Combustion Noise Characteristics of Hydrogen-Air Turbulent Lean Premixed Low-Swirl Jet Flames

摘要

Hydrogen-air turbulent lean premixed flames in a low swirl burner are investigated to explore the effect of flame structures on spectral characteristics of direct combustion noise using simultaneous 10 kHz OH-PLIF and sound pressure measurements, as well as PIV-only measurements. The bulk velocities of premixed hydrogen-air mixture at the burner exit plane, V, are 15 and 25 m/s, while an overall equivalence ratio is fixed at 0.45. Direct combustion noise spectra reveal that, with increasing V, pressure of characteristic peaks increases and peak frequencies shift to high-frequency side. Local spectral analyses in OH-PLIF images at V= 15 m/s show a pronounced peak at a frequency corresponding to that in noise spectra, although this trend is not observed for V = 25 m/s. This suggests spectral characteristics of combustion noise are affected by flame structures differently, depending on V.