The effect of toroidal geometrical shape on turbulent oscillations in a bidirectional vortex combustor

Abstract

The paper reports on detailed studies of a bidirectional swirling flow structure in a toroidal vortex chamber under non-reactive and combustion conditions at the Reynolds numbers Re = 65,000 and Re = 10,000. The explanation of reduced velocity fluctuations near the head wall compared to simple cylindrical bidirectional chambers is also given. The studies were carried out using transient numerical simulations DES (Detached Eddy Simulation). The necessary experimental validation based on PIV (Particle Image Velocimetry) and temperature measurements were performed as well. The results show that fluctuations of all velocity components in the toroidal part of the chamber do not exceed 20% in non-reactive conditions and 10% in the combustion case. Additionally, temperature oscillations are less than 10% of the adiabatic stoichiometric temperature of propane-air mixture combustion. The studies of combustion at different equivalence ratios show that the rich combustion ϕ = 1.5 provides the most favorable conditions in terms of mixture ignition. Moreover, a large-scale backflow structure is formed beyond the outlet nozzle at rich modes that leads to an increase in combustion stability. This feature can be usefully applied in studies of mesoscale bidirectional arrays and developing multiport combustion chambers.