A numerical investigation in buoyancy effects on micro jet diffusion flame

Liu, Lei; Zhao, Ming; Chen, Yi‐Kun; Fan, Aiwu; Li, Dan

doi:10.1007/s11771-020-4337-7

Cited by 5 publications

(2 citation statements)

References 27 publications

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“…The review concluded that the numerical simulations are capable of predicting the micro diffusion flame behavior both quantitatively and qualitatively. The effect of buoyancy on microjet hydrogen diffusion flame was studied numerically by Lei et al [30]. The results revealed that the combustion is intensified for a velocity greater than 0.2 m/s because of the radial flow due to the buoyancy effect.…”

Section: Introductionmentioning

confidence: 99%

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

et al. 2021

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Characteristics of microjet hydrogen diffusion flames stabilized near extinction are investigated numerically. Two-dimensional simulations are carried out using a detailed reaction mechanism. The effect of burner wall material, thickness, and thermal radiation on flame characteristics such as flame height and maximum flame temperature are studied. Results show that the flame stabilizes at lower fuel jet velocities for quartz burner than steel or aluminum. Higher flame temperatures are observed for low conductive burners, whereas the flame length increases with an increase in thermal conductivity of the burner. Even though thermal radiation has a minor effect on flame characteristics like flame temperature and flame height, it significantly influences the flame structure for low conductive burner materials. The burner tip and its vicinity are substantially heated for low conductive burners. The effect of burner wall thickness on flame height is significant, whereas it has a more negligible effect on maximum flame temperature. Variation in wall thickness also affects the distribution of H and HO2 radicals in the flame region. Although the variation in wall thickness has the least effect on the overall flame shape and temperature distribution, the structure near the burner port differs.

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Section: Introductionmentioning

confidence: 99%

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

et al. 2021

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“…Zhang et al [41] revealed that laminar diffusion jet flames were notably affected by the accompanying air stream under microgravity. Liu et al [42] conducted a numerical study on the effect of gravity on the free microjet flames of hydrogen. They reported that the combustion was intensified by radial air flow due to the buoyancy effect if the fuel jet velocity was above 0.2 m/s.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the Combustion Completeness of Hydrogen Jet Flames within a Mesoscale Tube under Zero Gravity

Jiang¹,

Zhao

Liu³

et al. 2021

Energies

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Microjet hydrogen flames can be directly used as micro heat sources or can be applied in micro propulsion systems. In our previous study, under zero gravity and without an active air supply, the combustion completeness of hydrogen jet flames within a mesoscale tube with an inner diameter of 5 mm was very low. In this study, we were dedicated to improving the combustion efficiency by using a convergent nozzle (tilt angle was around 68°) instead of the previous straight one, and the exit diameter was 0.8 or 0.4 mm. The numerical results demonstrate that the maximum combustion efficiency in the case of d= 0.8 mm was only around 15%; however, the peak value for the case of d = 0.4 mm was around 36%. This happened because with d = 0.4 mm, the fuel jet velocity was around four times that of the d = 0.8 mm case. Hence, the negative pressure in the combustor of d = 0.4 mm decreased to a much lower level compared to that of d = 0.8 mm, which led to an enhancement of the air entrainment ratio. However, the highest combustion efficiency of d = 0.4 mm was still below 36%; therefore, a slightly larger tube or an even smaller nozzle exit diameter will be necessary for further improvements to the combustion efficiency.

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Comparison of combustion efficiency of micro hydrogen jet flames confined in cylindrical tubes of different diameters

Zhao

Liu²,

Fan

2020

Chemical Engineering and Processing - Process Intensification

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A numerical investigation in buoyancy effects on micro jet diffusion flame

Cited by 5 publications

References 27 publications

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

Effect of Burner Wall Material on Microjet Hydrogen Diffusion Flames near Extinction: A Numerical Study

Improvement of the Combustion Completeness of Hydrogen Jet Flames within a Mesoscale Tube under Zero Gravity

Comparison of combustion efficiency of micro hydrogen jet flames confined in cylindrical tubes of different diameters

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