Flame Propagation Dynamics in Open Tubes: Factors Influencing Combustion Conditions and Practical Implementations
Authors: Almyali Hussein M. , H. Al Dulaimi Zaid M. , Al-Fahham Mohammed A. 
Published: May 2024

This study examines the combustion conditions of fuel flame propagation within a tube of uniform cross-sectional area, where ignition occurs at the sealed end and the flame propagates in the direction of both the open and sealed ends. Both factors exert an influence on the configuration and functioning of combustion systems. To gain a comprehensive understanding of the impact of practical implementations in various combustion systems, it is imperative to comprehend the variations in flame propagation stages as a result of thermodynamic conditions. The operational conditions involving pressures and temperatures are considerably elevated compared to the natural settings. Numerous studies have been conducted on the propagation of flames within tubes. The present review centers on an extensive examination of the methodologies and procedures employed to investigate the phases of flame propagation, along with the impact of operational parameters on other fuels. Various aspects of flame behavior are explored in this article, focusing on flame formation, propagation, and the factors that influence them. The flame speed, which represents the rate of flame propagation, is influenced by factors such as fuel and oxidizer composition, temperature, pressure, and environmental conditions. The paper discusses the distinction between premixed and non-premixed flames and their respective characteristics. Several studies are cited to demonstrate the impact of oxygen concentration, air swirl, and fuel blending ratios on flame properties. These investigations involve experiments with different fuel-air mixtures, examining parameters such as flame luminance, temperature, soot production, and flame distortion. The measurement of laminar flame speed, which provides insights into fuel-air mixtures' diffusivity, reactivity, and exothermicity, is discussed. Various techniques for measuring laminar flame speed are mentioned, including the study of flame stability and spherical flame propagation. The paper also addresses the influence of flame stretch, which refers to the elongation or compression of a flame due to fluid flow or turbulence. Researchers aim to eliminate the effect of flame stretch to achieve accurate observations. Furthermore, the manuscript delves into factors affecting flame propagation, including the influence of aspect ratio on flame dynamics and flame oscillations. It describes experiments conducted in different geometries to observe changes in flame morphology and propagation velocity. The impact of ignition disturbances and equivalent ratio stratification on flame behavior is also explored. Studies examine the effects of ignition disruption and ignition volume on flame spread dynamics. Additionally, investigations analyze the behavior of flames under disturbances in the equivalence ratio, discussing changes in flame speed, heat release, and flame structure. Overall, these studies contribute to our understanding of flame behavior, combustion processes, and their applications in various fields, including energy production, environmental science, and engineering