Dynamics, NO_x and flashback characteritics of confined pre-mixed hydrogen enriched methane flames

The operating regime of a gas turbine combustor is highly sensitive to fuel composition changes. In particular, the addition of hydrogen, a major constituent of syngas, has a major effect on flame behavior due to the higher burning rates associated with hydrogen. A laboratory scale pre-mixed test rig is constructed in order to study such effects. The fuel composition is incremented with increasing hydrogen starting from 100% methane. It is observed that increased RMS pressure levels and higher susceptibility to flashback occurs with increasing hydrogen volume fraction. Furthermore, hydrogen enrichment can cause an abrupt change in the dominant acoustic mode. Phase locked hydroxyl PLIF measurements have been performed with respect to the dominant acoustic instability limit cycle. These measurements are complemented with real time heat release, emissions and flashback measurements. Particular emphasis is put on time resolving the thermoacoustic instability induced flashback cycle of the wedge-shaped flame front and the temporal events associated with flashback.