Abstract
An experiment was accomplished using a constant volume combustor to ensure fundamental data in advance of the development of a new sub-chamber attached lean burn engine. The volume of sub-chamber is set up to occupy less than 1% of whole combustion chamber, the equivalence ratio of pre-mixture in the main chamber and sub-chamber is uniform, and numerous narrow passage holes are arranged to induce simultaneous multi-point ignition in the main chamber by flame jets including radicals from the sub-chamber.
When the tiny sub-chamber was attached to the main chamber, the overall burning time including the ignition delay time became very short compared with that of the single chamber. And maximum pressure slightly increased with the diameter of passage holes because the long contact time of early flames increases the cooling loss into the wall of the main chamber in contrast to the single chamber.
Lean limit is extended as about ER=0.15î0.2 because the shortening of flame propagation distance decreases the possibility of miss fire in the sub-chamber and the concentrated supply of induced radicals increases the propagation intensity of the early flames in the main chamber. And also, it is known that the combustion of the sub-chamber attached type proceeds very rapidly.