On the use of oscillating jet flames in a coflow to develop soot models for practical applications

Oscillating jet flames in a coflow mimic certain features of turbulent flows in a simplified and controllable way. The potential of the HMOM soot model, which is validated in steady laboratory flames to be applied in practical, mostly turbulent flames, was evaluated. The model accurately predicted all the measurement parameters in a steady laminar sooting jet flame of ethylene/N₂ mixture. When applied to an oscillating flame with the same fuel mixture, results revealed that, while velocity, temperature, and OH fields are well predicted, the peak soot volume fraction is over predicted and occurred away from the experimentally measured location. The potential for soot model improvement was analyzed by correlating the transient gas phase species, PAH, and soot formation or destruction behaviour. The soot number density distribution in mixture fraction space was comparable to the transitional turbulent flame regime dominated by Kelvin-Helmholtz rollers.