Experiment on effects of wall cooling with microchannels on performances of swirl combustor

In order to explore the cooling application of microchannels in gas turbine lower emissions combustors, the effects of wall cooling with microchannels on the performances of swirl combustor were studied with water as the coolant. Results showed that the microchannels had significant cooling effect on the combustor walls with high temperature. When Reynolds number of coolant passing through microchannels was less than 350, the increase of Reynolds number of coolant had a significant influence on the decrease of wall temperature, but when Reynolds number was greater than 350, the decrease of wall temperature was almost negligible as the flow rate increased. At fixed values of air mass flow rate and equivalent ratio, the flame structures characterized by CH* chemiluminescence signal hardly changed as Reynolds number of coolant increased, but swirl flame contained yellow sparks or even yellow flame, leading to incomplete combustion in a relatively high Reynolds number. As Reynolds number of coolant increased, the heat transfer rate of wall was raised, which enhanced the interaction between the flame and heat transfer of microchannels during combustion and led to results such as bigger heat loss on the flame surface, more CO emission, less NOx emission and lower overall efficiency of swirl combustion.