Pressure dependence of combustion instability for premixed syngas/air in a closed channel

Syngas is a promising alternative energy carrier with low carbon and pollutants emissions, which has huge application potential in internal combustion engines and gas turbines. The combustion characteristics of stoichiometric syngas/air mixtures with varied initial pressure (0.5–2.5 atm) and hydrogen content (10%–90% v/v) were examined through experiments in a rectangular closed channel. The flame images and overpressure dynamics were captured by high-speed schlieren photography and pressure sensors. The flame instabilities and the flame-acoustic wave interaction were explored. The results showed that the flame morphology and dynamics were enhanced with increasing hydrogen content and initial pressure. The Darrius-Landau instability has an impact on flame deformation, which was strengthened with growing initial pressure, while the thermo-diffusive instability could be neglected during combustion. At later stages after tulip inversion, the flame-acoustic wave interaction was relatively outstanding inducing wrinkled flame front and cellular structures on the flame surface.