Effects of inlet air holes on swirl flow characteristics and outlet temperature distribution in an axial swirl combustor

The air inlet holes on the swirl combustor are crucial for high-performance micro gas turbine (MGT), affecting internal airflow, fuel-air mixing, temperature distribution, and cooling. However, there are seldom studies that pay attention to the influence of the air inlet holes coupled with low volatility macromolecular fuels for fast and better fuel-air mixing and combustion processes in MGT. This study investigates the influence of primary and dilution hole positions on airflow, temperature, emissions, and combustion efficiency. Numerical simulations in ANSYS Fluent examine five inlet hole configurations in a two-stage axial swirl combustor. Simulation validation is conducted under three test conditions. The results showed that the cut-off effect of the primary hole affected the size of the swirl vortex core, and the backward movement of the primary hole resulted in a significant increase in the length of the recirculation zone and the coherence high-temperature zone, accelerated the droplet evaporation rate, and reduced CO and NO emissions. Backward movement of dilution hole alters flow field, affecting swirl vortex stability and reflow intensity. Case 3, with original dilution hole and backward extended primary hole, exhibits optimal outlet temperature distribution and combustion efficiency.