Effect of Centrifugal Forces on Flame Stability in an Ultra-Compact Combustor

Abstract

The effects of centrifugal forces on flame structure in an Ultra Compact Combustor (UCC) were evaluated computationally. The UCC geometry was modified such that the centrifugal force can be applied as a source term in the momentum equation. This methodology has been validated through the simulation of a centrifuge experiment in which centrifugal forces were found to increase flame speeds. The "bubble transport" mechanism proposed by Lewis was identified in the centrifuge simulations. In hydrogen-air mixture at an equivalence ratio of 0.8, flame speed did not increase until a g loading of 10g 0 , at which point velocity of the buoyant flame packet reached the laminar burning velocity of 1.86 m/s. Further increase in g loading increased the flame speed along with the flame packet. Such "bubble transport" did not occur in UCC simulations. In laminar simulations, the strong velocity perpendicular to the centrifugal forces did not allow the flamelets to accelerate in the direction of buoyancy. Instead, the axial momentum increased and made the flame to become slightly thinner and elongated. In turbulent simulations, the small increase (~10%) in axial velocity did not change the flame structure significantly.

Effect of Mainstream Swirling on Flowfield Characteristics of an Outer-Cavity Trapped Vortex Combustor

“…Recent research indicates that airflow in the cavity region has some characteristics of centrifugal forces and circular motion under swirling flow, which introduces some essential changes to the combustion. Katta et al (2013); Lewis (1971); Lewis et al (1977).…”

Effect of Centrifugal Force on Turbulent Premixed Flames

“…Katta et al [5] have previously investigated this problem. Katta et al [5] have previously investigated this problem.…”

Numerical study of trapped vortex combustors characteristics in small ramjets

“…Their experimental results showed that the rate of combustion can be significantly increased by the centrifugal forces. Katta et al[92] numerically studied the centrifugal force effects on flame structure in an ultra-compact combustor (UCC). In the UCC, a cavity is located circumferentially around the combustor.…”