cover a large area lengthways time, in correlation with evolution of the researches and practical possibilities to obtain new solutions. In 1987 year, was estimated that, in the world, exist about 700 million vehicles in traffic, equipped with internal combustion engines, with a growing rate of 30 to 40 million each year. About 80% of this vehicles was equipped with spark-ignition engines. Today, compression-ignition engine (diesel engine) frequently imposed, have in mind advantages in the traction. The main advantages which imposed diesel engine are in correlation with low consumption and the possibility to resolve, easily, the big problem of the pollution with the low costs.
In these conditions, the necessity to improve construction and operation appeared, the main purpose being stating the most adequate computation methods for thermal and gas dynamics processes. Final purpose is numerical simulation of engine operation in order to find out optimum constructive versions already during design stage. Numerical simulation of engine operation can be achieved only basing on specific mathematical models able to take into account the multitude of factors influencing the complex phenomena taking place during the working cycle. The mathematical models are basing on physical models referring to the phenomena and consist in mathematical expression of these as well as in effective solving methods. Numerical modeling of a working cycle with a high level of accuracy referring to the real working cycle is one of the main goals of research and design activity. It must be mentioned that the among all stages of achievement of an internal combustion engine, design and modeling produce the smallest amount of costs. In case of errors, conduct to the next achievement stages until manufacturing of functional model, these increase by a step ratio of ten and so on, later passing to the prototype. This is the reason why modeling of internal combustion engines operation is so important to be of good quality, allowing these case decrease of research time and costs, research of design period, decrease of moral wear of the engines, increase of efficiency as well as increase of exploitation period combined with insult control. Already, when the first internal combustion engine appeared, the efforts of the specialists focussed on understanding the working principles and improving constructive solutions. Competition for to obtain engines with optimum operating performances (powerful, economical, reliable, silent, as non-polluting as possible) basis on continuos improving of mathematical modeling of real working cycle as well as on improving experimental investigation methods for the phenomena taking place in the engine.