Modeling and Simulation of Pollutant Formation in Gas Turbines
Technical Thermodynamics
Final Report Abstract
The reduction of pollutant emissions is a fundamental requirement in the design of the newgeneration gas turbine for both electricity production and aeronautical applications. Since regulations on pollutants are extremely stringent, it is necessary to implement aggressive de-sign strategies that allow significant and systematic reductions of emissions. This requires the simultaneous optimization of a large number of components of the gas turbine and investigating each possible configuration with experimental tests is extremely costly and often unfeasible. Computer simulations can have a key role in making the design cycle faster and cost-effective, allowing stronger optimization of the final product. However, this strategy can only be successful if the mathematical models used in the computer simulations are accurate and able to reliably describe the complexity of the product. The state-of-the-arts in the simulation of complex systems involving combustion, dynamics of fluids, and particulate formation is Large Eddy Simulation (LES). This approach is based on a very fine and accurate representation of the gas turbine in the computer simulation and requires accurate description of the physical and chemical processes involved. While we have a good understanding on how to deal with the main combustion process, which is the base of the power generated by the gas turbine, the accuracy in the computation of pollutants produced during and after the combustion process is still not fully satisfactory. In the present project, the effort focused on two important pollutants: (i) carbon oxide and (ii) combustion generated nanoparticles (soot). The former is relevant in stationary gas turbines for electricity production, while the latter is a matter of concern for aircraft engines. The main reason to combine the analysis of this two in the same project is that their mathematical models share strong similarities and can be investigated with analogous approaches. In this project, a systematic approached based on Direct Numerical Simulation (DNS) has been employed. DNS are computer simulations with full-fidelity and provide virtually exact mathematical solutions to the problem. Unfortunately, DNS cannot be applied to real gas turbine configurations due to the enormous computational requirements that would be needed. However, DNS can be used for systems of reduced complexity, that are much smaller and simpler that the real gas turbine but retain the main mechanisms of combustion and pollutant formation. Several of these reduced systems have been successfully designed and simulated with DNS in the present project. These fully detailed solutions obtained with DNS can then be used to gain a precise understanding of the mechanism of pollutant formation and allow the development of better mathematical models that can be then used to simulate real gas turbines.
Publications
- DNS Study of CO Formation in a Staged Gas Turbine Combustor, 12th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements, Montpellier (France), 26 Sep 2018 - 28 Sep 2018
K. Kleinheinz, A. Attili, and H. Pitsch
- Numerically accurate computational techniques for optimal estimator analyses of multi-parameter models, Combustion Theory and Modelling, 22, no. 3, 480–504, 2018
L. Berger, K. Kleinheinz, A. Attili, F. Bisetti, H. Pitsch, and M. E. Mueller
(See online at https://doi.org/10.1080/13647830.2018.1424353) - Experimental and numerical study of soot formation in counterflow diffusion flames of gasoline surrogate components, Combustion and Flame, 210, 159–171, 2019
S. Kruse, A. Wick, P. Medwell, A. Attili, J. Beeckmann, and H. Pitsch
(See online at https://doi.org/10.1016/j.combustflame.2019.08.013) - DNS-driven analysis of the Flamelet/Progress Variable model assumptions on soot inception, growth, and oxidation in turbulent flames, Combustion and Flame, 214, 437 – 449, 2020
A. Wick, A. Attili, F. Bisetti, and H. Pitsch
(See online at https://doi.org/10.1016/j.combustflame.2020.01.012)
