A Study of the Genesis Mechanism of Unburned Hydrocarbons in a Constant Volume Bomb

The genesis mechanism of unbured hydrocarbons (HC) in a turbulent flow field has been studied by using constant volume cylindrical bombs. To investigate the influence of the turbulence intensity on combustion duration and HC, two different types of turbulence, one was the turbulence generated by swirling flow and the other was the isotropic turbulence, were selected. Results show that HC decreases with increasing the turbulence intensity and is independent of turbulence properties and even weaker turbulence which has little affect on combustion duration has a great deal of effect on HC.

A special technique was devised to freeze a reaction at an arbitrary moment of combustion process. The following points have been made clear. First, the oxidation of HC continues for a while after the pressure has peaked. Second, the reaction rate of post flame oxidation increases with tubulence intensity, but the fraction of HC oxidized after the pressure has peaked is about 60% and is not influenced by the turbulence intensity.