tailieunhanh - Internal Combustion Engines Fundamentals Episode 1 part 11

Tham khảo tài liệu 'internal combustion engines fundamentals episode 1 part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 372 INTERNAL COMBUSTION ENGINE FUNDAMENTALS view through the piston then propagates outward from the spark plug location. The blue light from the flame is emitted most strongly from the front. The irregu- I lar shape of the turbulent flame front is apparent. At TC the flame diameter is 1 about two-thirds of the cylinder bore. The flame reaches the cylinder wall farthest I from the spark plug about 15 ATC but combustion continues around parts of 1 the chamber periphery for another 10 . At about 10 ATC additional radiation I initially white turning to pinky-orange centered at the spark plug location is I evident. This afterglow comes from the gases behind the flame which burned 1 earlier in the combustion process as these are compressed to the highest tem- I peratures attained within the cylinder at about 15 ATC while the rest of the I charge 3 I Additional features of the combustion process are evident from the data in I Fig. 9-2 taken from several consecutive cycles of an operating spark-ignition engine. The cylinder pressure fraction of the charge mass which has burned determined from the pressure data see Sec. and fraction of the cylinder volume enflamed by the front determined from photographs like Fig. 9-1 are shown all as a function of crank Following spark discharge there is a period during which the energy release from the developing flame is too small for the pressure rise due to combustion to be discerned. As the flame continues to grow and propagate across the combustion chamber the pressure then steadily rises above the value it would have in the absence of combustion. The pressure reaches a maximum after TC but before the cylinder charge is fully burned and then decreases as the cylinder volume continues to increase during the remainder of the expansion stroke. The flame development and subsequent propagation obviously vary cycle-by-cycle since the shape of the pressure volume fraction enflamed and mass fraction burned curves for each