Mesoscale burner Arrays for gas-turbine reheat applications

Mesoscale burner arrays allow combustion to be conducted in a distributed fashion at millimeter (meso) scale. 14 At this scale, diffusive processes are fast, such that a number of advantages over conventional combustion can be achieved without giving up the possibility to use fluid inertia to advantage. Because the scale of the reaction zone follows from the scale at which the reactants are mixed, very compact flames result. We expect that this compact, distributed form of combustion can provide not only the opportunity of interturbine reheat, but also the potential for lean premixed or highly vitiated combustion to suppress NOx emissions. As a proof of concept, a 4 x 4 array with burner elements on 5-mm centers has been fabricated in silicon nitride via shape deposition manufacturing. The array was designed to use gaseous fuel (methane) and swirl stabilization. Results including pressure drop, flame stability, temperature distribution in the burnt gas, and NOx emissions are reported for both a fully premixed (mixing before entry) and partially premixed (mixing in the array) configuration. These results demonstrated the degree to which premixed performance can be achieved with this design and pointed to ways in which the array design could be improved over this first-generation unit.