LAUSR

ABSTRACT The combustion characteristics of dimethyl ether (DME) in a partially premixed tubular flame burner have been investigated numerically. The species distribution, stability limit of tubular flame, wall temperature and burn-off rate have been studied at different equivalence ratios and inlet velocities. Meanwhile, the corresponding combustion characteristics in the rapidly mixed tubular flame burner have been simulated and compared. The results show that the partially premixed burner forms a unique species distribution and the fuel and the oxidant are not mixed uniformly. This unique species distribution will promote the chemical enthalpy supply to the flame front by recirculation reverse flow in the center, and thus strengthen the combustion process. Based on this unique species distribution, the partially premixed burner has larger tubular flame stability limit, lower heat loss, and higher burn-off rate, especially for lean operating conditions. Comparing the formation mechanisms of the tubular flames in two types of burners, it is found that the partially premixed burner forms partially premixed tubular flame, which is no need to create a uniform premixed gas zone, thereby suppressing the influence of velocity difference between fuel and oxidant present in the rapidly mixed burner.