Feedback control block diagram of the combustor instability plant. The combustor instability is represented by a self-excitation loop consisting of a summation block whose output is overall combustor pressure. This is fed to a block representing the flame dynamics, which feeds a block of the acoustics dynamics, which feeds a block that provides a soft limiting function (tan h(x)), which feeds back to the original summation block as the instability pressure. This summation block is also fed with wide band noise and combustor pressure due to fuel control modulation. The overall combustor pressure from before is fed back into a band-pass filter, which feeds the phase shift controller, in turn feeding the fuel valve, which feeds the fuel lines, injector, and combustor, which results in the combustor pressure due to the controlled fuel modulation that ends up feeding the summation block.
Last updated: September 3, 2004 11:01 AM
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