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

在火花点火发动机中，引入燃烧室的混合物被点燃，火焰传播，将混合物转化为燃烧的气体。为了提高发动机的热效率，应该减少这一过程所消耗的时间。本研究旨在了解定容燃烧室内湍流火焰传播的机理。研究包括两类实验，一类是关于旋流中火焰传播的实验，另一类是关于近均匀各向同性湍流中火焰传播的实验。在前者的实验中，预混气体沿燃烧室侧壁的切向引入。这种漩涡的强度会随着时间的推移而减弱。在开始引入混合物后，在适当的时间点燃混合物。当这个时间短时，使旋涡的强度很强，燃烧时间很短，而时间长，燃烧时间变长。结果表明，燃烧时间与未燃气流的旋转速度有很好的相关性。另一方面，在第二个实验中，混合物是从侧壁的八个端口径向引入的。因此，没有像漩涡这样的主流。用热线风向仪测量了混合气的湍流度，在混合气引入后，湍流度随时间衰减。通过改变点火时间，测量了不同湍流强度下的燃烧时间。阐明了燃烧时间是湍流强度的特殊函数。

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.