A preliminary investigation on combustion instability in a vapor flameholder combustor

Experiments were conducted on combustion instability in a modal combustor with vapor flame holder. Three equivalence ratios were chosen, 0.4545, 0.5454, 0.6363, respectively. The pilot fuel percentage increases from 2% to 36% with interval 2%. The dynamic pressure transducers were used to measure combustor dynamic pressure frequency and magnitude at different equivalence ratios and different pilot fuel percentages. In order to compare with vapor flameholder, experiments were also conducted with V-gutter flameholder at three overall equivalence ratios. The results show that 130Hz and 203Hz instability modes are excited in vapor flameholder combustor. Only 203Hz instability mode is excited in V-gutter flameholder combustor. As pilot fuel percentage increases, the amplitude of 203Hz mode decreases at equivalence ratio 0.6363 while other modes amplitudes increase first and then decrease. The 130Hz and 203Hz modes are the 2nd and 3rd longitudinal acoustic modes, respectively, based on a one-dimensional combustor acoustic mode analysis.