Ignition Limits and Light-Around of Lean Hydrogen-Methane Flames in A Spinning Annular Combustor (GT2026-177740)

Abstract

Ignition and light-around of lean hydrogen-methane flames was investigated in an atmospheric annular combustor which consists of six equally spaced injectors oriented tangentially to the annulus. This produces flames and flows that are predominantly in the azimuthal direction known as the Spinning Combustion Technology (SCT). Ignition limits and characteristic light-around times were investigated across a range of operating conditions to understand the main mechanisms governing the light-around times under fully premixed injection conditions. The effect of bulk velocity, equivalence ratio, H2 volume fraction from 0 to 100% and effusion cooling were measured and characterised using highspeed flame imaging and an array of photomultipliers with OH* filters. For each operating condition, 25 runs were performed to ensure repeatability resulting in a large dataset that includes 2450 ignition sequences. Results show that both the mean azimuthal velocity Uθ as well as changes in flame speed SL and thermal expansion ratio ρu/ρb of the fuel mixture affect the light-around time. However, overlapping measurements with experiments conducted by replacing the injectors with premixed bluff body axially oriented injectors shows that the light-around time for the SCT configuration is almost twice as fast which is attributed to the bulk swirl induced by the SCT burner orientation. Finally, it is demonstrated that the level of effusion cooling increases light-around times and reduces the ignition limits. These results validate the SCT with reduced light-around times and extended lean ignition limits.