Effect of heat release distribution on combustion oscillation

This paper describes the effect of flame position and its spatial variation on prediction accuracy of combustion oscillation in a dry low emission (DLE) combustor. A one-dimensional linear model has been developed. The flame is usually treated as fixed and located at a single axial plane in conventional analysis. However, in practice, the flame position varies during operation. A new flame model considering this variation by a spatial distribution function has been developed. Variation of flame position is empirically measured by using UV images of OH radicals in the oscillating flame. A triangular distribution function is introduced into the flame model because it is similar to the experimentally obtained distribution function. A ‘top-hat’ distribution is also considered to test the influence of distribution shape on the result. Numerical results are compared with experimental data. The triangular flame model shows better prediction of the stability boundaries of combustion oscillation compared with the simple flame sheet model. The results of the top-hat flame model differ from those of the experiment. It is found that consideration of the spatial distribution yields good results for the DLE combustor.