Fire | Special Issue : Combustion Diagnostics

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20 pages, 15937 KiB

Open AccessArticle

Analysis of Flow Field Characteristics of the Propane Jet Combustion Flame

by Shengnan Li, Jingjing Guo, Zheng Chi, Bo Zhao and Shuai Zhao

Fire 2023, 6(12), 464; https://doi.org/10.3390/fire6120464 - 07 Dec 2023

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In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry [...] Read more.

In order to effectively prevent fire accidents and improve fire management capability, this paper describes the independent designs and builds of an experimental low-cost particle image velocimetry platform for a propane jet combustion flame using traditional mutual correlation theory. The particle image velocimetry (PIV) algorithm is written based on MATLAB software, allowing it to realise image preprocessing, multi-level grid window deformation inter-correlation calculations, and other functions. Fluid flow velocity and vorticity are used as entry points to study the flame combustion mechanism. The air flow field and vorticity above the propane jet flame are analysed. The results show that, from the level of fluid flow velocity, the maximum fluid flow velocity in the test area does not exceed 0.23 m/s, and the maximum transverse fluid flow velocity is close to 0.15 m/s. Additionally, the longitudinal fluid flow velocity is opposite the upper and lower portions of the longitudinal flow velocity, and there is a swirling phenomenon in the propane flame jet. From the vorticity level, the closer to the centre of the jet in the vortex plane, the faster the air flow speed, and simultaneously, in the upper and lower parts of the vortex, the air flow travels in the opposite direction and is of equal size. The particle image velocimetry platform that was independently designed in this study can efficiently characterise the dynamic flow field and the flow characteristics of complex combustion chambers, simultaneously ensuring high efficiency and reducing research costs. It provides a measurement method and experimental basis for the development of fire extinguishing equipment and numerical simulation, while also helping us to carry out a series of subsequent studies on fire extinguishing mechanisms. Full article

(This article belongs to the Special Issue Combustion Diagnostics)

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12 pages, 3233 KiB

Open AccessArticle

New Insight into the Effects of Gaseous CO₂ on Spherically Symmetric Droplet Flames

by Ter-Ki Hong and Seul-Hyun Park

Fire 2023, 6(12), 461; https://doi.org/10.3390/fire6120461 - 04 Dec 2023

Viewed by 1253

Abstract

This study investigated the effect of CO₂ on the burning behavior and radiative properties of a single ethanol droplet flame in microgravity. Measurements of the droplet burning rate, the flame size and temperature, and the radiative emissions were performed, under microgravity conditions [...] Read more.

This study investigated the effect of CO₂ on the burning behavior and radiative properties of a single ethanol droplet flame in microgravity. Measurements of the droplet burning rate, the flame size and temperature, and the radiative emissions were performed, under microgravity conditions for ethanol droplets burning in N₂ and CO₂ environments, using the 1.5 s drop tower facilities at the Korea Maritime and Ocean University (KMOU). The non-monotonic sooting behaviors (caused by the elevated O₂ concentrations) were found to have a significant influence on radiative heat losses in N₂ environments, resulting in non-linear droplet burning behaviors with O₂ concentrations. Due to the unique nature of CO₂ in microgravity, which absorbs radiative energy from the flame and raises the temperatures of the surrounding gases, the CO₂ environments suppressed the radiative heat losses from the flame, regardless of the non-monotonic sooting behavior observed at the higher O₂ concentrations. These experimental findings highlight the complicated physics of CO₂ gas radiation in microgravity, which has not been quantitatively explored. Full article

(This article belongs to the Special Issue Combustion Diagnostics)

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17 pages, 3838 KiB

Open AccessArticle

Fire Ignition and Propagation in Hidden Zones of Aircrafts: A Novel Confined Fire Apparatus (CFA) for Flame Spreading Investigation

by Vasiliki N. Papadogianni, Alexandros Romeos, Athanasios Giannadakis, Konstantinos Perrakis and Thrassos Panidis

Fire 2023, 6(8), 292; https://doi.org/10.3390/fire6080292 - 31 Jul 2023

Viewed by 954

Abstract

This research investigated potential fire hazards originating in hidden areas of pressurized sections of aircrafts. The objective was to establish a laboratory-scale flammability test method to predict the behavior of fire propagation under real fire conditions. A confined fire apparatus (CFA) was designed [...] Read more.

This research investigated potential fire hazards originating in hidden areas of pressurized sections of aircrafts. The objective was to establish a laboratory-scale flammability test method to predict the behavior of fire propagation under real fire conditions. A confined fire apparatus (CFA) was designed and constructed, and several tests were conducted to better understand the involved mechanisms and their consequences and to estimate flame spreading in hidden-zone fires. The experimental facility and flame-spreading results obtained for a typical material involved in hidden fires, specifically a ceiling panel, were presented and discussed. The experimental facility consisted of a narrow passage where a fire was initiated using a burner on a specimen exposed to a controlled heat flux. Experiments were conducted in the absence of forced airflow. Flame spreading was estimated through visual monitoring of fire development or temperature measurements at specific locations in the specimen. Both methods yielded similar results. The flame spread velocity in relation to the imposed heat flux allowed for the estimation of the critical heat flux for spreading

{\dot{q}}_{s p, c r}^{″}

and for ignition

{\dot{q}}_{i g, c r}^{″}

; the corresponding temperatures, T_s_,min and T_ig; and the flame spread parameter Φ. Full article

(This article belongs to the Special Issue Combustion Diagnostics)

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