Reduced Methane Combustion Mechanism and Verification, Validation, and Accreditation (VV&A) in CFD for NO Emission P
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https://doi.org/10.1007/s11630-020-1321-3
Article ID: 1003-2169(2020)00-0000-00
Reduced Methane Combustion Mechanism and Verification, Validation, and Accreditation (VV&A) in CFD for NO Emission Prediction SUN Jihao, ZHANG Zhihao, LIU Xiao*, ZHENG Hongtao College of Power and Energy Engineering, Harbin Engineering University, Nantong 150001, China © Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: In order to obtain a reduced methane combustion mechanism for predicting combustion field and pollutants accurately in CFD simulations with a lower computational cost, a reduced mechanism with 22 species and 65 steps of reactions from GRI-Mech 3.0 was obtained by direct relation graph method and sensitivity analysis. The ideal reactor calculation and VV&A (Verification, Validation, and Accreditation) in CFD were carried out using the proposed mechanism. The results showed that the proposed mechanism agrees well with the detailed mechanism in a wide range of operating conditions; the temperature field and species can be predicted accurately in CFD simulations (RANS and LES models), and the NO prediction error of an industrial gas turbine combustor outlet is less than 210–6. The proposed mechanism has high engineering values.
Keywords: mechanism reduction, pollutant emissions, direct relation graph method, sensitivity analysis, numerical simulation
1. Introduction Serious environmental problem and challenge of decreasing pollutant from gas turbine engines have received more and more attention by researchers. With the development of combustion technology, the emissions of pollutant such as CO and Unburned Hydrocarbon (UHC) can be reduced to a very low level. Because the gas turbine combustor works under high temperature and high pressure, NOx becomes a pollutant difficult to control [1]. Therefore, reducing NOx emission has become the focus of advanced low-pollution combustor design, and accurate prediction of NOx is important during the design process. Using Computational Fluid Dynamics (CFD) to predict the field structure and pollutant generation of combustion requires a relatively detailed and accurate chemical reaction mechanism [2]. However, it will make Received: May 11, 2019
AE: TONG Huiling
the computational CPU time very large when the detailed mechanism is coupled directly in CFD simulation [3]. At the same time, multiple time-scale reactions contained in the detailed mechanism often cause the “stiff” problem, which makes the simulation difficult to converge. Therefore, the detailed mechanism needs to be reduced, and the combustion process should be predicted accurately with lower computational cost [3] as well. Reduced mechanisms were obtained using different methods based on different respective concerns. For the reduced reaction mechanism of methane, Peters et al. [4] constructed the oxidation process of methane into a complete reaction path consisted of 14 species and 18 steps of reactions in 1987, and it was furtherly redu
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