Direct numerical simulation study of hydrogen/air auto-ignition in turbulent mixing layer at elevated pressures

Yao, Tong; Wen, Yang; Luo, Kai H.

doi:10.1016/j.compfluid.2018.03.075

Cited by 23 publications

(8 citation statements)

References 30 publications

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“…The scalar dissipation rate has a significant influence on turbulent autoignition. Previous studies [6,7,21] hindered, the ignition process is delayed, just like Kernel B shown in Figure 10.…”

Section: Ignition and Propagation Characteristics Of Various Ignitionmentioning

confidence: 75%

“…The extended Navier-Stokes Characteristic Boundary Conditions (NSCBC) [27,28] are used, with pressure relaxation applied along all open faces. The accuracy of the code has been assessed in several previous studies [16,18,21,[29][30][31][32][33].…”

Section: Methodsmentioning

confidence: 99%

“…The DNS domain is two-dimensional with periodic and subsonic non-reflecting boundary conditions, as in [21]. The domain size is 1cm×1cm.…”

Section: Computational Configurationmentioning

confidence: 99%

“…Physical conditions investigated in the present study are listed in Table 1. The pressure is 50 atm in this study, while pressures of 1, 5, 10 and 30 atm were considered in a previous study [21]. Turbulent intensity ′ and integral length scale are set to characterize turbulence.…”

Section: Computational Configurationmentioning

confidence: 99%

“…Turbulent time scale and turbulent Reynolds number are kept identical to those in [21] for different pressures. Turbulent time scale is 1 ms, and the turbulent Reynolds number is 148.…”

Section: Computational Configurationmentioning

confidence: 99%

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Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Yao

Wang

Luo

2019

Fuel

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Autoignition of a turbulent stratified mixing layer between nitrogen-diluted hydrogen and hot air under an elevated pressure of 50 atm is studied using direct numerical simulations (DNS) in this work. Homogeneous isotropic turbulence is superimposed on the flow field. Reduced chemical mechanisms and a detailed multicomponent diffusion model are employed. In addition to turbulent mixing ignition (TMI), homogeneous mixing ignition (HMI) and laminar mixing ignition (LMI) are also investigated for comparison. Autoignition chemistry over a wide range of pressures is studied in HMI and LMI, which shows different behaviors at elevated pressures versus low pressures. The importance of H 2 O 2 and HO 2 in TMI is highlighted as radical sinks during the ignition process and can also be used as an indicator for locating the ignition spots. Moreover, OH radicals can be used as a marker variable for the transition of autoignition to flame propagation under high pressure. According to the present study, turbulence has 2 some influence on the radical explosion stage especially for the conservation of H 2 O 2 under the elevated pressure of 50 atm. Autoignition kernels forming away from the most reactive mixture fraction isosurface are identified, which is a hybrid of autoignition and diffusive-ignition.

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Section: Ignition and Propagation Characteristics Of Various Ignitionmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

“…The DNS domain is two-dimensional with periodic and subsonic non-reflecting boundary conditions, as in [21]. The domain size is 1cm×1cm.…”

Section: Computational Configurationmentioning

confidence: 99%

Section: Computational Configurationmentioning

confidence: 99%

“…Turbulent time scale and turbulent Reynolds number are kept identical to those in [21] for different pressures. Turbulent time scale is 1 ms, and the turbulent Reynolds number is 148.…”

Section: Computational Configurationmentioning

confidence: 99%

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Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Yao

Wang

Luo

2019

Fuel

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Experimental and theoretical study of combustion efficiency of hydrogen‐oxygen mixture at pressure of 0.25 to 6.0 MPa

Aminov

Egorov

2022

Intl J of Energy Research

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The paper presents the new results of experimental and theoretical studies of combustion processes in hydrogen-oxygen mixtures. Considered the impact of pressure in the combustion chamber on the efficiency of hydrogen fuel combustion. Experimental research results showed that the hydrogen content on the exit from the first and second sections of the experimental combustion chamber was 5.674% mass and 0.719% mass, respectively, at the pressure of 1.0 MPa. The proposed pressure range extension is based on computational experiments relating mathematical modeling of the processes occurring in the experimental setup, in particular, for the pressure in the combustion chamber and flame tube ranging from 0.25 to 6.0 MPa. The obtained results were verified. The accuracy in estimating the temperature of combustion products found due to the computational and physical experiments is in the range of 98.89%-102.37% at the outlet of the first section, and is in the range of 97.38%-97.86% at the outlet of the second section. Meanwhile, the accuracy in estimating the hydrogen underburning is in the range of 100.37%-101.53% at the outlet of the first section, and is in the range of 98.81%-99.05% at the outlet from the second section. Computational experiments show that an increase in the combustion products pressure leads to an increase in the combustion products temperature at the exit from the first section was within 1264 C-1713 C range, and on the exit from the second section was within 937 C-1386 C. It is shown that the recombination rate achieved in the experimental setup and computational experiments was 10.718 to 10.814 kg/(kgÁs) at the pressure from 0.25 to 6.0 MPa. In this case, the minimum time necessary to complete recombination of combustion products was 0.5478 to 0.55 s under given conditions of external cooling. The pressure range in the combustion chamber does not significantly affect the mass fraction unreacted hydrogen.

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Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

Chi

Abdelsamie

Thévenin

2018

Flow Turbulence Combust

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A systematic study relying on Direct Numerical Simulations (DNS) of premixed hydrogen-air mixtures has been performed to investigate the hotspot ignition characteristics and ignition probability under turbulent conditions. An ignition diagram is first obtained under laminar conditions by a parametric study. The impact of turbulence intensity on ignition delays and ignition probability is then quantified in a statistically-significant manner by repeating a large number of independent DNS realizations. By tracking in a Lagrangian frame the ignition spot, the balance between heat diffusion and heat of chemical reaction is observed as function of time. The evolution of each chemical species and radicals at the ignition spot is checked and the mechanism leading to ignition or misfire are analyzed. It is observed that successful ignition is mostly connected to a sufficient build-up of a HO2 pool, ultimately initiating production of OH. Turbulence always delays ignition, and ignition probability goes to zero at sufficiently high turbulence intensity when keeping temperature and size of the initial hotspot constant.

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Direct numerical simulation study of hydrogen/air auto-ignition in turbulent mixing layer at elevated pressures

Cited by 23 publications

References 30 publications

Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Experimental and theoretical study of combustion efficiency of hydrogen‐oxygen mixture at pressure of 0.25 to 6.0 MPa

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

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Direct numerical simulation study of hydrogen/air auto-ignition in turbulent mixing layer at elevated pressures

Cited by 23 publications

References 30 publications

Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Experimental and theoretical study of combustion efficiency of hydrogen‐oxygen mixture at pressure of 0.25 to 6.0 MPa

Direct Numerical Simulations of Hotspot-induced Ignition in Homogeneous Hydrogen-air Pre-mixtures and Ignition Spot Tracking

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Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm

Formation and evolution of flame kernels in autoignition of a turbulent hydrogen/air mixing layer at 50 atm