Evaluation of Combustion Flow Characteristics of a Lean-Burn Trapped Vortex Combustor with Various Cavity Guide Vane Structures

The present study focuses on analyzing the effects of variations in the cavity guide vane structure on the performance of a trapped vortex combustor. Steady, 2D reactive and non-reactive flow numerical simulations were carried out for a trapped vortex combustor fitted with a cavity guide vane. Three cases were introduced, namely, a) the combustor with rectangular guide vane and squared edges, b) the rectangular guide vane with rounded edges, and c) streamlined guide vane with rounded edges. Non-reactive flow cases were considered at the air velocities of 20, 30, and 40 m/s. In reactive- flow cases, the equivalence ratio is maintained with 20% excess air as 0.8. Mass entrainment into the cavity and pressure loss across the combustor are used to evaluate the effectiveness of cavity guide vane. The rectangular guide vane with rounded edges of combustor performs well in terms of the mass entrainment and the vortex structure. A peak direct mass entrainment of 3.8 kg/s was obtained for the mainstream air velocity of 40 m/s. The rectangular guide vane with rounded edges possess the superior flow and combustion characteristics at all velocities. It has been observed that the cavity guide vane structure optimization plays an important role in determining the total flow into the cavity and the number and strength of vortices formed inside the cavity.