Flow characteristics in non-conventional combustion chamber configurations

Abstract

Flow characteristics in combustion chambers of several non-circular cross-sectional configurations were numerically investigated. Different cross-sectional configurations including annular and multi-sector annulus configurations with different fillets were proposed, examined, and compared to the conventional circular arrangement. A numerical model was established and validated against other findings. The model was then used to study the effects of different design parameters including convex and fillet radii as well as some operational parameters such as the angular velocity on the total pressure drop and the secondary flow characteristics like swirl number, secondary vortex intensity, and helicity. Results revealed the optimum number of annulus sectors to be six, at which the highest hydraulic diameter was achieved for the same cross-sectional area. Optimum values of the inner and outer corner fillets were also obtained. Several valve arrangements were also investigated to achieve the highest possible valve area ratio for the proposed configurations. One of the proposed configurations, which incorporates six annular chambers with filleted corners with a hydraulic diameter ratio of 0.991 compared to the conventional circular design, denoted AFC4, achieved a more compact design while maintaining very comparable flow characteristics to those of the circular design. Although it needs more thorough investigations, it could present a viable alternative design option for combustion chambers.