Modeling of turbulent deflagration behaviors of premixed hydrogen-air in closed space with obstacles

Sheng, Zhonghua; Yang, Guogang; Li, Shian; Shen, Qiuwan; Sun, Hedong; Jiang, Ziheng; Liao, Jiadong; Wang, Hao

doi:10.1016/j.psep.2022.03.044

Cited by 24 publications

(5 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, the numerical results are slightly larger than those of the experiment due to the neglect of the wall heat dissipation and heat radiation in the simulation. Nevertheless, the overall simulation data are better than the results in the existing literature [15,21], especially the flame front results: the average relative error between the experiment and simulation is about 3%. Based on the above comparisons of the flame position and overpressure, the numerical model used in this study reliably captures the flame propagation and overpressure distribution during the explosion of premixed hydrogen/air in a closed duct, which further demonstrates that the numerical model and calculation method can be adopted to explore the influence of the obstacle gradient arrangement on the flame structure and explosion overpressure.…”

Section: Validation Of Simulation Resultscontrasting

confidence: 54%

“…Therefore, studying the acceleration mechanism of obstacle-induced flames is essential to prevent flame acceleration and DDT formation [15,16]. The study of combustion and explosion of channel obstacles has become an important topic, for which scholars have researched premixed gas explosions related to obstacle-related factors.…”

Section: Introductionmentioning

confidence: 99%

“…The results indicated that the flame front will not recover to a regular front after passing through many gap grid obstacles. Sheng et al [15] revealed the effects of three different shaped obstacles, namely, triangles, squares, and circles, on premixed flames. They pointed out that the peak overpressure caused by triangular obstacles was 7% and 30% higher than that of square and circular obstacles, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Wang,

Zhong

2024

Processes

View full text Add to dashboard Cite

In this paper, computational fluid dynamics (CFD) numerical simulation is employed to analyze and discuss the effect of obstacle gradient on the flame propagation characteristics of premixed hydrogen/air in a closed chamber. With a constant overall volume of obstacles, the obstacle blocking rate gradient is set at +0.125, 0, and −0.125, respectively. The study focuses on the evolution of the flame structure, propagation speed, the dynamic process of overpressure, and the coupled flame–flow field. The results demonstrate that the flame front consistently maintains a jet flame as the obstacle gradient increases, with the wrinkles on the flame front becoming increasingly pronounced. When the blocking rate gradients are +0.125, 0, and −0.125, the corresponding maximum flame propagation speeds are measured at 412 m/s, 344 m/s, and 372 m/s, respectively, indicating that the obstacle gradient indeed increases the flame propagation speed. Moreover, the distribution of pressure is closely related to changes in the flame structure, with the overpressure decreasing in the obstacle channel as the obstacle gradient increases. Furthermore, the velocity vector and vortex distribution in the flow field are revealed and compared. It is found that the obstacle tail vortex is the main factor inducing flame evolution and flow field changes in a closed chamber. The effect of the blocking rate gradient on flow velocity is also quantified, with instances of deceleration occurring when the blocking rate gradient is −0.125.

show abstract

Section: Validation Of Simulation Resultscontrasting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Wang,

Zhong

2024

Processes

View full text Add to dashboard Cite

show abstract

“…In addition, shock waves can also cause vortex phenomena in CH 4 /H 2 mixtures, which are conducive to the formation and development of turbulent flames . Turbulent flames can significantly increase the flame surface area, increase the transfer rate of heat and activation centers, and accelerate the mixing process between burned and unburned gases, which increases the combustion and propagation rates and leads to accelerated propagation of shock waves. − The positive feedback mechanism dominated by flame-driven shock waves and shock wave-induced flame acceleration leads to a gradual increase in P P along the pipeline axis in the early stage of the first evolution region. The positive feedback mechanism gradually decouples as the distance between the flame and the shock wave increases.…”

Section: Resultsmentioning

confidence: 99%

Effects of Hydrogen Blending Ratio and Equivalence Ratio on the Dynamic Characteristics of Deflagration Shock Waves of CH₄/H₂ Mixtures

Liu,

Peng

et al. 2024

ACS Omega

View full text Add to dashboard Cite

To evaluate the explosion hazard of CH4/H2 mixtures, experiments were conducted in a long and closed pipeline with a length-to-diameter ratio of 51 and built-in obstacles, and the characteristic parameters of deflagration shock waves were analyzed under different hydrogen blending ratios (0 ≤ λ ≤ 100%) and equivalence ratios (0.5 ≤ Φ ≤ 3). The results indicate that within the range of Φ = 0.8–1.2, the explosion overpressure (P P) exhibits a “two-zone” structure distribution. When 0 ≤ λ ≤ 80%, P P shows an initial increase and then a decrease in both regions, while deflagration to detonation transition (DDT) occurs in the second evolution region when λ = 100%, which is caused by the different strengths of the positive feedback mechanism coupled with flames and shock waves. The P max, (dP/dt)max, and V a show a trend of first increasing and then decreasing and monotonically increasing with the increase of the equivalence ratio and hydrogen blending ratio, respectively, and reach their maximum values at Φ = 1.0 and λ = 100%. For CH4/H2 mixtures with low hydrogen blending ratios (λ = 0 and 20%), the P max and (dP/dt)max in the fuel-lean conditions (Φ = 0.9 and 0.8) are higher than those in the fuel-rich conditions (Φ = 1.1 and 1.2), while the CH4/H2 mixtures under high hydrogen blending ratios (λ = 80 and 100%) are the opposite. Overall, the increase in H2 at a high hydrogen blending ratio and the increase in the equivalence ratio at a fuel-lean condition significantly enhance the average V a. In addition, chemical kinetics analysis found that R38 and R52 elementary reactions are the dominant elementary reactions that promote and inhibit temperature increase, respectively. Their temperature sensitivity coefficients are negatively correlated with the hydrogen blending ratio and positively correlated with the equivalence ratio. The research results provide vital information for evaluating the explosion hazards of CH4/H2 mixtures and developing safety protection measures.

show abstract

“…After experimentation, Li et al [21] suggested these obstacles could have a great influence on the explosion overpressure and the flame propagation based on the different shapes of trapezoid, circle, square and rectangle. Sheng et al [22] and Yu et al [23] found that compared with other geometric barrier plates, triangular barrier plates produced the largest overpressure and had the strongest influence on flame turbulence, which should be related to the sphericity coefficient of obstacles [24]. Xiao et al [25] proposed that obstacles with tips would promote the generation of flow instability and produce more intense flame propagation behavior.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Premixed Methane–Air Explosion in a Closed Tube with U-Type Obstacles

et al. 2022

View full text Add to dashboard Cite

Given the spatial structures and functional requirements, there are a number of different types of obstacles in long and narrow confined spaces that will cause a premixed gas explosion to produce greater overpressure and influence the flame behavior for different obstacles. Because the volume fraction of unburned gas changes with the changing height of the U-type obstacles, we can further study the influence on the volume fraction of the unburned premixed gas for the characteristics of the overpressure and the flame behaviors in the closed tube with the obstacles. The results show that after the premixed gas is successfully ignited in the pipe, the overpressure in the pipe greatly increases as the unburned premixed gas burns between the adjacent plates. Moreover, the increase of the overpressure in the closed duct becomes faster when the decrease of unburned gas becomes faster. The high-pressure areas between the plates move inversely compared with the direction of flame propagation when the height of the U-type increases, whereas the high pressure in the front of the flame moves further when the flame propagation passes all obstacles. In addition, the reversed flow structure of the flame is a coupling result for the overpressure caused by the flame propagation and the vortex between the plates. From the perspective of production safety, this study is a significant basic subject about the characteristics of overpressure and flame behaviors in a closed tube with obstacles.

show abstract

Modeling of turbulent deflagration behaviors of premixed hydrogen-air in closed space with obstacles

Cited by 24 publications

References 47 publications

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Effects of Hydrogen Blending Ratio and Equivalence Ratio on the Dynamic Characteristics of Deflagration Shock Waves of CH₄/H₂ Mixtures

Numerical Simulation of Premixed Methane–Air Explosion in a Closed Tube with U-Type Obstacles

Contact Info

Product

Resources

About

Modeling of turbulent deflagration behaviors of premixed hydrogen-air in closed space with obstacles

Cited by 24 publications

References 47 publications

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Effect of Obstacle Gradient on the Deflagration Characteristics of Hydrogen/Air Premixed Flame in a Closed Chamber

Effects of Hydrogen Blending Ratio and Equivalence Ratio on the Dynamic Characteristics of Deflagration Shock Waves of CH4/H2 Mixtures

Numerical Simulation of Premixed Methane–Air Explosion in a Closed Tube with U-Type Obstacles

Contact Info

Product

Resources

About

Effects of Hydrogen Blending Ratio and Equivalence Ratio on the Dynamic Characteristics of Deflagration Shock Waves of CH₄/H₂ Mixtures