18-06-2012, 01:59 PM
design of an internal combustion
ABSTRACT:
Several new technologies have result all these technologies accomplish these goals by increasing the efficiency of an engine.
As whole ,these technologies are called variable valve actuation. achieve These technologies achieve a higher efficiency by reducing the constants of the engine. present project focuses on how to create an engine model and how engine simulation can be used to optimize such an engine. In addition the benefits of a particular variable valve actuation technology, cam phasing, will be explored.
INTRODUCTION:
The design of an internal combustion (IC) engine is a complex compromise between performance, fuel economy and emissions. These three factors are interrelated and they cannot be simultaneously optimized.
FIRST METHOD:
Thermodynamics shows that the higher an engine’s compression ratio, the higher its efficiency. However, the in-cylinder pressures and temperatures which result from higher compression ratios place an upper bound on an engine’s compression ratio. When an engine starts knocking, the progressive normal combustion is replaced by very fast detonation waves in the combustion chamber, and the engine can be severely damaged.
SECOND METHOD:
Another method of increasing the efficiency of an engine is reducing the mechanical losses associated with throttling. When an engine is throttling, a plate obstructs the air intake flow and causes a
pressure drop across the plate. Throttling reduces the amount of air induced into
the
engine, but it introduces flow losses which reduce an engine’s efficiency.
Furthermore once the physical parameters
such as displacement, cam profile and compression ratio are determined, a conventional
engine has nearly fixed performance, fuel economy and emissions properties. By making
an engine more efficient, one or more of these factors could be increased without
significantly compromising the others