The Measuring of Sodium Droplet Size Distribution and its Impact on the Consequence of Sodium Spray Fire

2017 ◽  
Author(s):  
Wang Guozhi ◽  
Du Haiou ◽  
Wang Rongdong ◽  
Shi Wentao ◽  
Piao Jun
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Input Data ◽  
Drop Size ◽  
Droplet Size Distribution ◽  
Drop Size Distribution ◽  
Liquid Sodium ◽  
The Real ◽  
Temperature And Pressure ◽  
The Impact

The sodium droplet size distribution has significant impact on the consequence of sodium spray fire. And it is fundamental input data for the validation and application of sodium spray fire code. The experiments were carried out in a closed vessel to measure the sodium droplet size distribution. Liquid sodium of 250 °C was sprayed downward into the vessel in the form of sodium droplets through a nozzle with a diameter of 2.4mm. The vessel was inerted by argon gas to prevent the sodium droplets from burning. A real time spray droplet sizing system based on ensemble diffraction technique was used to measure the size of the droplets. And the laser beam was passed through two glass windows on the wall of the vessel to reach the sodium droplets. The tests showed that the sizes of the sodium droplets ranged from 184μm to 1000μm at the nozzle pressure of 0.15MPa. And median diameter was 532μm. The sodium spray fire code named NACOM was used to evaluate the impact of particle size distribution on sodium fire. The measured sodium droplets size distribution and the Nukiyama-tanasama drop size distribution were divided into 11 groups to be used as input data for the NACOM code. A comparison showed that 23% of particles in Nukiyama-tanasama drop size distribution were over 1000μm, while the largest size of particles in the measured sodium droplets was 1000μm. The calculation by NACOM code showed that the trend and value of temperature and pressure in the vessel were similar, so to some extent Nukiyama-tanasama drop size distribution is a good approximation of the real sodium droplet size distribution. However, Nukiyama-tanasama drop size distribution may be unsuitable for application in sodium fire safety analysis, because the temperature and pressure calculated from which was lower than that of the real droplet size distribution.

scholarly journals Impact of hygroscopic seeding on the initiation of precipitation formation: results of a hybrid bin microphysics parcel model

2021 ◽  
Author(s):  
Istvan Geresdi ◽  
Lulin Xue ◽  
Sisi Chen ◽  
Youssef Wehbe ◽  
Roelof Bruintjes ◽  
...  
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Ostwald Ripening ◽  
Drop Size Distribution ◽  
Water Soluble ◽  
Substantial Contribution ◽  
Cloud Base ◽  
Model Framework ◽  
The Impact ◽  
Precipitation Formation

Abstract. A hybrid bin microphysical scheme is developed in a parcel model framework to study how natural aerosol particles and different types of hygroscopic seeding materials affect the precipitation formation. A novel parameter is introduced to describe the impact of different seeding particles on the evolution of the drop size distribution. The results of more than 100 numerical experiments using the hybrid bin parcel model show that: (a) The Ostwald-ripening effect has a substantial contribution to the broadening of the drop size distribution near the cloud base. The efficiency of this effect increases as the updraft velocity decreases. (b) The efficiency of hygroscopic seeding is significant only if the size of the seeding particles is in the coarse particle size range. The presence of the water-soluble background coarse particles reduces the efficiency of the seeding. (c) The efficient broadening of the size distribution due to the seeding depends on the width of the size distribution of water drops in the control cases, but the relation is not as straightforward as in the case of the glaciogenic seeding.

scholarly journals Characterization and Simulation of a Low-Pressure Rotator Spray Plate Sprinkler Used in Center Pivot Irrigation Systems

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1684 ◽  
Author(s):  
Cruz Octavio Robles Rovelo ◽  
Nery Zapata Ruiz ◽  
Javier Burguete Tolosa ◽  
Jesús Ramiro Félix Félix ◽  
Borja Latorre
Keyword(s):  
Drag Coefficient ◽  
Distribution Pattern ◽  
Size Distribution ◽  
Water Distribution ◽  
Drop Size ◽  
Low Pressure ◽  
Drop Size Distribution ◽  
Energy Losses ◽  
Conventional Model ◽  
The Impact

Spray sprinklers enable to operate at low pressures (<103 kPa) in self-propelled irrigation machines. A number of experiments were performed to characterize the water distribution pattern of an isolated rotator spray plate sprinkler operating at very low pressure under different experimental conditions. The experiments were performed under two pressures (69 kPa and 103 kPa) and in calm and windy conditions. The energy losses due to the impact of the out-going jet with the sprinkler plate were measured using an optical technique. The adequacy to reproduce the measured water distribution pattern under calm conditions of two drop size distribution models was evaluated. A ballistic model was used to simulate the water distribution pattern under wind conditions evaluating three different drag models: (1) considering solid spherical drops; (2) a conventional model based on wind velocity and direction distortion pattern, and (3) a new drag coefficient model independent of wind speed. The energy losses measured with the optical method range from 20% to 60% from higher to lower nozzle sizes, respectively, for both evaluated working pressures analyzing over 16,500 droplets. For the drop size distribution selected, Weibull accurately reproduced the water application with a maximum root mean square error (RMSE) of 19%. Up to 28% of the RMSE could be decreased using the wind-independent drag coefficient model with respect to the conventional model; the difference with respect to the spherical model was 4%.

Fluid Flow Phenomena and Droplet Size Distribution Along the Feed Spreader of Large Oil/Water Tank Separators

2009 ◽  
Author(s):  
Jose G. Severino ◽  
Luis E. Gomez ◽  
Steve J. Leibrandt ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Droplet Size Distribution ◽  
Separation Performance ◽  
Water Tank ◽  
Water Dispersion ◽  
Flow Phenomena ◽  
Oil Water ◽  
The Impact

Large gravity separation tanks play an essential role in crude oil production in many fields worldwide. These tanks are used to separate water from an oil-rich stream before safely returning it to the environment. The oil/water dispersion enters the tanks through a feed spreader consisting of an array of pipes with small effluent nozzles. A major challenge is being able to predict oil/water dispersion distribution along the spreader as well as, the maximum water droplet size exiting through the effluent nozzles, under a given set of conditions. The capacity of the studied tank is 80,000 barrels (12,719 m3). Current feed stream is about 60,000 bpd (9,540 m3/day) of wet crude containing about 20% water by volume. A significant increase in flow rates and water volume fraction is anticipated [7], as more wells are added and existing ones mature. This work is aimed at investigating the separation performance of these tanks under current and future flow conditions; focusing primarily on the flow phenomena and droplet size distribution inside the spreader. The main objective is then to identify the impact of the spreader’s geometry and piping configuration on flow behavior and tank’s separation efficiency. The final product provides key information needed for mechanistic modeling the tank separation performance and optimizing tank components’ design. The feed spreader is simulated using Computational Fluid Dynamics (CFD) to assess oil/water flow distribution inside the network. Droplet size distribution along branch-pipes effluent nozzles in, including droplet breakup and coalescence has been studied using the Gomez mechanistic model [2] with input from CFD results. An experimental investigation of the spreader using a scaled prototype was also conducted to better understand flow phenomena and verify the CFD models. Results confirm the occurrence of significant maldistribution of the water and oil phases along the spreader that could impair separation efficiency.

scholarly journals Modelling Spray Pressure Effects on Droplet Size Distribution from Agricultural Nozzles

2021 ◽  
Vol 11 (19) ◽  
pp. 9283
Author(s):  
Emanuele Cerruto ◽  
Giuseppe Manetto ◽  
Rita Papa ◽  
Domenico Longo
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Droplet Size Distribution ◽  
Drop Size Distribution ◽  
Pressure Effects ◽  
Hollow Cone ◽  
Immersion Method ◽  
Color Code ◽  
Working Pressure ◽  
Custom Made

For spray applications, drop size is the most important feature as it affects all aspects of a phytosanitary treatment: biological efficacy, environmental pollution, and operator safety. In turn, drop size distribution depends on nozzle type, liquid properties, and working pressure. In this research, three nozzles were studied under ordinary working conditions and the effect of pressure on drop size distribution was assessed. The nozzles under test, all from Albuz (France), were an orange hollow cone nozzle ATR 80 (European color code), an air induction flat spray nozzle AVI 11003, and an air induction hollow cone nozzle TVI 8002. The ATR 80 and the TVI 8002 nozzles were tested at four pressure values: 0.3, 0.5, 1.0, and 1.5 MPa; the AVI 11003 nozzle was tested at 0.3 and 0.5 MPa. The drop size measurement technique was based on the liquid immersion method by using a custom-made test bench; spray quality parameters were computed by means of suitable functions written in R language. Results showed that an increase in working pressure caused an increase in drop pulverization regardless of the type of nozzle, and drop pulverization was higher for the turbulence nozzle than for the two air induction nozzles. Based on skewness and kurtosis values, the theoretical gamma distribution was the most adapt to fit the experimental data. The scale parameter showed a decreasing trend with the increase in the pressure, a clear index of higher drop pulverization.

scholarly journals The impact of fluctuations and correlations in droplet growth by collision-coalescence revisited. Part I: Numerical calculation of post-gel droplet size distribution

2016 ◽  
Author(s):  
Lester Alfonso ◽  
Graciela B. Raga
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Sol Gel ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Stochastic Simulation Algorithm ◽  
Droplet Growth ◽  
Sol Gel Transition ◽  
The Impact ◽  
Gel Transition

Abstract. The impact of stochastic fluctuations in cloud droplet growth is a matter of broad interest, since stochastic effects are one of the possible explanations of how cloud droplets cross the size-gap and form the raindrop embryos that trigger warm rain development in cumulus clouds. Most theoretical studies in this topic rely on the use of the kinetic collection equation, or the stochastic simulation algorithm (Gillespie 1975). However, the kinetic collection equation is a deterministic equation with no stochastic fluctuations. Moreover, the traditional calculations using the kinetic collection equation are not valid when the system undergoes a transition from a continuous distribution to a distribution plus a runaway raindrop embryo (known as the sol-gel transition). On the other hand, the stochastic simulation algorithm, although intrinsically stochastic, fails to reproduce adequately the large end of the droplet size distribution due to the huge number of realizations required. Therefore, the full stochastic description of cloud droplet growth must be obtained from the solution of the master equation for stochastic coalescence. In this study the master equation is used to calculate the evolution of the droplet size distribution after the sol-gel transition. These calculations show that after the formation of the raindrop embryo, the expected droplet mass distribution strongly differs from the results obtained with the kinetic collection equation. Furthermore, the low mass bins and bins from the gel fraction are strongly anti-correlated in the vicinity of the critical time, this being one of the possible explanations for the differences between the kinetic and stochastic approaches after the sol-gel transition. Calculations performed within the stochastic framework provide insight into the inability of explicit microphysics cloud models to explain the droplet spectral broadening observed in small, warm clouds.

Drop Size Distribution Characteristics of Typhoon Haishen (2020) in Korea

2021 ◽  
Author(s):  
Jeong A Kim ◽  
Dong-In Lee
Keyword(s):  
Size Distribution ◽  
Korean Peninsula ◽  
Drop Size ◽  
Drop Size Distribution ◽  
Distribution Characteristics ◽  
Azimuthal Direction ◽  
Three Stages ◽  
Convective Cells ◽  
The Impact ◽  
Over Time

&lt;p&gt;Recently the frequency of autumn typhoons has increased on the Korean Peninsula and their damage has also increased. The Korea Meteorological Administration (KMA) established a super-strong stage to raise awareness of such a powerful typhoon, Typhoon Haishen (2020). In usual the life cycle of the typhoon is divided into three stages: developing, mature, decaying. To analyze the impact of typhoon Haishen on the Korean Peninsula, this study focused on the landfall and decaying stage. To investigate the microphysical characteristics of the typhoon over time, the drop size distribution (DSD) at the azimuthal direction of the typhoon was studied. DSD variables were obtained by using PARSIVEL (PARticle SIze and VELocity) disdrometers at eleven observation sites from Geoje (34.88&amp;#176;N, 128.57&amp;#176;E) to Ulsan (35.58&amp;#176;N, 129.33&amp;#176;E) that located along the southern coast of Korea. As typhoon Haishen landed at the vicinity of Ulsan (35.3&amp;#176;N,129.3&amp;#176;E), the observation sites were included between the centre of the typhoon and the wind impact radius. Four days before typhoon Haishen landed, typhoon Maysak (2020) landed at the vicinity of Busan (35.4&amp;#176;N,128.9&amp;#176;E) and decayed. The intensity of typhoon Maysak was weakened and the form of convective cells became unclear after landing. Typhoon Haishen was also slightly weakened after landing, however, the form of convective cells and wind impact radius were continuously maintained.&lt;/p&gt;

Effects of Varying Liquid Fuel and Air Co-Flow Rates on Spray Characterisation of an Annular Co-Flow Spray Burner

2019 ◽  
Author(s):  
R. A. Alsulami ◽  
S. Nates ◽  
W. Wang ◽  
S. H. Won ◽  
Bret Windom
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Liquid Fuel ◽  
Air Flow ◽  
Droplet Size Distribution ◽  
Droplet Breakup ◽  
Flame Stability ◽  
Flow Rates ◽  
Droplet Sizes ◽  
The Impact

Abstract Development of efficient and clean combustion systems requires the understanding of all the processes experienced by a complex liquid fuel in IC engines, such as atomization, vaporization, turbulent mixing, and combustion. Many of these processes are interconnected; the atomization process, which leads to various droplet sizes can enhance or diminish the vaporization rate of the liquid fuel and consequently impact the energy conversion process. Furthermore, the combustion/flame stability of liquid-fueled gas turbine can be influenced by the fuel and the air co-flow rates delivered in the engine. Increasing the fuel and/or air flow rates can enhance droplet breakup and the turbulence of the flow, and as a result sway the droplet size distribution of the spray. This work focuses on investigating the impact of varying the fuel and air flow rates on the spray atomization (e.g. droplet size distribution) of an Annular Co-Flow Spray Burner. This was explored by measuring droplet sizes and velocities of the spray at different radial and axial positions of n-heptane fuel under nonreacting conditions. In addition, the turbulence intensity and the liquid spray droplet distribution were quantified for different fuel and air flow rate conditions. The measurements were obtained by using a Phase Doppler Particle Analyzer/Laser Doppler Velocimeter (PDPA/LDV) at P = 1 atm and T = 298 K. Moreover, the Sauter Mean Diameters for different flow conditions are predicted, using an established correlations, and compared to PDPA/LDV measurements. The results provided a fair understanding of the influence of varying the fuel and air flow rates on the droplet sizes, velocity, and turbulent intensity. Furthermore, the results presented here will support future work that will focus on unraveling the role of phase change on flame stability.

scholarly journals The impact of fluctuations and correlations in droplet growth by collision–coalescence revisited – Part 1: Numerical calculation of post-gel droplet size distribution

2017 ◽  
Vol 17 (11) ◽  
pp. 6895-6905 ◽  
Author(s):  
Lester Alfonso ◽  
Graciela B. Raga
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Sol Gel ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Stochastic Simulation Algorithm ◽  
Droplet Growth ◽  
Sol Gel Transition ◽  
The Impact ◽  
Gel Transition

Abstract. The impact of stochastic fluctuations in cloud droplet growth is a matter of broad interest, since stochastic effects are one of the possible explanations of how cloud droplets cross the size gap and form the raindrop embryos that trigger warm rain development in cumulus clouds. Most theoretical studies on this topic rely on the use of the kinetic collection equation, or the Gillespie stochastic simulation algorithm. However, the kinetic collection equation is a deterministic equation with no stochastic fluctuations. Moreover, the traditional calculations using the kinetic collection equation are not valid when the system undergoes a transition from a continuous distribution to a distribution plus a runaway raindrop embryo (known as the sol–gel transition). On the other hand, the stochastic simulation algorithm, although intrinsically stochastic, fails to adequately reproduce the large end of the droplet size distribution due to the huge number of realizations required. Therefore, the full stochastic description of cloud droplet growth must be obtained from the solution of the master equation for stochastic coalescence. In this study the master equation is used to calculate the evolution of the droplet size distribution after the sol–gel transition. These calculations show that after the formation of the raindrop embryo, the expected droplet mass distribution strongly differs from the results obtained with the kinetic collection equation. Furthermore, the low-mass bins and bins from the gel fraction are strongly anticorrelated in the vicinity of the critical time, this being one of the possible explanations for the differences between the kinetic and stochastic approaches after the sol–gel transition. Calculations performed within the stochastic framework provide insight into the inability of explicit microphysics cloud models to explain the droplet spectral broadening observed in small, warm clouds.

scholarly journals Impact of hygroscopic seeding on the initiation of precipitation formation: results of a hybrid bin microphysics parcel model

2021 ◽  
Vol 21 (21) ◽  
pp. 16143-16159
Author(s):  
Istvan Geresdi ◽  
Lulin Xue ◽  
Sisi Chen ◽  
Youssef Wehbe ◽  
Roelof Bruintjes ◽  
...  
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Ostwald Ripening ◽  
Drop Size Distribution ◽  
Water Soluble ◽  
Substantial Contribution ◽  
Cloud Base ◽  
Model Framework ◽  
The Impact ◽  
Precipitation Formation

Abstract. A hybrid bin microphysical scheme is developed in a parcel model framework to study how natural aerosol particles and different types of hygroscopic seeding materials affect the precipitation formation. A novel parameter is introduced to describe the impact of different seeding particles on the evolution of the drop size distribution. The results of more than 100 numerical experiments using the hybrid bin parcel model show that (a) the Ostwald-ripening effect has a substantial contribution to the broadening of the drop size distribution near the cloud base. The efficiency of this effect increases as the updraft velocity decreases. (b) The efficiency of hygroscopic seeding is significant only if the size of the seeding particles is in the coarse particle size range. The presence of the water-soluble background coarse particles reduces the efficiency of the seeding, (c) The efficient broadening of the size distribution due to the seeding depends on the width of the size distribution of water drops in the control cases, but the relation is not as straightforward as in the case of the glaciogenic seeding.

Sign in / Sign up

Export Citation Format

Share Document