Numerical study on three-stage ignition of dimethyl ether by hot air under engine-relevant conditions

Chen, Xinyi1; Li, Zisen1; Wang, Yiqing1; Han, Wang2; Scholtissek, Arne2; Dai, Peng3; Hasse, Christian2; Chen, Zheng1

2023-09-01

10.1080/13647830.2023.2261423

COMBUSTION THEORY AND MODELLING   Impact Factor & Quartile

1364-7830

1741-3559

Non-premixed combustion often occurs in practical engines, and it is affected by the coupling effects of chemical kinetics and transport. This study aims to elucidate the individual effect of chemical kinetics, molecular diffusion, and convective transport on non-premixed combustion. To this end, three types of reactive systems are investigated by numerical simulations considering detailed chemistry and transport: (1) thermochemical system: 0D homogeneous autoignition, (2) thermochemical-diffusive system: 1D non-premixed ignition in a static diffusion layer, (3) thermochemical-diffusive-convective system: 1D non-premixed ignition in a counterflow and 2D lifted flame in a coflow. The simulations are carried out for diluted dimethyl ether and hot air under engine-relevant conditions with a pressure of 40 atm and hot air temperatures of 700 & SIM;1500 K. First, homogeneous ignition process of DME/air premixture is investigated. It is found that, apart from the low- and high-temperature chemistry which are essential in the typical two-stage ignition, the intermediate-temperature chemistry can also play an important role, especially for slow reaction process in fuel rich regions. Then, the effects of thermochemical conditions and molecular diffusion are assessed for non-premixed ignition process in the 1D diffusion layer. The results show that, the reaction front always initiates from local autoignition in most reactive regions; then it propagates either in sequential auto-ignition mode or in diffusion-driven mode as a deflagration wave. With various thermochemical conditions, the chemical kinetics behave differently and produce complex multibrachial (tetrabrachial, pentabrachial and hexbrachial) structures during the reaction front propagation. Decreasing the diffusion layer thickness generally delays the reaction front initiation but enhances its transition into a diffusion-driven flame. Finally, it is shown that 1D diffusion layer simulations can qualitatively reproduce the complex multibrachial structures in 1D counterflow and 2D coflow at certain conditions. A regime diagram is proposed to separate the effects of chemical kinetics, molecular diffusion, and convective transport.

non-premixed combustion dimethyl ether three-stage ignition intermediate-temperature chemistry

SCI

English

Others

National Natural Science Foundation of China["52176096","51861135309"] ; German Research Foundation (DFG)[411275182]

Thermodynamics ; Energy & Fuels ; Engineering ; Mathematics

Thermodynamics ; Energy & Fuels ; Engineering, Chemical ; Mathematics, Interdisciplinary Applications

WOS:001071542800001

TAYLOR & FRANCIS LTD

Web of Science

1.Peking Univ, Coll Engn, Dept Mech & Engn Sci, SKLTCS,CAPT,BIC EAST, Beijing, Peoples R China
2.Tech Univ Darmstadt, Inst Simulat react Thermofluid Syst, Darmstadt, Germany
3.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen, Peoples R China

Chen, Xinyi,Li, Zisen,Wang, Yiqing,et al. Numerical study on three-stage ignition of dimethyl ether by hot air under engine-relevant conditions[J]. COMBUSTION THEORY AND MODELLING,2023.

Chen, Xinyi.,Li, Zisen.,Wang, Yiqing.,Han, Wang.,Scholtissek, Arne.,...&Chen, Zheng.(2023).Numerical study on three-stage ignition of dimethyl ether by hot air under engine-relevant conditions.COMBUSTION THEORY AND MODELLING.

Chen, Xinyi,et al."Numerical study on three-stage ignition of dimethyl ether by hot air under engine-relevant conditions".COMBUSTION THEORY AND MODELLING (2023).