Turbulent premixed flame characteristics of a CO/H2/O2 mixture highly diluted with CO2 in a high-pressure environment

Kobayashi, Haruo; Otawara, Yuki; Wang, Jinhua; Matsuno, Futoshi; Ogami, Yasuhiro; Okuyama, Masaki; Kudo, Taku; Kadowaki, Shigenori

doi:10.1016/j.proci.2012.05.048

Cited by 50 publications

(25 citation statements)

References 15 publications

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“…Hayakawa et al [18] investigated the turbulent burning velocity at fixed turbulence Karlovitz numbers and showed that the ratio of turbulent burning velocity to unstretched laminar burning velocity increases with a decrease in Markstein number. Kobayashi et al [22] proposed that the Markstein length affects the flame surface density of the turbulent flame front via a change in the passivity of the flame front. Bradley et al [23] expressed the correlation between turbulent burning velocity and effective turbulence intensity.…”

Section: Introductionmentioning

confidence: 99%

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Hayakawa

Goto

Mimoto

et al. 2015

Fuel

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519

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h i g h l i g h t sLaminar burning velocities of ammonia/air flames at high pressures are evaluated. Maximum value of laminar burning velocity of ammonia/air flame is about 7 cm/s. Laminar burning velocity decreases with the increase in the pressure. Markstein length increases with the increase in equivalence ratio. Markstein lengths at high pressure are lower than those at 0.1 MPa. a b s t r a c tAmmonia is expected to be useful not only as a hydrogen-energy carrier but also as a carbon-free fuel. In order to design an ammonia fueled combustor, fundamental flame characteristics of ammonia must be understood. However, knowledge of the characteristics of ammonia/air flames, especially at the high pressures, has been insufficient. In this study, the unstretched laminar burning velocity and the Markstein length of ammonia/air premixed flames at various pressures up to 0.5 MPa were experimentally clarified for the first time. Spherically propagating premixed flames, which propagate in a constant volume combustion chamber, were observed using high-speed schlieren photography. Results indicate that the maximum value of unstretched laminar burning velocities is less than 7 cm/s within the examined conditions and is lower than those of hydrocarbon flames. The unstretched laminar burning velocity decreases with the increase in the initial mixture pressure, tendency being the same as that of hydrocarbon flames. The burned gas Markstein length increases with the increase in the equivalence ratio, the tendency being the same as that of hydrogen/air flames and methane/air flames. The burned gas Markstein lengths at 0.1 MPa are higher than those at 0.3 MPa and 0.5 MPa. However, the values of burned gas Markstein length at 0.3 MPa and 0.5 MPa are almost the same. In addition, numerical simulations using CHEMKIN-PRO with five detailed reaction mechanisms which are presently applicable for the ammonia/air combustion were also conducted. However, qualitative predictions of unstretched laminar burning velocity using those reaction mechanisms are inaccurate. Thus, further improvements of reaction mechanisms are essential for application of ammonia/air premixed flames.

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Section: Introductionmentioning

confidence: 99%

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Hayakawa

Goto

Mimoto

et al. 2015

Fuel

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519

210

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“…Converting methane into power source of small-scale practical applications without nitrogenoxides emissions, we shall obtain the knowledge on micro methaneoxygen flames. Oxy-fuel combustion has been investigated in detail to clarify the fundamental phenomena [1][2][3][4]. In addition, small-scale combustion has been treated to elucidate the characteristics of micro flames [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Micro Methane-Oxygen Counterflow Diffusion Flames: Effects of Gravity on Flame Structures

Kadowaki

Hashimoto

Katsumi

et al. 2018

J. Phys.: Conf. Ser.

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We manipulated oxy-fuel combustion of methane in small scales to study the characteristics of micro counterflow diffusion flames under the gravity field. Methane-oxygen diffusion flames in counterflow burners were observed, where the burner distance was less than or equal to 1.0 mm and the apparent equivalence ratio was unity. The flame thickness and flame diameter were obtained as functions of the burner distance and gas flow rate. The minimum burner distance for the observation of flames became smaller as the gas flow rate increased. We obtained smaller values of the minimum burner distance when methane flowed out from the upper burner. The flame thickness and flame diameter decreased as the burner distance became smaller. In addition, the flame thickness and flame diameter had slightly larger values in the upper-methane case.

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“…Several researchers have studied oxygen combustion and clarified its fundamental phenomena (Maruta et al, 2007;Toftegaard et al, 2010;Sevault et al, 2012;Kobayashi et al, 2013;Bongartz and Ghoniem, 2015;Shimokuri et al, 2015). Research works on micro flames have revealed the essence of small-scale combustion (Miesse et al, 2005;Chen et al, 2007;Ju and Maruta, 2011;Hirasawa et al, 2013;Saiki and Suzuki, 2013;Nakamura et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Oxygen combustion of CH<sub>4</sub>-CO<sub>2</sub> mixture in a small-scale counterflow burner

Kadowaki

Kohatsu²,

Uehara³

et al. 2018

JTST

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Oxygen combustion of CH4-CO2 mixture in a small-scale counterflow burner was studied. A diffusion flame was stabilized in the gap between opposed ports ejecting fuel and oxygen gases, and its thickness which depended on the gap distance between burner ports, inner diameter of burner tubes, flow rate of gases and fuel gas component was measured. The gas flow rates were varied such that the apparent equivalence ratio became constant at unity, while the gap distance was varied in the range from 1 mm to less. It was shown that the flame thickness decreased monotonically as the gap distance decreased and that the diffusion flame became thinner when the methane concentration in fuel gas became lower. Increased flame thickness was observed at large gas flow rate, and a diffusion flame was found in smaller gap distance at larger inner diameter. From these data, the relation between the flame thickness and the flame stretch rate was summarized, showing that the flame thickness decreased as the flame stretch became stronger, i.e. the thickness varied inversely with the square root of stretch rate. To elucidate the dependence of the flame thickness on the flame stretch rate, the flame thickness normalized by the average velocity of oxygen gas and the inner diameter was introduced. It was confirmed that the normalized flame thickness depended only on the flame stretch rate.

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Turbulent premixed flame characteristics of a CO/H2/O2 mixture highly diluted with CO2 in a high-pressure environment

Cited by 50 publications

References 15 publications

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Laminar burning velocity and Markstein length of ammonia/air premixed flames at various pressures

Micro Methane-Oxygen Counterflow Diffusion Flames: Effects of Gravity on Flame Structures

Oxygen combustion of CH<sub>4</sub>-CO<sub>2</sub> mixture in a small-scale counterflow burner

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