Fuel Injection Technique to Control the Flame Limits of a Twin-Plate Flameholder

This paper describes the experimental results of the characteristics of a twin-plate flameholder with by-path fuel (BPF) injection technique. Reacting flow visualization with the addition of TiCl4vapor in the mixture demonstrated that the enhanced vortex motions by the slit jet formed an S-shaped flow structure within the recirculation zone behind the twin-plate flameholder. Measurements of fuel distribution indicate that the propane fuel concentrations at the slit exit (x/B = 0. 1) increase from 9.16% to 12.10%, i.e., local fuel concentration increases about 32%, when the BPF increases from 0 to 5.0%. This phenomenon is attributed to the small slit stream through the open slit between the two plates of this flameholder. Test results also show that the ignition limit extends from (φo= 0.130 to φo= 0.104 as the BPF increases from 0 to 5.0%, i.e., extending 20% in the flame ignition limit. This means that a small BPF injection can effectively enhance the ignition capability of the twin-plate flameholder. A similar effect happens to the blowout limit. The lean blow out limit extends from φo= 0.144 to φo= 0.103 as the BPF increases from 0 to 5.0%, i. e., increase by 28.5% in lean blow out limits due to a small amount of BPF. It can be concluded that the BPF injection technique can be taken as the control mechanism to enhance the flame stability limits of the twin-plate flameholder.