VISUALIZATION AND MEASUREMENTS OF TURBULENT FLAME PROPAGATION IN A CONSTANT VOLUME CHAMBER

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In the spark-ignition engines, mixtures introduced in the combustion chamber are ignited and a flame propagates to convert the mixtures to a burned gas. For improving the thermal efficiency of the engines, time consumed by this process should be reduced. This research aims at the understanding of the mechanism of turbulent flame propagation in a constant volume chamber. The research consists of two types of experiments, one is for the flame propagation in a swirling flow and the other is for that in a nearly homogeneous isotropic turbulence. In the former experiment, a premixed gas is introduced in the chamber tangentially along its side wall. The strength of this swirling flow decays with time. The mixture is ignited at an appropriate time after the mixture starts to be introduced. When this time is short, so that the strength of the swirl is strong, a burning time is very short while the time is long, the burning time becomes long. It is concluded that the burning time is well correlated to the swirling velocity of the unburned gas flow. On the other hand, in the second experiment, the mixture is introduced radially from eight ports on the side wall. So, thereis no main flow such as a swirl. Turbulence intensity of the mixture was measured by a hot wire anemonater and it decays with a time after the mixture is introduced. Varyng the time of ignition, the burning time was measured for different turbulent intensities. It is elucidated that the burning time is a particuler function of the turbulence inetnsity.