Swirling flowfield for colorless distributed combustion

Abstract

Distributed combustion has been shown to provide significant improvements of gas turbine combustors performance including uniform thermal field in the entire combustion chamber (improved pattern factor), ultra-low emission of NOx and CO, low noise, enhanced stability and higher efficiency. The flowfield associated with swirl is investigated to seek colorless distributed combustion. Non-reacting Particle Image Velocimetry (PIV) diagnostics is employed to determine the flow field characteristics of three different configurations with focus on velocity distribution, flow entrainment of reactive species, and turbulence. In all the configurations, air was injected tangentially into the combustor. The results for the configurations reported here represent both non-swirling “linear” flow and swirling flow. Results showed that swirling flowfield configuration is characterized by higher flow velocities and much enhanced entrainment ratios throughout the combustor as compared to non-swirling case. Swirling flow exhibited high velocity region at the core of the combustor to further promote mixing and entrainment of reactive species. Higher velocities and entrainment are of significant importance in distributed combustion to prevent flame anchoring and enhance mixing. Experimental results are compared with numerical simulation for seeking improved flow distribution. The flowfield for different configurations are integrated with earlier data on emissions that showed near zero emission for swirling distributed combustion in gas turbine combustors.