Design and Evaluation of a Trapped Vortex Lean Direct Injection Combustor

Abstract

This project investigates the design of a lean direct injection (LDI) combustor targeting reduced NOx emissions while maintaining complete fuel burnout and stable combustion. Lean combustion is known to reduce NOx through lower flame temperatures, however, it introduces challenges in mixing, vaporization, and flame stability. Multiple combustor geometries were designed, sized using literature-based residence time estimates, and evaluated using CFD. Results guided iterative resizing, design improvements, and ultimately down selection to one design. This final design implemented a trapped vortex design and a prototype was manufactured and evaluated by testing. Results of ths evaluation demonstrate that while the trapped vortex design may be effective at producing increased resonance time in a short area, improvements must be made to aid mixing and flow direction into the trap such that a lean burn may be achieved uniformly across the combustion zone without un-combusted reactants escaping.