Flashback Characteristics in CH4/H2-air Premixed Swirl-stabilized Combustion
In the context of stringent requirement of energy efficiency and carbon neutrality,there is an increasingly growing trend towards utilizing hydrogen-enriched fuel blend in gas turbine combus-tors.Introducing hydrogen into the fuel increases the likelihood of flashback during the combustion process,necessitating further investigation.In this research,a premixed bluff-body swirl burner is chosen for numerical simulations of premixed CH4/H2-air combustion under various operating con-ditions.SST k-ω model and Flamelet-Generated Manifold(FGM)are employed,respectively,as turbulence model and combustion model.It is of great importance to accurately calculate turbu-lent flame speed in order to predict flashback,thus the influence of hydrogen addition on laminar flame speed is considered when concerning the closure of the source term in the transport equation of the progress variable.The numerical models and methods are verified against experimental re-sults.Furthermore,the impact of three key factors on flashback are investigated:equivalence ratio,inlet velocity,and thermal boundary conditions of the bluff-body.Results show that decreasing equivalence ratio,increasing inlet velocity,or enhancing heat transfer at bluff-body wall tend to alleviate the occurrence of flashback.The obtained insight could potentially guide the design of hydrogen-enriched gas turbine combustor.
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