| Popis: |
§** †† This paper describes a method for detecting and preventing lean blow out (LBO) in a premixed, swirl stabilized combustor. The acoustic signal is filtered to detect localized extinction ‘events’, which increase in frequency as the flame equivalence ratio, φ, approaches the LBO limit, φ φ φ φLBO. As the flame becomes leaner, φLBO can be effectively shifted to lower equivalence ratios by redirecting a fraction of the total fuel into a central, premixed pilot. This actuation can increase the equivalence ratio in the stabilization region at a constant power setting and counter the flame lift associated with LBO. The resulting control system maintains lean flame stability in the presence of flow fluctuations. The combustor can therefore operate with an improved safety margin at lower temperatures and less NOx (nitrous oxides) emissions. |
