Investigation on flame characteristics of industrial gas turbine combustor with different mixing uniformities

Fuel ◽  
2020 ◽  
Vol 259 ◽  
pp. 116297 ◽  
Author(s):  
Zhihao Zhang ◽  
Xiao Liu ◽  
Yaozhen Gong ◽  
Zhiming Li ◽  
Jialong Yang ◽  
...  
Author(s):  
Y. Xia ◽  
A. S. Morgans ◽  
W. P. Jones ◽  
J. Rogerson ◽  
G. Bulat ◽  
...  

The thermoacoustic modes of a full scale industrial gas turbine combustor have been predicted numerically. The predictive approach combines low order network modelling of the acoustic waves in a simplified geometry, with a weakly nonlinear flame describing function, obtained from incompressible large eddy simulations of the flame region under upstream forced velocity perturbations, incorporating reduced chemistry mechanisms. Two incompressible solvers, each employing different numbers of reduced chemistry mechanism steps, are used to simulate the turbulent reacting flowfield to predict the flame describing functions. The predictions differ slightly between reduced chemistry approximations, indicating the need for more involved chemistry. These are then incorporated into a low order thermoacoustic solver to predict thermoacoustic modes. For the combustor operating at two different pressures, most thermoacoustic modes are predicted to be stable, in agreement with the experiments. The predicted modal frequencies are in good agreement with the measurements, although some mismatches in the predicted modal growth rates and hence modal stabilities are observed. Overall, these findings lend confidence in this coupled approach for real industrial gas turbine combustors.


Author(s):  
K. O. Smith ◽  
A. Fahme

Three subscale, cylindrical combustors were rig tested on natural gas at typical industrial gas turbine operating conditions. The intent of the testing was to determine the effect of combustor liner cooling on NOx and CO emissions. In order of decreasing liner cooling, a metal louvre-cooled combustor, a metal effusion-cooled combustor, and a backside-cooled ceramic (CFCC) combustor were evaluated. The three combustors were tested using the same lean-premixed fuel injector. Testing showed that reduced liner cooling produced lower CO emissions as reaction quenching near the liner wall was reduced. A reduction in CO emissions allows a reoptimization of the combustor air flow distribution to yield lower NOx emissions.


Author(s):  
Sebastian Harder ◽  
Franz Joos

The combustion process in a typical can combustor of an industrial gas turbine is determined by the nature of turbulent flow, the chemical reaction and the interaction with each other. Turbulent non-premixed combustion can be divided into different flame regimes in terms of time- and length scales. A typical non-premixed turbulent diffusion flame in a gas turbine combustor covers all regimes. PDF methods are suitable to describe the entire combustion regime without any limitation to a certain regime. In this paper a hybrid pdf/RANS method is presented. The pdf model is based on the transported composition pdf equation, coupled with a commercial three dimensional CFD solver. A stochastic particle system in a Lagrangian framework is used to solve the pdf equation. The chemistry is described by an ILDM approach. The numerical results have been validated with measurements. The test rig consists of an non-premixed gas turbine can combustor with a typical primary and secondary zone. A main air swirler stabilizes the natural gas/air mixture in the primary zone, followed by a burnout and a mixing zone. The setup is investigated using conventional measurement techniques. Field measurements of compositions and mixture fraction as well as temperature are compared with the pdf/RANS calculations. The benefit of this approach is a realistic prediction of all relevant species. The complete one point statistics of the numerical calculations are used to identify the different combustion regimes from the combustor to the exit. The numerical comparison of pdf-, edm- and flamelet-model shows that the pdf approach can be used to describe a realistic gas turbine combustor. In the past, pdf-methods were applied only on simple generic model flames. The purpose of the presented paper is to demonstrate the application of a transported-pdf approach to a realistic gas turbine combustor.


Author(s):  
P. C. T. de Boer

Estimates are given of the burning and evaporation times of No. 2 distillate and No. 6 residual oil droplets, under conditions typical of industrial gas turbine combustors. Account is taken of the temperature dependence of the specific heat, the diffusion constant, and the thermal conductivity of the gas mixture surrounding the droplet. Detailed calculations are presented of the factor by which the droplet lifetime is reduced as a result of convection, for the case that the droplet is released in a gas moving at constant velocity. This factor is on the order of four for the conditions of interest. Using estimates of initial droplet diameter based on data reported by Jasuja, it is found that the ratio of characteristic droplet burning time to characteristic droplet residence time in a typical industrial gas turbine combustor is much smaller than 1 for distillate oil, but may be on the order of 1 for residual oil.


Author(s):  
Masamichi Koyama ◽  
Shigeru Tachibana

This paper explores the technical applicability of a low-swirl fuel nozzle designed for use with a liquid-fueled industrial gas turbine combustor. Particle image velocimetry was applied to measure nozzle flow fields with an open methane-air premixed flame configuration. Herein we discuss the effects of the chamfer dimensions of the nozzle tip on flow characteristics. The profiles indicate parallel shifts in axial direction that depend on chamfer dimensions. When velocity is normalized by bulk velocity and plotted against axial distance from the virtual origins, the profiles are consistent. This means that chamfer dimensions primarily affect the axial position of the flame, while keeping other flow characteristics, such as global stretch rate, unchanged. Then, the atmospheric combustion test was conducted with kerosene in a single-can combustor. Lifted flame stabilization was confirmed by observing the flames through a window. Lastly, an engine test was performed to assess the technical applicability of the fuel nozzle under real engine conditions. The engine testbed was a 290 kW simple-cycle liquid-fueled gas turbine engine. The configurations of the fuel nozzle were consistent with the ones used in the PIV and the atmospheric combustion test. Wall temperatures close to the fuel nozzle exit were within the acceptable range, even without the cooling air required with conventional combustors. This is an advantage of the lifted flame stabilization technique. NOx emissions were below maximum levels set under current Japanese regulations (<84 ppm@15% O2). In sum, the proposed fuel nozzle design shows promise for use with liquid-fueled industrial gas turbine engines.


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