PREMIXING FUEL INJECTOR AND METHOD OF OPERATION

A premixing fuel injector for an industrial gas turbine engine includes an axially extending centerbody (58) and a pair of radially offset scrolls (18) bounding a mixing chamber (24). The leading end (28) of each scroll cooperates with the trailing end (34) of the neighboring scroll to define an intake slot (42) for admitting a stream of primary combustion air (44) tangentially into the mixing chamber. Fuel injection passages extend along each intake slot for injecting jets (76a, 76b) of primary fuel into the incoming airstream (44). The injector is operable in a prescribed or normal state, and in a degraded state associated with the presence of undesirable combustion inside the mixing chamber. The fuel injection passages are oriented and positioned so that the fuel jets issuing therefrom are ineffective at sustaining the undesirable combustion for more than a limited interval of time. In one embodiment of the invention, the injection passages are positioned so that the trailing end (34) of the neighboring scroll acts as a physical barrier to limit radial penetration of the fuel jets when the injector operates in the degraded state.