Spray Droplets Research Articles

LES of autoignition process in a turbulent droplet-laden mixing layer – impact of an evaporation model and discretisation method

This paper focuses on the numerical modelling of the autoignition process in an ethanol-air mixture within a turbulent droplet-laden temporally evolving mixing layer, utilising the Large Eddy Simulation (LES) method. We compare results obtained by implementing two notably distinct discretisation methods (second-order Total Variation Diminishing – TVD, and fifth-order Weighted Essentially Non-Oscillatory – WENO) in the species and energy transport equations. Additionally, we examine three widely recognised evaporation models (the ‘ D 2 ’ model, the Abramzon–Sirignano model, and a non-equilibrium model based on the Langmuir-Knudsen law). For modelling the combustion process, we employ the Eulerian Stochastic Field method and a laminar chemistry model. The simulations encompass two droplet diameter distributions, one with low and the other with significant diameter non-uniformity. Furthermore, nine distinct initial conditions are considered. Our findings indicate that adjusting the discretisation scheme or the evaporation model can yield simulation outcomes differing to a substantial degree, similar to the impact of modifying the actual properties of the spray droplets or their initial distribution. This is particularly pronounced in the case of sprays featuring a narrowed droplet diameter distribution. We found that the Abramzon–Sirignano model results in the most rapid autoignition. The TVD scheme contributes to a more even spatial distribution of the evaporated fuel, consequently facilitating quicker evaporation and faster autoignition. Using the WENO scheme generates higher fuel vapor gradients near the droplets, leading to less intense evaporation and slower fuel transport in space.

An improved DSMC method for acoustic agglomeration of solid particles assisted by spray droplets

The direct simulation Monte Carlo (DSMC) method was improved for describing the process of acoustic agglomeration assisted by spray droplets. The agglomeration and rebound as consequences of inter-particle collisions were modeled by considering all possible particle types, in particular, mixed-phase particles associated with the immersion and distribution mechanisms. Numerical predictions by the present method were validated by both analytical solutions and experimental data. The dynamic process of the acoustic agglomeration in terms of the size and type evolution as well as the evolution of number concentration of different particle types were examined. Results suggest that the strong interaction between the solid particles and the spray droplets causes the significant enhancement of acoustic agglomeration. Furthermore, the effect of frequency varying from audible to ultrasonic range on the acoustic agglomeration was evaluated. Overall, a better performance of acoustic agglomeration can be achieved at a lower frequency, regardless of addition of spray droplets. Agglomeration efficiency of 64.8 % can be achieve at acoustic frequency of 1000 Hz in case with spray droplets. This study provides not only a numerical model for describing the agglomeration of complex particles in particle-laden gas flows, but also important insights into the acoustic agglomeration assisted by spray droplets.

Polydisperse sea spray effect on the vertical momentum transport in hurricanes

Abstract This study focuses on the influence of the sea spray polydispersity on the vertical transport of momentum in a turbulent marine atmospheric boundary layer in high-wind conditions of a hurricane. The Eulerian multifluid model treating air and spray droplets of different sizes as interacting inter-penetrating continua is developed and its numerical solutions are analyzed. Several droplet size distribution spectra and correlation laws relating wind speed and spray production intensity are considered. Polydisperse model solutions have confirmed the difference between the roles small and large spray droplets play in modifying the turbulent momentum transport that have been previously identified by monodisperse spray models. The obtained results have also provided a physical explanation for the previously unreported phenomenon of the formation of thin low-eddy-viscosity “sliding” layers in strongly turbulent boundary layer flows laden with predominantly fine spray.

Experimental investigation on effective aerosol scavenging using different spray configurations with pre-injection of water mist for Fukushima Daiichi decommissioning

During the decommissioning of the Fukushima Daiichi nuclear power plant, it is important to consider the retrieval of resolidified debris both in air and underwater configurations. For the subsequent retrieval of debris from the reactor building, the resolidified debris must be cut into smaller pieces using various cutting methods. During the cutting process, aerosol particles are expected to be generated at the submicron scale. It has been noted that such aerosols sizing within the Greenfield gap (0.1–1 μm) are difficult to remove effectively using traditional spraying methods. Therefore, to improve the aerosol removal efficiency of the spray system, a new aerosol agglomeration method was recently proposed, which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays. In this study, a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist. The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist. The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.

Parameterization scheme of the sea surface drag coefficient considering the influence of wave states and sea spray stress

The drag coefficient of the sea surface is crucial for the exchange of momentum between the ocean and atmosphere. The wave state significantly influences the variability of the drag coefficient. In the past, researchers commonly employed single-parameterization methods to describe this influence. However, the influence of wave conditions on drag coefficient is complex and variable, and it is difficult to accurately describe it with a single parameter alone. Wave age represents the ability of wind-induced waves to input energy, while wave steepness reflects the stability of the waves. By simultaneously considering wave age and wave steepness, a more accurate characterization of the dynamic nature of waves can be achieved. Additionally, the presence of sea spray profoundly impacts the distribution of the momentum flux between the ocean and atmosphere, thereby influencing the drag coefficient of the sea surface. In this study, we established a novel sea spray generation function that bases on both the wind speed and wave states (wave steepness and wave age). Considering this function, the momentum flux of sea spray droplets was analyzed under different wave states. Moreover, with increasing wave age or wave steepness, the effective sea surface drag coefficient is attenuated at low to moderate wind speeds. Considering the challenge of simultaneously obtaining wave age and wave steepness data, this paper proposes a relationship equation between the two wave state parameters. When the wave age is greater than 0.4, the correlation between the wave age and the wave steepness is strong. As the wind speed increases from low to high, there is a noticeable decrease in the effective sea surface drag coefficient with the corresponding increase in wave age. When the wave age is less than 0.4, the wave steepness reaches a maximum value, and the effective sea surface drag coefficient increases with the increase of the wave age at medium and low wind speed. With further increases in wind speed, the momentum flux derived from the air also increases. Simultaneously, the effective sea surface drag coefficient exhibits a decrease as wave age increases.

Benefits of ULV Application to Control Locusts in Caucasus and Central Asia

This paper discusses the state-of-the-art of Ultra-Low Volume (ULV) spray application with rotary atomisers in the Caucasus and Central Asian (CCA) region to control locusts. The technology is widely used around the world for locust control and promoted by the UN Food and Agriculture Organisation (FAO) as an effective and efficient control intervention that meets the scale and challenge posed by large area locust outbreaks. The technology utilises precisely controlled spray droplets in the range 50–100um using ready-to-use oil-based ULV formulations to target locusts more efficiently. Volume rates as low as 0.5–1.0 l/ha are utilised which greatly improves productivity of ground and aerial spray applications, timeliness, and reduces cost and waste of pesticide and water. ULV has become more widely adopted in CCA during recent years to control major economic pests such as Moroccan, Italian, and Asian migratory locusts. Its further adoption is hampered by the lack of available ULV formulations in the region and need for investment and training in the technology. ULV technology is highly appropriate for use of biological products to reduce risks to operators and the environment and efforts to increase regional cooperation and the registration of safer pesticides across the region present opportunities for its wider adoption.

CFD-EDEM simulations of droplets in an airless rotary spray coating process

Numerical simulations of airless rotary spray coating process are presented using CFD-EDEM with JKR contact model. The JKR model parameters are suggested according to the virtual test of accumulation angles in the funnel device. The reasonable droplet-wall surface energy is recommended from a relation of accumulation angles. The gas turbulence model is evaluated based on the comparisons of velocities and droplet number fractions using RNG k-ε, realizable k-ε and transition SST models. The simulated film thicknesses agree with measurements in literature. The correlation of exit droplet velocity of sprayer holes is proposed with a discharge coefficient of 2.27. The velocities and film thickness are predicted with changing rotation speeds. The normal force is an order of magnitude larger than the tangential force of droplet-wall collisions, and the ratio of the normal to tangential energy losses of droplet-wall collisions varies from 2.0 to 5.0 in airless rotary spray coating processes.

Depth from defocus technique: a simple calibration-free approach for dispersion size measurement

Particle size measurement is crucial in various applications, be it sizing droplets in inkjet printing or respiratory events, tracking particulate ejection in hypersonic impacts or detecting floating target markers in free-surface flows. Such systems are characterised by extracting quantitative information like size, position, velocity and number density of the dispersed particles, which is typically non-trivial. The existing methods like phase Doppler or digital holography offer precise estimates at the expense of complicated systems, demanding significant expertise. We present a novel volumetric measurement approach for estimating the size and position of dispersed spherical particles that utilises a unique ‘Depth from Defocus’ (DFD) technique with a single camera. The calibration-free sizing enables in situ examination of hard to measure systems, including naturally occurring phenomena like pathogenic aerosols, pollen dispersion or raindrops. The efficacy of the technique is demonstrated for diverse sparse dispersions, including dots, glass beads and spray droplets. The simple optical configuration and semi-autonomous calibration procedure make the method readily deployable and accessible, with a scope of applicability across vast research horizons.

Air Assistance and Electrostatic Spraying in Soybean Crops

This study aimed to evaluate the efficiency of air assistance associated with electrostatic spraying in terms of spray deposition and yield (Experiment 1), and the coverage and droplet density on soybean crops at different working speeds (Experiment 2). The treatments in Experiment 1 corresponded to combinations of electrostatic systems associated with air assistance at three airspeeds (21, 25, and 30 m·s−1) plus a conventional treatment without electrostatic or air assistance. The treatments in Experiment 2 corresponded to three working speeds (3.3, 4.2, and 5.0 m·s−1) with or without the use of an electrostatic system. All applications were performed with a self-propelled sprayer, delivering 75 L·ha−1 with ATR 2.0 nozzles. A blue tracer, detectable as absorbance with a spectrophotometer, was added to the spray solution to evaluate deposition. The results indicate that an air assistance at 21 m·s−1 plus electrostatic system increased the amount of spray deposited on the middle and top leaves of the plants in relation to the conventional system, with yield increments of up to 621 kg·ha−1. The slowest working speed (3.3 m·s−1) combined with air assistance and an electrostatic system provided the greatest spray deposition, droplet coverage, and density on the bottom leaves of soybean crops.

Effect of the Flow Passage Area Ratio on a Double Slit-Type Pintle Injector

Due to the structural characteristics of the pintle injector, a recirculation zone is generated under the pintle, so the pintle tip is directly exposed to a high-temperature environment. Therefore, the cooling technique and protective coating on the pintle tip are essential for improving the reusability and durability of the pintle injector. Although various cooling methods are known, this study applied a forced flow passage cooling method by adding internal structures called inserts to the pintle injector. The characteristics of the insert were analyzed experimentally and numerically based on change of its area ratio. When the internal flow changes, the spray angle, droplet size, and cooling performance also change in accordance with an increase in the insert’s central area. When the insert structure is installed in the pintle post, upward flow may occur, which can worsen the spray angle and droplet distribution characteristics. Nevertheless, owing to the insert structure, the surface temperature of the pintle post is reduced dramatically as intended. Thus, an optimal design technique for cooling by changing the area ratio of the first- and second-row slits of the pintle post can be suggested to overcome the limitations of the insert structure. The results of this study will be helpful in understanding the spray characteristics of the insert structure and optimize the design of cooling channels for reusable pintle injectors in the future.

Large Eddy Simulation of a Turbulent Polydisperse Spray Flow: A Comparative Study of Subgrid Scale Models and Droplet Injection Models

Abstract This study performs an investigation of the effects of the subgrid-scale (SGS) and droplet injection models in the large eddy simulation (LES) of turbulent two-phase spray flows. Three LES SGS models (Smagorinsky, wall-adapting local eddy viscosity (WALE), and dynamic Smagorinsky) and two droplet injection models (cone nozzle injection and conditional droplet injection) are validated to the experimental measurements. For both gaseous and liquid phases, all SGS models provide comparable results, indicating that the current two-phase flow field does not exhibit a pronounced sensitivity to the LES SGS model. As for different droplet injection models and spray dispersion angles, minimal differences are observed in the prediction of the gaseous mean and root-mean-square (RMS) velocity profiles. However, for the result of liquid phase, CDIM (conditional droplet injection model) predictions of the droplet mean diameter and velocity are in better agreement with experiments, and less sensitive to spray dispersion angle settings. While the CNIM (cone nozzle injection model) prediction of droplet diameter is less accurate when increasing the dispersion angle. The study suggests that turbulent two-phase spray flows are more influenced by the spray boundary conditions rather than the LES SGS models.

A Phenomenological Thermal Spray Wall Interaction Modeling Framework Applied to a High-Temperature Ignition Assistant Device

Abstract Airborne compression ignition engines must operate with reliable ignition systems to achieve proper ignition at every cycle, particularly at high altitudes. Glow-plug-based ignition-assistant (IA) devices can provide the necessary energy to preheat the fuel and ensure ignitability of the fuel-air mixture. Ignitability of liquid sprays can be facilitated via direct impingement onto the hot IA surface, however this comes with adverse effects on the IA durability. Therefore, optimizing an IA's design requires detailed understanding of the physics of fuel spray impingement of superheated surfaces. While spray impingement on relatively low wall temperatures has been extensively studied and appropriate numerical models have been proposed through the years, fundamental understanding of high-speed liquid spray impingement on superheated walls is still elusive. This work aims to formulate a phenomenological thermal spray-wall interaction framework for modeling the film-boiling-induced heat transfer, atomization, and dispersion of fuel spray droplets impinging onto a superheated IA device. A qualitative comparison of the new phenomenological model is performed against optical experiments from the literature of an F-24 fuel spray injected onto an IA device located 12 mm away from the injector tip. The temperature of the IA was set at 1400 K. The fuel injection pressure was 400 bar, while the ambient gas pressure and temperature were 30 bar and 800 K, respectively. The performance of the phenomenological model is evaluated in comparison with two other state-of-art models from the literature. A qualitative analysis of the different spray and fuel-air mixture characteristics is performed to outline the differences in the predictions offered by the new phenomenological model and the two state-of-art spray-wall interaction models.

Experimental Study of Spray and Combustion Characteristics in Gas-Centered Swirl Coaxial Injectors: Influence of Recess Ratio and Gas Swirl

The spray and combustion characteristics of a gas-centered swirl coaxial (GCSC) injector used in oxidizer-rich staged combustion cycle engines were analyzed. The study focused on varying the recess ratio, presence of gas swirl, and swirl direction to improve injector performance. The impact of the recess ratio was assessed by increasing it for gas jet-type injectors with varying momentum ratios. Gas-swirl effects were studied by comparing injectors with and without swirl against a baseline of a low recess ratio gas injection. In atmospheric pressure-spray experiments, injector performance was assessed using backlight photography, cross-sectional imaging with a structured laser illumination planar imaging technique (SLIPI), and droplet analysis using ParticleMaster. Increasing the recess ratio led to reduced spray angle and droplet size, and trends of gas swirl-type injectors were similar to those of high recess ratio gas jet-type injectors. Combustion tests involved fabricating combustion chamber heads equipped with identical injectors, varying only the injector type. Oxidizer-rich combustion gas, produced by a pre-burner, and kerosene served as propellants. Combustion characteristics, including characteristic velocity, combustion efficiency, and heat flux, were evaluated. Elevated recess ratios correlated with increased characteristic velocity and reduced differences in the momentum–flux ratios of injectors. However, increasing the recess ratio yielded diminishing returns on combustion efficiency enhancement beyond a certain threshold. Gas swirling did not augment characteristic velocity but notably influenced heat flux distribution. The trends observed in spray tests were related to combustion characteristics regarding heat flux and combustion efficiency. Additionally, it was possible to estimate changes in the location and shape of the flame according to the characteristics of the injector.

Cotton (Gossypium hirsutum) Response to Plant Protection Products using Different Spray Nozzles

Application of dicamba to dicamba-tolerant cotton (Gossypium hirsutism L.) cultivars (Xtend Cotton, Bayer Crop Science, Research Triangle Park, NC) requires use of nozzles that deliver large spray droplets to avoid off-site movement through particle drift onto susceptible crops and other plants including endangered species. Twenty trials over a three-year period were conducted to determine if nozzles required to deliver dicamba plus glyphosate would be equally effective in delivering other pesticides including the herbicide glufosinate, the plant growth regulator mepiquat chloride, the insecticide bifenthrin plus dichrotophos and co-application of ethephon plus thidiazuron plus tribufos for removal of cotton foliage to improve harvest efficiency. Agrichemicals were applied using: a) Air Induction (AI) nozzles for agrichemicals except dicamba plus glyphosate b) Turbo Teejet Induction (TTI) nozzles for all agrichemicals c) TTI nozzles for glufosinate and dicamba plus glyphosate and AI nozzles for other agrichemicals. Applications were made in 145 L/ha at 152 kPa at a ground speed of 5 km/h. Cotton height at the end of the season, node above first fruiting branch, nodes above cracked boll, node of uppermost boll, total nodes, lint yield, and cotton fiber quality were similar regardless of nozzles used to deliver agrichemcials. Control of a complex of broadleaf signal grass (Urochloa platyphylla L.), goosegrass [Eleusine indica (L.) Gaert.], and large crabgrass (Digitaria sanguinalis L.) and Palmer amaranth (Amaranthus palmeri Watts.) was slightly lower when glufosinate was applied with TTI nozzles rather than AI nozzles. However, control of these weeds was similar regardless of nozzle selection when dicamba plus glyphosate was applied after glufosinate. These results suggest that growers can use nozzles that limit off-site movement through particle drift of agrichemicals throughout the cropping cycle with no major adverse effect on weed control and cotton growth and yield.

Spray performance of flexible shield canopy opener and rotor wind integrated boom-sprayer application in soybean: effects on droplet deposition distribution.

Canopy density is high during mid-to-late soybean growth as a result of dense planting to improve yield, which seriously affects the control of pests and diseases. The dilemmas of difficult droplet penetration, nonuniform deposition, and droplet drift in field spraying remain challenges to the precise control of droplet distribution. This paper proposed a novel spraying application mode combined flexible shield canopy opener (FSCO) with rotor wind. The design of the key components of the new boom-spraying machine are described. The effects of the comparative spraying modes on spray deposition and droplet drift were studied in a field validation test to explore the feasibility of the novel spraying application. The study found that droplet coverage inside the soybean canopy was significantly affected by spraying mode, rotor wind speed and opener depth. The spraying operation that used the FSCO and rotor wind integrated mode was optimal for droplet uniformity on the adaxial and abaxial surfaces of the canopy leaves, with droplet uniformity indices of 0.966 and 0.934, respectively. At a rotor wind speed of 6 m s-1 and opener depth of 15 cm, the soybean canopy droplet coverage uniformity effect achieved the highest composite score of 0.937. The spraying mode used in this study improved droplet coverage uniformity by 82.30% and droplet anti-drift performance improved by 99.73% compared to the conventional boom-spraying mode. The study shows validity of the spraying mode combined FSCO with rotor wind to open dense canopy and improved droplet deposition uniformity in canopy and anti-drift performance. © 2024 Society of Chemical Industry.

Gas–liquid twin-fluid atomization from non-circular orifices

Passive control of twin-fluid atomization can be achieved by changing the orifice shape of the injector. In this study, the characteristics of twin-fluid atomization in the outside-in-liquid injector with circular, square, and rectangular orifices at various aspect ratios were investigated experimentally and computationally. The morphology of the spray was captured by shadowgraph, the diameter and velocity of the droplets were measured by the phase Doppler particle analyzer, and numerical simulations were performed for the central gaseous core. Comparing the sprays with square and circular orifices, droplets from the non-circular orifice are generally smaller with less disparities in droplet sizes due to the more intensive turbulent disturbances and corner effect. Furthermore, the non-circular orifice also results in better spatial distribution of the spray. The droplet diameters of the spray with a square orifice do not satisfy the log-normal distribution near the orifice along the centerline of the spray, which may be attributed to the different entrainment of spray droplets by the central gas flow for the sprays with circular and non-circular orifices. The twin-fluid sprays produced by the rectangular orifice also exhibit the same axial switching effect as in the high-pressure gaseous jet flow, in which the spray diffusion in the minor axis is more extensive than that in the major axis. Moreover, the droplets' Sauter mean diameter produced by the rectangular orifice is more sensitive to the size in the minor axis of the orifice and decreases as the aspect ratio of the orifice increases given the same cross-sectional area.

A CFD-DEM Simulation of Droplets in an Airless Spray Coating Process of a Square Duct

The purpose of this paper is to provide a numerical simulation, taking into account the collisional interactions of droplets in an airless rotary spray coating process. The hydrodynamics of gas and droplets are simulated using the CFD-discrete element method (DEM) with the JKR contact model in an airless rotary spray coating process of a horizontal square duct. The surface energy parameter used in the JKR model is calibrated using a virtual accumulation angle test in the funnel device. Based on the distribution of accumulation angles, a suitable surface energy for wall droplets is proposed. A rational gas RNG k-ε model is suggested in accordance with the comparisons of velocities, standard deviations, and the skewness of droplet number fractions from three turbulence models. The simulations of droplet film thicknesses agree with measurements from the literature regarding the film thickness along a vertical panel. The correlations of the exit gas and droplet velocities of sprayer holes are proposed with a discharge coefficient of 0.85 for gas and 5.87 for droplets. A number index of droplets is introduced in order to measure the uniformity of droplet distributions. A low droplet number index is found at low rotational speeds, representing a more uniform distribution of droplets as the rotation speeds reduce within the square duct. The normal force between the droplet and the wall is approximately an order of magnitude larger than the droplet–wall tangential force of collisions.

Numerical investigations on the droplet moving in steam with non-condensable gas by lattice Boltzmann method

Spray cooling is an efficient cooling technology with high heat dissipation, and has been extensively utilized in various industry areas. The interaction mechanism between the spray droplet and environmental space with high pressure and temperature is extremely complex, especially with non-condensable gas. In this paper, a pseudopotential multicomponent multiphase lattice Boltzmann model for droplet migration with non-condensable gas in high temperature and pressure was proposed. The mechanism of transfer characteristics for droplet in steam were studied. It is found that the mass transfer of droplet is controlled by density and condensation, droplet growth is mainly impacted by density at initial stage, and in later period, the growth is greatly weakened by the condensation suppression of non-condensable gas. The calculated results show that when Fo > 0.4, mass transfer is significantly decreased. Heat transfer is also affected by non-condensable gas, and 2% gas declines the droplet heat transfer rate by about 10%. It is also found that the mass transfer rate is approximately linearly associated with the ratio of non-condensable gas content inside and outside the droplet. The results can be used for development of spray cooling model, and have positive guiding significance for optimizing spray cooling system.

Gas–liquid coaxial atomization with swirl in high-pressure environments

We present recent experimental results on the dynamics of atomization of a liquid column by a coaxial turbulent gas jet, under varying air angular momentum (swirl) conditions and densities. We compare between atomization under atmospheric conditions and in a pressurized environment where the atomizing and ambient air density is 5 times the atmospheric level. For both conditions, the parameter space includes a gas-to-liquid momentum ratio in the range of M=25−56 and swirl ratios of SR=0−1. High-speed shadowgraphy images in the spray near-field are used to quantify the spatial and temporal evolution of the liquid–gas interface. In the mid-field, Phase Doppler Interferometry, collected radially across the spray, quantify droplet size, velocity, and number density distributions. At high pressure and with increasing M, we observe a decrease in spray angle when SR=0 but a spray angle increase when SR>0.5 (critical swirl). We reconcile these observations with the crown de-wetting mechanism, first observed in X-ray shadowgraphs of the spray. Crown de-wetting depends on gas inertia relative to the liquid, which increases linearly with atomization environment pressure, leading to this switch in behavior. This mechanism also explains the modified droplet radial distribution in the mid-field, with critical transition from concave to convex-shaped trends in the mean droplet size profile. Finally, we reconstruct the full spray droplet population from radial measurements, showing that swirl not only modifies the transport of droplets in the spray cross-section, but also enhances break-up and reduces the Sauter Mean Diameter globally, for all momentum ratios and pressure conditions tested.

3D analysis of spray effect on long-term depressurization of VVER-1000 containment during LB-LOCA

Containment as the last barrier of defence in depth strategy plays the most important role in protecting the environment and public from the release of radioactive material. As a result, analysing its performance in nuclear accidents and the reliability and effectiveness of its engineering safety features (ESFs) in the depressurization of containment is a key step in safety assessment. This study demonstrates the effect of the spray system as one of the ESFs in long-term depressurization of VVER-1000 containment during an LB-LOCA accident by using GOTHIC code. In the first step toward this goal, the as-built 3D structure of VVER-1000/V446 containment has been prepared in AutoCAD and used as GOTHIC geometry input by applying the input preparation process. Long-term 3D profiles of temperature and pressure were simulated in GOTHIC without spray actuation. The next step deals with considering the effects of spray and sensitivity analysis of spray temperature and droplet diameter on long-term depressurization. 3D profiles of thermal-hydraulic parameters during long-term depressurization of containment have been presented as research outcomes and validated against FSAR data and finally, the effects of spray on profiles were concluded. Results can obviously prove the effect of spray on the long-term depressurization of containment. The required time to achieve half of the peak pressure of the containment was calculated as 1380 s which is completely in agreement with NRC safety criteria. Research outcomes confirm the success of the spray system to support the integrity of containment which could be jeopardized without spray system intervention.