Effect of vane angle on combustion characteristics of premixed H2/air in swirl micro-combustors with straight vane or twisted vane

Abstract

The swirler is a key part of the swirl micro-combustor. The swirler vanes affect the flow of the mixture gas entering the combustor channel and change the combustion characteristics of the combustor. The effect of the vane angle on the combustion characteristics in swirl micro-combustors with straight vane (SCSV) or twisted vane (SCTV) was investigated and compared under different inlet velocities, equivalence ratios, and wall materials. The results show that increasing the vane angle expands the corner recirculation zone (CRZ) of SCSV and the inner recirculation zone (IRZ) of SCTV. The expansion of recirculation zone improves the combustion stability by anchoring the flame at high inlet velocities. The effect of vane angle on the wall temperature is different for SCSV and SCTV. When the inlet velocity is 40 m/s, the mean outer wall temperature rises by 47 K in SCSV and drops by 30 K in SCTV as the vane angle increases from 15° to 75°. In SCTV with SiC as the wall material, the large vane angle improves the preheating effect, and the heat transferred to the mixture gas (Qpre) is greater by 13.6% at a vane angle of 75° compared to 15°. At high inlet velocities, the vane angle of the swirler has a significant effect on the combustion efficiency and pressure loss. When the inlet velocity is 40 m/s, the combustion efficiency and total pressure loss coefficient of SCSV are 97% and 1.9%, 97.7% and 2.8%, 97.3% and 8.3% at vane angles of 15°, 30°, 75°, respectively.