By taking a micro gas turbine combustor as the example

the angle of swirl nozzles was changed to increase the swirl strength and numerical simulation was carried out to investigate the swirl combustion characteristics

through comparison of swirl strength in main combustion zone and that in pilot zone. The results show that

with an increase in swirl strength of the main combustion zone

the recirculation zone area increases dramatically

the fuel and air mixes uniformly and burns quickly. However

once the swirl strength in main combustion zone increases to a certain degree

the circulation zone will affect the air flow at the combustor outlet

which goes against the flow field's stability

so there must be an optimal swirl angle which can gain a perfect combustion effect. Changes in swirl strength in pilot zone affect little on the flow field during combustion.