Numerical analysis of a water mist spray: The importance of various numerical and physical parameters, including the drag force

Liu, Yuanjun; Beji, Tarek; Thielens, Martin; Tao, Zhi; Fang, Zheng; Merci, Bart

doi:10.1016/j.firesaf.2021.103515

Cited by 8 publications

(16 citation statements)

References 15 publications

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“…Since water splashes into the enclosed space outside the barrel and on the glass, an error of 5-8% can be allowed [19]. As seen in Figure 5c,d, hot water is more effective than cold water in the oil pan.…”

Section: Water Flux Density Distributionmentioning

confidence: 98%

Influence of Water Mist Temperature Approach on Fire Extinguishing Effect of Different Pool Fires

et al. 2022

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The aim of this paper was to study the suppression influence of water mist on oil pool fires, taking diesel fires and n-heptane fires as experimental objects. The effects of spray pressure and temperature on water mist suppression were examined, and an experimental platform for the suppression of water mist in a small space was set up. Their fire prevention performance and fire extinguishing mechanisms were analyzed by comparing the flame temperature and extinguishing time of diesel and n-heptane pool fire. Three types of spray pressure were set. Water mist was designed at different temperatures and design experiments were carried out for this purpose. The change process of smoke concentration, thermocouple temperature, and flame combustion under different working conditions were analyzed, and the factors affecting the fire extinguishing effect of water mist on oil pool fire were discussed. The results show that 20 °C water mist is more effective at medium and high pressure than at low pressure. Moreover, 80 °C water mist at 9 MPa is more effective in extinguishing n-heptane fire. The flame extinction time is about 10 s, which is more than 40 s higher than that of cold water.

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Section: Water Flux Density Distributionmentioning

confidence: 98%

Influence of Water Mist Temperature Approach on Fire Extinguishing Effect of Different Pool Fires

et al. 2022

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“…The main findings indicate a strong sensitivity of fire suppression to initial droplet size, where injection of large droplets may cause an increase in overall temperature. Myers and Marshall (2016) and Liu et al (2022) developed an Euler-Lagrangian representation of sprinkler spray using CFD with the results of Ren et al (2011) and Zhou et al (2012). Further, Liu et al (2022) modeled hot air jets using FDS.…”

Section: Introductionmentioning

confidence: 99%

“…Myers and Marshall (2016) and Liu et al (2022) developed an Euler-Lagrangian representation of sprinkler spray using CFD with the results of Ren et al (2011) and Zhou et al (2012). Further, Liu et al (2022) modeled hot air jets using FDS. Sheppard (2002) conducted full-scale experiments on characterizing the suppression parameters of spray like water droplet size, droplet velocity, and water flux using Particle Image Velocimetry (PIV) and Phase Doppler Anemometry (PDA) which is also known as Phase Doppler Particle Analyzer (PDPA).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Complex Spray Behaviors of Sprinkler Spray Using FDS

Ramachandran¹,

Lundberg²

2022

Linköping Electronic Conference Proceedings

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It takes money, time, and energy to set up an experimental grid to measure the effectiveness of fire suppression parameters. Therefore, computational fluid dynamics (CFD) is an alternative in all fields as consequences modeling. Fire Dynamic Simulator (FDS) is a CFD software developed by the National Institute of Standards in Technology (NIST) to model and generate the results for the spray models. FDS uses Large Eddy Simulation (LES) to represent turbulence. The current study utilizes FDS to investigate the extinguishing efficiency of sprinkler spray on e general fire. The study focuses on analyzing the effectiveness of suppression parameters using complex (polydisperse) in contrast to the simplified (monodisperse) representation of the spray with- and without a fire scenario of a 2560 kW propane fire. Measurements were taken by digitally enabled Phase Doppler Particle Analyzer (PDPA) to measure the fire suppression parameters such as number concentration, droplet size distribution (DSD) & velocity distribution. The measurements were taken 1.5 m downstream of the sprinkler. The suppression parameters are compared with monodisperse and polydisperse with and without fire. Thus, the suppression parameters have been compared to measure the effect.

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“…The present study is motivated by an apparent lack of in-depth assessment of the drag reduction model in CFD simulations of full water sprays typical for fire suppression applications, to the best of the authors' knowledge. To that purpose, multiple water sprays, with variable level of density (or particle volume fraction, 𝛼) are investigated: the 'Wuhan' spray [16], the 'VTT' spray [17] as described in the FDS validation guide [18] and the 'Fukui' spray [19]. Based on the operating conditions and the spray characteristics, the Wuhan spray is expected to be much denser than the two other sprays and has been the starting point of this research.…”

Section: Introductionmentioning

confidence: 99%

“…The initial case for the discussion of the impact of this novel DVF-based drag reduction model on CFD simulations is the Wuhan spray, for which experiments have been carried out in order to characterize the overall shape of a water mist spray and the subsequent water density distribution on the floor [16]. The follow-up comprehensive numerical study carried on in the latter paper has shown that the predicted spray is significantly narrower (by 78%) than the actual spray.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Analysis of the Impact of a Novel Droplet Volume Fraction-Based Drag Reduction Correlation in a Numerical Study on Water Sprays with Different Levels of Density

et al. 2022

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Multiple sets of CFD simulations of water sprays have been carried out with FDS 6.7.6 with a novel expression for the drag reduction model (representing the influence of the surrounding droplets on the drag when compared to the situation for isolated droplets). The sprays are representative for use in fire suppression, but have been characterized in the absence of a fire-driven flow, which is key for a step-wise approach. Previous simulations have shown the importance of the drag reduction model, indicating that for a dense spray, a much stronger significant drag reduction seemed necessary than what is commonly applied, in order to reproduce the measured width of the spray envelope and the subsequent water flux distribution at floor level in the CFD simulations. In the present study, the drag reduction is calculated locally, depending solely on the local droplet volume fraction. It is thus only invoked in the dense region of the spray, typically near the injection. The results reveal very good agreement of the water flux distribution on the ground for the dense spray, with deviations from the experimental results that are less than 4% in the center of spray for the initial mesh. However, the simulation results are sensitive to the mesh size. The novel expression for the drag reduction model has also been tested against two other sprays to evaluate its impact in less dense sprays. The initial set of parameters leads to acceptable simulation results for less dense sprays.

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Numerical analysis of a water mist spray: The importance of various numerical and physical parameters, including the drag force

Cited by 8 publications

References 15 publications

Influence of Water Mist Temperature Approach on Fire Extinguishing Effect of Different Pool Fires

Influence of Water Mist Temperature Approach on Fire Extinguishing Effect of Different Pool Fires

Evaluation of Complex Spray Behaviors of Sprinkler Spray Using FDS

Comprehensive Analysis of the Impact of a Novel Droplet Volume Fraction-Based Drag Reduction Correlation in a Numerical Study on Water Sprays with Different Levels of Density

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