Experimental Study on Effect of Electrode Location on Ion Current

In an attempt to use ion current method on a suction flame holder for combustion diagnosis, the position of the detection electrode that has the significant effect on ion current, should be investigated. The objective of this study was to experimentally investigate the ion current distribution in different combustion zones by changing the electrode length and streamwise location. An ion current acquisition system was built on basis of the principle of Langmuir probe, and experiments were conducted under different fuel-air ratios ranging from 0.008~0.022. The results suggest that the ion current distribution obeys the same regulation at different fuel-air ratios. With the electrode length increasing, the ion current increases first, then decreases, and finally presents a unimodal curve. As the electrode streamwise location increases, the ion current demonstrates a linear decrease rule. The maximum ion current is obtained in the case that the electrode length and streamwise location equals 60mm and 0.75. Since the larger ion current provides the wider range for setting the misfire threshold, the position where the maximum ion current occurs can be a better choice for arranging the electrode.