An experimental study on the effect of swirl number on pollutant formation in propane bluff-body stabilized swirl diffusion flames

Abstract

The combustion characteristics of propane/air bluff-body stabilized swirl diffusion flames within the turbulent regime are studied experimentally to determine the effect of the swirl number on the flame dynamics and pollutant emissions. The investigated burner consists of a central bluff body with an annulus to introduce the tangential and axial air flows. Results show that in low annulus Reynolds numbers (ReS), the temperature distribution is more affected by the overall equivalence ratio (φo), which is calculated based on the flow rates of the air supplies and the fuel jet. However, by increasing ReS, the impact of swirl number becomes more apparent. Analysis of the combustion products demonstrates a reduction in CO concentration with increasing the geometric swirl number which becomes more evident in higher annulus Reynolds numbers. In addition, the trend of NO emission is strongly analogous to the temperature distribution which is an indication of thermal NO formation. Measurements demonstrate that in lower annulus Reynolds numbers, the dominant factor is the overall equivalence ratio, while with increasing the annulus Reynolds number, the swirl number represents more significance.

Uncertainty quantification analysis of Reynolds-averaged Navier–Stokes simulation of spray swirling jets undergoing vortex breakdown

“…The injection flow rate of the gaseous phase is kept constant, fixing a bulk Reynolds number, R e 0 = 2 U b u l k R / ν = 6000, that corresponds to a configuration of technological interest as concerns swirl-stabilized combustors. 46,47 A nearly-saturated condition is prescribed for the air-acetone vapor mixture at the inflow section, i.e., S * = Y v / Y v , s = 0.99, where S * is the saturation, Y v is the actual vapor mass fraction on the inflow section and Y v , s false( p 0 , T 0 false) is the vapor mass fraction in fully-saturated condition, evaluated at the inflow temperature and pressure. The acetone-to-air mass flow rate ratio is set to normalΨ = m ˙ a c t / m ˙ a i r = 0.28, with m ˙ a c t = m ˙ a c t , l + m ˙ a c t , v being the sum of liquid and gaseous acetone mass flow rates.…”

Investigation on combustion characteristics and emissions of biogas/hydrogen blends in gas turbine combustors

“…Research studies have presented several important parameters that influence combustion instability characteristics in gas turbines: the swirl number, equivalence ratio, combustion design, and fuel compositions. Jalalatian et al [23] have performed experiments on the effect of the swirl number, equivalence ratio, and Reynolds numbers on diffusion flame structure and pollutant emissions. They demonstrated that when the overall equivalence ratio (the global equivalence ratio) increases, the flame length enhances, increase in swirl number leads to a slight decrease in temperature, CO concentrations, and NO thermal concentrations.…”