CFD simulation and validation of hydrodynamic instabilities onset in swirl combustors

The objective of this paper is to employ a numerical approach to model a 150kW tangential swirl burner to investigate the consequence of central air injection on the flashback mechanism. The effects of diffusive air injection on flow field characteristics and how these can affect the lower instability limits by altering the flashback mechanism via CIVB are analysed in both experimental and theoretical approaches. Simulations under isothermal conditions are carried out using both premixed and partially premixed species models to compare the flow field behaviour with and without air injection. The experimental data includes LDA measurements for the same burner geometry. CFD and experimental results demonstrated that using diffusive air affects flashback propensity significantly by expanding the stability region in terms of both equivalence ratio and mass flow rate that lead to greater operability at higher power outputs compared to using only a central body injector. The CFD results were verified and correlated to experimental findings with very good agreement