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ObjectiveThis study focuses on the quasi-static pressure characteristics of a confined cabin in a water mist environment. MethodsFirst, on the basis of the theoretical model of quasi-static pressure in a confined cabin in adiabatic ideal gas, two new assumptions are added to establish a theoretical model of quasi-static pressure in a confined cabin in a water mist environment. Internal explosion experiments in a confined cabin with and without water mist are then performed with the charge as an independent variable, and the quasi-static pressure is measured and used to verify the mitigation effect of water mist on quasi-static pressure and obtain its empirical formula.Results Combined with the theoretical model and experimental data analysis, it is concluded that the ability of water mist to reduce quasi-static pressure increases with the increase in charge-volume ratio, but the increase rate gradually decreases. Both the theoretical formulas of the afterburning correction term and empirical formulas can be used to estimate the quasi-static pressure peak in the cabin.ConclusionsThe experimental results verify the mitigation effect of water mist on quasi-static pressure. The experimental data of this paper and others shows good agreement with the empirical formula of the quasi-static pressure peak of an internal explosion in a water mist environment, and can be used to estimate the quasi-static pressure peak.

For exploring the influence mechanism of fine water mist system parameters on extinguishing mine belt fires, FDS was used to study the cooling characteristics and the fire extinguishing effect of fine water mist under different parameters. From the perspective of particle diameter, spray flow and nozzle spacing, the temperature change and fire extinguishing time in the roadway under fine water mist are compared and analyzed. The results show that the fire extinguishing effect is significantly affected by the system parameters. In a certain range, the fire extinguishing time decreases with the droplet particle size and decreases with the spray flow. Under the same droplet particle size and spray flow rate, the fire extinguishing time becomes larger with the increase of the nozzle spacing. Fine water mist with particle size of 100 m, nozzle flow of 8 L/min, and nozzle spacing of 1 m can quickly reduce the temperature of the fire field and effectively inhibit the spread of fire.

Copyright of Fire Safety Science is the property of Fire Safety Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At present, the application of water mist fire extinguishing system in the field of ships has attracted extensive attention, but there are few studies on the fire extinguishing performance of water mist in specific compartments. In order to explore the fire extinguishing effect of water mist on ship fires, the fire extinguishing effect of water mist on two typical ship compartments(large-space storage compartment and small-space living compartment)was simulated using FDS software. The effects of particle size, atomization angle and flow coefficient on fire extinguishing and cooling performance were analyzed. The simulation results show that the fire extinguishing performance of water mist in the large space storage cabin is poor, and the fire extinguishing and cooling can not be carried out. The water mist fire extinguishing and cooling performance in the small living room is relatively good. It is revealed that the fire extinguishing performance of water mist in the living room increases with the decrease of particle size, the decrease of atomization angle and the increase of flow coefficient. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to study the effectiveness of smoke retaining vertical wall combined with water mist as smoke prevention separation in the pipe gallery, the coupling effect of smoke retaining vertical wall and water mist in the pipe gallery was studied through the numerical simulation software FDS. The results show that when the water mist flow rate is 0. 5 L/ min, four kinds of fine water mist with average particle size of 50, 100, 200 and 300 μm are compared, water mist of 50 μm has the most obvious effect on the reduction of flue gas temperature. This is because the vertical velocity of flue gas is reduced by the smoke baffle wall, and the water mist can overcome the longitudinal inertia force without large particle size. Therefore, the appropriate particle size range of the smoke baffle water mist coupled with the smoke baffle wall should be between 50 μm and 100 μm. When the flow rate is 0. 5 ~3. 0 L/ min, the reduction rate of heat flux downstream of the nozzle under the action of the water mist curtain is 46. 6%, 60. 7%, 82. 9%, 85. 7%, 87. 0% and 87. 3%, respectively. The greater the flow rate of the nozzle, the less the heat passing through the cross section of the pipe gallery downstream of the nozzle, but the continuous increase of the flow rate, the heat flux reduction is no longer obvious, it can be seen that there is an optimal flow rate. The water mist and the smoke retaining vertical wall have a synergistic effect, and the combined effect has a good effect on blocking the spread of smoke in the pipe gallery. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to analyze the mitigating effect of water mist on the explosive shock wave inside a cabin, a series of TNT explosion experiments in the center of a cabin were carried out, from which the wall pressure and quasi-static pressure inside the cabin in different cases with and without water mist were measured. Results show that water mist truly has an evident effect on attenuating the overpressure peak of blast wave and the quasi-static pressure. In the experiment of 27.5g TNT exploding in cabin, the attenuation rate of initial shock wave overpressure is 26.47%, the attenuation rate of secondary reflected wave pressure is is about 27.27%, and the attenuation rate of quasi-static pressure is about 31.82%. For the same water mist density, the mitigating effect of water mist on the blast wave decreases with the increase in TNT charge. [ABSTRACT FROM AUTHOR]

This study assembles a pipeline mist spraying experiment rig and measures the motion characteristics of water mist in the square pipeline using Particle Image Velocimeter. It explores the settling law of water mist in the pipeline with various spraying pressure and airflow velocity and analyzes their influences. The results indicate that the settling volume increases by 96% in the 1 meter long downstream pipeline, when the spraying pressure increases from 0. 1 MPa to 1. 3 MPa at a set airflow velocity, which is mainly caused by impinging. And the settling volume reduces by 76% in the other parts of the pipeline, which is caused by inertance. But when airflow velocity increases from 1.1 m/s to 10.4 m/s with a set spraying pressure, the settling volume reduces by 24% in the 1 meter long pipeline and reduces by 17% in the other parts. The results will provide a reliable theoretical basis for gas explosion suppression and the parameter setting of water mist in the safe transportation of low concentration gas. [ABSTRACT FROM AUTHOR]

Water mist for fire suppression and control has received considerable attention as one of the potential measures for replacing HALON. Information on volume mean diameter and coordinate component velocity of two types of water mist has been obtained by using LDA/APV system and the mechanism of fire suppression using water mist been explored with the aid of Cup Burner system. A series of experimental study has been conducted to observe the effectiveness of CH4/air fire suppression using water mist. The results show that water mist consisting of 10 ~ 100 jMin diameter droplets is an effective flame suppressant in a co-flow cup burner flame. The diameter and mass fraction of water mist significantly affect the temperature distribution of the methane CH4/air flame. The effect of oxygen dilution is more prominent in the upper part of the flame, whereas, endothermic heat exchange with the droplets plays a critical role in the lower half of the diffusion flame. [ABSTRACT FROM AUTHOR]

Water mist for fire control and suppression has received considerable attention as one of potential methods for replacing halon. The effectiveness of water mist fire suppression systems (WMFSS) can also be further enhanced by additives. A series of experiments has been conducted to explore the CH4/air fire suppression effectiveness by using water mist with metal chloride additives. The results show that the metal chloride can obviously improve fire suppression efficacy of water mist, which can be affected by the type and concentration of metal chloride. Six types of metal chloride as the additives were used in experiments. It is found that, with the same mass fraction, their fire suppression effectiveness is gradually enhanced in order of MgCl2, CaCl2, NaCl, KCl, MnCl2 and FeCl2. Because of three co-existing effects, there must be an optimal fire suppression effectiveness, which corresponds to the concentration matching of metal chloride with water mist. [ABSTRACT FROM AUTHOR]