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The present work proposes a novel concept for a sequential burner and combustor that can be located downstream of a first stage combustor or downstream of a turbine stage in the case of a reheat gas turbine. The novel aspect is the method of flame anchoring, which, instead of relying on dump expansion as in the present state-of-the-art, relies on setting up a static temperature gradient through the premixing and flame zones. The advantage of this is that anchoring of the auto-igniting flame is not dependent on fluid mechanic phenomena, and reaction can proceed at rates governed by the chemical kinetics. Under these circumstances, CO can reach its equilibrium in ≪ 1ms, which allows for compactness and the potential of single digit NOx emissions at hot gas temperatures in excess of 2100K. Pressure loss is a critical aspect, as the concept requires flows to be accelerated to high velocities (M∼0.7). However, it is shown that pressure losses can be limited to 4–5%. The concept is evaluated through analytical and 1D approaches, while the feasibility of achieving a design that meets the desired turbulence characteristics at an acceptable pressure loss is demonstrated by way of 3D CFD. |
