On the Influence of Fuel Distribution on the Flame Structure of Bluff Body Stabilized Flames

Abstract

This paper describes recent learning on the flame structure associated with bluffbody stabilized flames and the influence of the fuel distribution with nonpremixed, jetincrossflow fuel injection. Recent experimental and analytical results disclosing the flame structure are discussed in relation to classical combustion reaction zone regimes. Chemiluminescence and planar fluorescence imaging of OH* radicals as an indicator of the flame zone are analyzed from various tests conducted at Georgia Tech using a twodimensional vanetype bluffbody with simple wallorifice fuel injectors. The results described in this paper support the view that combustion occurs in separated flame zones aligned with the nonpremixed fuel distribution associated with the fuel jets that are very stable and contribute to flame stability at low fuel flow rates. The experimental data is also compared with computational reacting flow largeeddy simulations and interpreted in terms of the fundamental reaction zone regimes for premixed flames. For the conditions of the present experiment, the results indicate combustion occurs over a wide range of flame regimes including the broken reaction zone or separated flamelet regimes.