دانلود کتاب اصول موتورهای احتراق داخلی

The subject of internal combustion engines is a practical agglomeration of many of the fields of engineering such as thermodynamics and combustion, fluid mechanics and heat transfer, mechanics, stress analysis, material science and electronics. Extensive research on the engines from all these allied fields, over the decades, continued to pour in to generate a strong database on which the design of modern engines has evolved. Among the important prime movers, the development work on internal combustion engines, both rotary and reciprocating types, has witnessed major changes primarily due to the fact that the development focus has shifted from achieving near complete combustion to one that can meet stringent pollution norms. This shift in focus, for example, led to the near-complete eclipse of the carburettor in SI engines yielding space for the advent of high performance fuel injectors. Lean combustion began to be studied in detail because of its economical as well as environment-friendly aspects. However, for achieving the benefits associated with lean combustion technology, the equivalence ratio needed to be brought down to below 0.7. This is often associated with combustion instability problems. Consequently, new concepts like stratified charge engines etc. are being thoroughly investigated. It is expected that some of them will be in place shortly for automotive engines. On the downstream side of the exhaust, product gases are no more allowed to be simply discharged out of the engine, as was the case earlier. It has to be treated before it can be discharged into the atmosphere. Thermal reactors were the forerunners in this regard. Soon those were promptly replaced by catalytic converters. The use of the more conventional threeway catalytic converters dictates that for its efficient operation, the engine must be operated under stoichiometric combustion condition. This opened up the way for the advent of electronic feedback control in the field of internal combustion engines. Ignition system, typical of conventional SI engines, has also undergone major changes and components like mechanical breaker points have been left out from the point of view of operation at high speeds. These led to the extensive use of tailor-made transducers and complex control systems in a modern SI engine. The conventional CI engine satisfactorily used the conventional ‘Individual pump and nozzle system’ for over a few decades. While the use of such conventional type of injectors are still in place for large size diesel engines, small and medium size engines are nowadays built with ‘Common Rail Technology’. Again the extensive use of electronic hardware and controls paved the way for more compact, high efficiency engines. The thermodynamic basis of the analysis has not changed over the years and is not expected to change either but the combustion aspect has now been extended. The fluid mechanics of flow through the engine which includes the intake and exhaust processes and charge motion within the cylinders and the role of turbulence are being assessed afresh. While the above description highlights only some of the important trends in the field of engine research, some other development areas like research on the material development, structural aspects, noise and acoustics etc. do not usually find a place in the more common texts of internal combustion engine. This textbook, written mainly for the undergraduate students of engineering, presents a modern approach to the study of internal combustion engines. The working professionals in different automobile or related industries will also find this book useful. The contents include the fundamentals of the most common types of internal combustion engine with a major emphasis on the reciprocating variety. A first level discussion on the elementary aspects of gas turbine has also been included. The purpose of this book is to apply the principles of basic thermodynamics and fluid mechanics to the analysis of internal combustion engines. We have also included a dedicated chapter on electronic control and devices so that students get an exposure to an elementary knowledge about the functioning of control systems in engines. Numerical problems have been incorporated wherever possible. Needless to say, that a number of source materials have been used during preparation of the text material and the associated numerical problems. Not all of them find place in the list of references due to the paucity of space but the authors gratefully acknowledge them.