This paper systematically develops a high-fidelity turbulent combustion surrogate model using deep learning.We construct a surrogate model to simulate the turbulent combustion process in real time,based on a state-oft...This paper systematically develops a high-fidelity turbulent combustion surrogate model using deep learning.We construct a surrogate model to simulate the turbulent combustion process in real time,based on a state-ofthe-art spatiotemporal forecasting neural network.To address the issue of shifted distribution in autoregressive long-term prediction,two training techniques are proposed:unrolled training and injecting noise training.These techniques significantly improve the stability and robustness of the model.Two datasets of turbulent combustion in a combustor with cavity and a vitiated co-flow burner(Cabra burner)have been generated for model validation.The effects of model architecture,unrolled time,noise amplitude,and training dataset size on the long-term predictive performance are explored.The well-trained model can be applicable to new cases by extrapolation and give spatially and temporally consistent results in long-term predictions for turbulent reacting flows that are highly unsteady.展开更多
A detailed chemical mechanism to describe the combustion of natural gas in internal combustion （IC） engine has been developed,which is consisting of 233 reversible reactions and 79 species.This mechanism accounts fo...A detailed chemical mechanism to describe the combustion of natural gas in internal combustion （IC） engine has been developed,which is consisting of 233 reversible reactions and 79 species.This mechanism accounts for the oxidation of methane,ethane,propane and nitrogen.It has been tested using IC engine model of CHEMKIN 4.1.1 and experimental measurements.The performance of the proposed mechanism was evaluated at various equivalence ratios （φ=0.6 to φ=1.3）,initial reactor conditions （Tini=500 to 3500 ℃; Pini=1.0 to 10 atm） and engine speed （2000-7000 rpm）.The proposed kinetic mechanism shows good concordances with GRI3.0 mechanism especially in the prediction of temperature,pressure and major product species （H2O,CO2） profiles at stoichiometric conditions （φ=1.0）.The experimental results of measured cylinder pressure,species fractions were also in agreement with simulation results derived from the proposed kinetic mechanism.The proposed mechanism successfully predicts the formation of gaseous pollutants （CO,NO,NO2,NH3） in the engine exhaust.Although there are some discrepancies among each simulation profile,the proposed detailed mechanism is good to represent the combustion of natural gas in IC engine.展开更多
Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism h...Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism have been constructed with the analysis of the rate sensitivity matrix f (PCAF method), and the computational singular perturbation (CSP). The analysis was performed on solutions of unstrained adiabatic premixed flames with detailed chemical kinetics described by GRI 3.0 for methane including NOx formation. A 9-step reduced mechanism for methane has been constructed which reproduces accurately laminar burning velocities, flame temperatures and mass fraction distributions of major species for the whole flammability range. Many steady-state species are also predicted satisfactorily. This mechanism is especially for lean flames. This mechanism is accurate for a wide range of the equivalence ratio (1, 0.9, 0.8, and 0.7) and for pressures as high as 40 atm to 60 atm. For both fuels, the CSP algorithm automatically pointed to the same steady-state species as those identified by laborious analysis or intuition in the literature and the global reactions were similar to well established previous methane-reduced mechanisms. This implies that the method is very well suited for the study of complex mechanisms for heavy hydrocarbon combustion.展开更多
The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Eff...The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Effects of the flow ex-pansion and compression on the cellular detonation cell were investigated to illus-trate the mechanism of the transverse wave development and the cellular detona-tion cell evolution. By examining gas composition variations behind the leading shock,the chemical reaction rate,the reaction zone length,and thermodynamic parameters,two kinds of the abnormal detonation waves were identified. To explore their development mechanism,chemical reactions,reflected shocks and rarefac-tion waves were discussed,which interact with each other and affect the cellular detonation in different ways.展开更多
The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numer...The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numerical study on the use of a methane flame to produce acetylene.A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames.The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures,and these were compared to numerical results from Computational Fluid Dynamics(CFD)simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function(RANS-PDF)approach coupled with detailed chemical mechanisms.The Leeds 1.5,GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms.The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied.The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane.Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6.Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time.So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.展开更多
基金support from the National Natural Science Foundation of China(Grant No.52250710681 and 52022091)Support from the UK Engineering and Physical Sciences Research Council under the project“UK Consortium on Mesoscale Engineering Sciences(UKCOMES)”(Grant No.EP/X035875/1)is also acknowledged.
文摘This paper systematically develops a high-fidelity turbulent combustion surrogate model using deep learning.We construct a surrogate model to simulate the turbulent combustion process in real time,based on a state-ofthe-art spatiotemporal forecasting neural network.To address the issue of shifted distribution in autoregressive long-term prediction,two training techniques are proposed:unrolled training and injecting noise training.These techniques significantly improve the stability and robustness of the model.Two datasets of turbulent combustion in a combustor with cavity and a vitiated co-flow burner(Cabra burner)have been generated for model validation.The effects of model architecture,unrolled time,noise amplitude,and training dataset size on the long-term predictive performance are explored.The well-trained model can be applicable to new cases by extrapolation and give spatially and temporally consistent results in long-term predictions for turbulent reacting flows that are highly unsteady.
文摘A detailed chemical mechanism to describe the combustion of natural gas in internal combustion （IC） engine has been developed,which is consisting of 233 reversible reactions and 79 species.This mechanism accounts for the oxidation of methane,ethane,propane and nitrogen.It has been tested using IC engine model of CHEMKIN 4.1.1 and experimental measurements.The performance of the proposed mechanism was evaluated at various equivalence ratios （φ=0.6 to φ=1.3）,initial reactor conditions （Tini=500 to 3500 ℃; Pini=1.0 to 10 atm） and engine speed （2000-7000 rpm）.The proposed kinetic mechanism shows good concordances with GRI3.0 mechanism especially in the prediction of temperature,pressure and major product species （H2O,CO2） profiles at stoichiometric conditions （φ=1.0）.The experimental results of measured cylinder pressure,species fractions were also in agreement with simulation results derived from the proposed kinetic mechanism.The proposed mechanism successfully predicts the formation of gaseous pollutants （CO,NO,NO2,NH3） in the engine exhaust.Although there are some discrepancies among each simulation profile,the proposed detailed mechanism is good to represent the combustion of natural gas in IC engine.
文摘Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism have been constructed with the analysis of the rate sensitivity matrix f (PCAF method), and the computational singular perturbation (CSP). The analysis was performed on solutions of unstrained adiabatic premixed flames with detailed chemical kinetics described by GRI 3.0 for methane including NOx formation. A 9-step reduced mechanism for methane has been constructed which reproduces accurately laminar burning velocities, flame temperatures and mass fraction distributions of major species for the whole flammability range. Many steady-state species are also predicted satisfactorily. This mechanism is especially for lean flames. This mechanism is accurate for a wide range of the equivalence ratio (1, 0.9, 0.8, and 0.7) and for pressures as high as 40 atm to 60 atm. For both fuels, the CSP algorithm automatically pointed to the same steady-state species as those identified by laborious analysis or intuition in the literature and the global reactions were similar to well established previous methane-reduced mechanisms. This implies that the method is very well suited for the study of complex mechanisms for heavy hydrocarbon combustion.
文摘The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Effects of the flow ex-pansion and compression on the cellular detonation cell were investigated to illus-trate the mechanism of the transverse wave development and the cellular detona-tion cell evolution. By examining gas composition variations behind the leading shock,the chemical reaction rate,the reaction zone length,and thermodynamic parameters,two kinds of the abnormal detonation waves were identified. To explore their development mechanism,chemical reactions,reflected shocks and rarefac-tion waves were discussed,which interact with each other and affect the cellular detonation in different ways.
基金Supported by the National Natural Science Foundation of China(20976090)the Foundation for the Author of National Excellent Doctoral Dissertation of China(200757)
文摘The partial oxidation of hydrocarbons is an important technical route to produce acetylene for chemical industry.The partial oxidation reactor is the key to high acetylene yields.This work is an experimental and numerical study on the use of a methane flame to produce acetylene.A lab scale partial oxidation reactor was used to produce ultra fuel-rich premixed jet flames.The axial temperature and species concentration profiles were measured for different equivalence ratios and preheating temperatures,and these were compared to numerical results from Computational Fluid Dynamics(CFD)simulations that used the Reynolds Averaged Navier-Stokes Probability Density Function(RANS-PDF)approach coupled with detailed chemical mechanisms.The Leeds 1.5,GRI 3.0 and San Diego mechanisms were used to investigate the effect of the detailed chemical mechanisms.The effects of equivalence ratio and preheating temperature on acetylene production were experimentally and numerically studied.The experimental validations indicated that the present numerical simulation provided reliable prediction on the partial oxidation of methane.Using this simulation method the optimal equivalence ratio for acetylene production was determined to be 3.6.Increasing preheating temperature improved acetylene production and shortened greatly the ignition delay time.So the increase of preheating temperature had to be limited to avoid uncontrolled ignition in the mixing chamber and the pyrolysis of methane in the preheater.
