Experimental Study on Combustion Characteristics of Micro-mixing Nozzle Unit Under Pressurized Conditions

Micro-mixing combustion technology is one of the advanced combustion technologies for achieving low pollution emissions and high combustion stability in the combustion chamber of gas turbines. To investigate the effects of the different inlet conditions and burner structures on the characteristics of thermoacoustic model change and pollutant emissions, this paper conducts experiments on the effects of adiabatic flame temperature and thermal load changes on the combustion and NO generation characteristics of syngas-air micro-mixing under 0.4 MPa conditions, targeting two different structures (C1 and C2) of micro-mixing nozzles unit. The results show that the normalized root mean square value of pressure in the combustion chamber is less than 1% under all operating conditions, the phase space trajectory converges to the attractor core, and the recursive graph shows an irregular structure, indicating that the combustion chamber is in a stable combustion state. As the adiabatic flame temperature and thermal load increase, the vibration acceleration amplitude and flame temperature gradually increase. Benefiting from improved mixing uniformity, the C2 structure is more effective than the C1 structure in reducing the enrichment of fuel inside the nozzle and making the temperature field and component concentration field distribution more uniform. When the adiabatic flame temperature is 1400 °C, the NO generation amount decreases from 15.57 μL/L@15%O₂ to 7.43 μL/L@15%O₂. While maintaining the stability of the micro-mixing flame, the C2 structure exhibits excellent stable low emission combustion performance. Therefore, reasonably optimizing the internal structure of the nozzle to enhance fuel-air mixing is an effective technical approach for achieving low NO emission in syngas micro-mixing combustion.