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A cost-effective calculation method for self-excitation of gas oscillations in low-emission combustors of gas turbine units is developed. The method is based on the shear stress transport scale-adaptive simulation (SAS SST) turbulence model and the turbulent combustion model with a modified equation for a variable combustion completeness. A multiplier associated with gas pressure oscillations is introduced into the source term of this equation. The tendency of the combustor to excite gas oscillations is estimated by two parameters: the exponent of this multiplier (interaction index) and the logarithmic decrement of oscillation damping. Within the framework of the solution to a problem of self-excitation of oscillations in the case of a specified homogeneous methane–air mixture at the combustor inlet, there is the first radial oscillation mode with a frequency of 2700 Hz. In the case of separate air and fuel supply to the combustor, there is the first longitudinal oscillation mode with a frequency of 300 Hz. The use of resonant absorbers (small anti-oscillation screens) makes it possible to completely suppress radial oscillations. [ABSTRACT FROM AUTHOR]

An economical method for numerical simulation of self-excitation of gas oscillations in low-emission combustors of gas turbine plants is developed and tested. The method is based on using an SAS SST turbulence model and a turbulent combustion model with a modified equation for a variable degree of combustion completion. Simulating the self-excitation of gas oscillations requires that a factor associated with gas pressure oscillations is introduced into the source term of this equation. Isolation of one of the gas oscillation modes prone to self-excitation is carried out using a resonant filter operating in each cell of the computational domain. The computational results obtained using the proposed method make it possible to study the effect of design measures and operating parameters of self-oscillations and to approach the choice of measures to suppress them. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the hydrodynamic and physicochemical characteristics of flow and combustion in a low-emission combustor (LEC) that differs from other combustors in design and lean fuel–air combustion modes. The influence of the composition and residence time of the mixture in the LEC on NO and CO emissions is considered. A LEC operation concept and demonstrator have been developed that provide NO and CO emissions below 5 ppm, which is 2–5 times lower than that in available LECs. The results of experimental studies of the LEC demonstrator with varying flame temperature, pressure, and residence time in the LEC confirm the validity of the proposed solutions. [ABSTRACT FROM AUTHOR]