The effects of inert diluents in the fuel mixture of a model swirl stabilized gas turbine com-bustor, under thermoacoustically unstable limit cycle operation, were studied experimentally.The measurements included Particle Image Velocimetry (PIV), high speed CH∗chemilumines-cent imaging and dynamic pressure signals. The paper focuses on the dynamic phenomenon ofthe period doubling bifurcation, which came about when the equivalence ratio (φ) of undilutedflames was enriched from 0.55 to 0.60 under constant Reynolds number (Re). The bifurcationfeatured an emergence of an aerodynamically related timescale in addition to the fundamentaltimescale which was induced from an unstable acoustic eigenmode. The aerodynamic timescaleis introduced by azimuthal convection of a high heat release rate region, and is linked in theliterature with a precessing motion of the recirculation zone. Prior to the bifurcation, theflame anchored between the wall and the outer shear layers of the recirculation zone assuminga V-shape. The dynamics were attracted to a Period-1 limit cycle. Post the bifurcation the flameexpanded in the inner shear layers of the recirculation zone assuming an M-shape, while thedynamics were attracted to a Period-2 limit cycle. The latter operational condition was subjectto nitrogen dilution in order to parametrically increase the molar fraction of inert diluent inthe fuel stream. It was found that on increasing the diluent molar fraction the amplitude andthe frequency of the limit cycle fundamental acoustic mode decreased. Also, inert dilution sup-pressed the aerodynamic timescale and the flame assumed a V-shape again. A mechanism tointerpret this mechanism is suggested. Increasing the diluent molar fraction of the fuel makesthe flame susceptible to quenching because the extinction strain rate of the mixture decreased.Thus, the flow imposed strain rates quenched the flame when it attempted to anchor on theinner shear layers of the vortex breakdown induced recirculation zone. The inability of theflame to anchor on the shear layers suppressed the aerodynamic mode. The paper argues thatthe existence of inert diluents in the fuel can significantly alter the dynamic state of the com-bustor, since the anchoring locations of the flame greatly depend on the composition-sensitiveextinction strain rate of the mixture.