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1
Kapusta, Łukasz Jan, Jakub Bachanek, Changzhao Jiang, Jakub Piaszyk, Hongming Xu, and Mirosław Lech Wyszyński. "Liquid Propane Injection in Flash-Boiling Conditions." Energies 14, no. 19 (October 1, 2021): 6257. http://dx.doi.org/10.3390/en14196257.
Повний текст джерелаАнотація:
This study aimed to investigate the influence of flash-boiling conditions on liquid propane sprays formed by a multi-hole injector at various injection pressures. The focus was on spray structures, which were analysed qualitatively and quantitatively by means of spray-tip penetration and global spray angle. The effect of flash boiling was evaluated in terms of trends observed for subcooled conditions. Propane was injected by a commercial gasoline direct injector into a constant volume vessel filled with nitrogen at pressures from 0.1 MPa up to 6 MPa. The temperature of the injected liquid was kept constant. The evolution of the spray penetration was observed by a high-speed camera with a Schlieren set-up. The obtained results provided information on the spray evolution in both regimes, above and below the saturation pressure of the propane. Based on the experimental results, an attempt to calibrate a simulation model has been made. The main advantage of the study is that the effects of injection pressure on the formation of propane sprays were investigated for both subcooled and flash-boiling conditions. Moreover, the impact of the changing viscosity and surface tension was limited, as the temperature of the injected liquid was kept at the same level. The results showed that despite very different spray behaviours in the subcooled and flash-boiling regimes, leading to different spray structures and a spray collapse for strong flash boiling, the influence of injection pressure on propane sprays in terms of spray-tip penetration and spray angle is very similar for both conditions, subcooled and flash boiling. As for the numerical model, there were no single model settings to simulate the flashing sprays properly. Moreover, the spray collapse was not represented very well, making the simulation set-up more suitable for less superheated sprays.
2
Hardalupas, Y., and J. H. Whitelaw. "Interaction Between Sprays From Multiple Coaxial Airblast Atomizers." Journal of Fluids Engineering 118, no. 4 (December 1, 1996): 762–71. http://dx.doi.org/10.1115/1.2835507.
Повний текст джерелаАнотація:
Phase Doppler measurements of size, velocity, liquid flux, and average mass fractions were obtained in sprays produced by three identical coaxial airblast atomizers, with their axes placed in a triangular arrangement at distances of two air jet diameters from each other; the arrangement simulates the spray interaction in the preburner of the space shuttle main engine with water and air respectively replacing the liquid oxygen and hydrogen of the preburner sprays. Each nozzle comprised a liquid jet with exit diameter of 2.3 mm centred in a 8.95 mm diameter air stream. Two liquid flowrates were examined, while the air flowrate was kept constant, resulting in Weber number at the exit of the nozzle around 1100, air-to-liquid momentum ratio 8.6 and 38, velocity ratio 24 and 51, mass flowrate ratio 0.35 and 0.75, liquid jet Reynolds number 10,000 and 21,000 and air jet Reynolds number around 108,000. The air flow characteristics were compared to the flow without liquid injection. Up to 10 air jet diameters from the nozzle exit, individual spray characteristics dominated and maximum Sauter mean diameters, typically around 150 μm, and liquid flux were observed on the geometrical axes of the nozzles. Spray merging was strong in the region between the nozzle axes, where the Sauter mean diameter reduced and the liquid flux and the mean and rms of the fluctuations of the axial velocity of the droplets and the air flow increased relative to the single spray. Downstream of 25 air jet diameters from the nozzle exit, the multiple sprays merged to a single spray-like flow produced by a nozzle located at the centre of the triangular region between the nozzle axes. Reduction of the liquid flowrate by 50 percent, improved atomization by 25 percent, shortened the axial distance from the nozzles where the individual spray characteristics disappeared by 30 percent and increased the air flow turbulence by 20 percent. Droplet coalescence was negligible for high liquid flowrates, but for reduced liquid flowrates coalescence became important and the Sauter mean diameter increased with the axial distance from the exit by around 15 percent. Spray merging increased the air flow turbulence and the local mass fraction distribution of the air in the region between the nozzle axes by around 50 and 40 percent respectively relative to the single sprays, resulting in a fuel rich region with increased gas flow turbulence which may influence the ignition process in the preburner of the space shuttle main engine.
3
Post, Scott L., and Rory L. Roten. "A Review of the Effects of Droplet Size and Flow Rate on the Chargeability of Spray Droplets in Electrostatic Agricultural Sprays." Transactions of the ASABE 61, no. 4 (2018): 1243–48. http://dx.doi.org/10.13031/trans.12516.
Повний текст джерелаАнотація:
Abstract. The chargeability of liquid sprays is an important factor in determining the deposition efficiency of electrostatic pesticide sprays. The Rayleigh limit provides information on the maximum amount of charge a spray droplet can carry as a function of droplet size and liquid properties. This article reviews the literature to determine what fraction of the Rayleigh limit is achievable. Typically, less than 10% of the Rayleigh limit charge is obtained. The droplet charge per unit mass decreases with increasing droplet size and liquid flow rate. A correlation equation is derived from published data to predict spray droplet charge per unit mass from droplet size, flow rate, and charging voltage. Keywords: Droplet size, Electrostatic charging, Spray drift, Sprayers, Ultra-low volume spraying.
4
Goodwin, M. S., and G. Wigley. "A Study of Transient Liquid Sheets and Their Relationship to GDI Fuel Sprays(Spray Technologies, Atomization)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2004.6 (2004): 271–77. http://dx.doi.org/10.1299/jmsesdm.2004.6.271.
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5
Luo, Meng, Pingping Zhu, Usman Rana, Hu Ma, Zhendong Yu, and Oskar J. Haidn. "Modeling Investigation of Liquid Oxygen Flashing Spray with CFD." Journal of Physics: Conference Series 2235, no. 1 (May 1, 2022): 012061. http://dx.doi.org/10.1088/1742-6596/2235/1/012061.
Повний текст джерелаАнотація:
Abstract Injection of cryogenic propellants (e.g. liquid oxygen) into low-pressure environment (e.g. upper-stage rocket engine) may trigger flashing phenomenon, which severely affects the propellants’ mixing and combustion. In order to unveil the characteristics of flashing sprays, numerical models of flashing sprays were developed and validated. First, a developed model based on Adachi-correlation was employed for the flashing spray simulation. The results show good agreements with the experiments, both for the flashing spray morphology and temperature distribution. In the near-injector region, the flashing evaporation dominates the spray vaporization with the evaporation mass flow rate of about 2 orders of magnitude higher than that by the other heat transfers, whereas downstream the injector, the external heat transfer (i.e. heat conduction and convection) does. Furthermore, a new flashing spray model based on the nucleate boiling theory was proposed, which shows an improved agreement of the droplet temperature between the simulation and test data.
6
Poursadegh, Farzad, Oleksandr Bibik, Boni Yraguen, and Caroline L. Genzale. "A multispectral, extinction-based diagnostic for drop sizing in optically dense diesel sprays." International Journal of Engine Research 21, no. 1 (July 31, 2019): 15–25. http://dx.doi.org/10.1177/1468087419866034.
Повний текст джерелаАнотація:
Diesel sprays present a challenging environment for detailed quantitative measurement of the liquid field, and to date, there have been only a few efforts to characterize drop sizes within the family of Engine Combustion Network (ECN) diesel sprays. Drop sizing diagnostics, including optical microscopy and Ultra-Small Angle X-ray Scattering (USAXS), have been recently demonstrated in Spray A/D ECN activities, but little data exist to validate these results. This work therefore seeks to extend the available ECN data on the liquid phase field and provide a new comparative data set for assessment of previous ECN drop sizing measurements. In particular, this work presents the development of a two-wavelength, line-of-sight extinction measurement to examine liquid volume fraction and the corresponding droplet field in high-pressure fuel sprays. Here, extinction of lasers emitting at 10.6 μm and 0.633 μm are used for the measurement. To enable quantification of the liquid field in optically dense regions of the spray, a transfer function is developed to account for the influence of multiple scattering. The developed diagnostic is then applied to n-dodecane sprays from the ECN Spray A and Spray D injectors at varying fuel rail pressures and atmospheric chamber condition. Overall, the results show a reasonable agreement with droplet sizes measured using USAXS, as well as from more recent measurements using a Scattering-Absorption Measurement Ratio (SAMR) technique also developed in our group. This is particularly the case near the spray periphery, where on average, less than 40% difference in the measured Sauter mean diameter is observed. Nonetheless, an apparent discrepancy is observed between drop sizes from different diagnostics close to the jet centerline (i.e. nearly 100% difference between available data for Spray D injector). Moreover, the presented diagnostic shows an improved capability in the dilute regions of the spray, where x-ray-based diagnostics are generally subject to high noise and low signal sensitivity.
7
Shelton, A. M., W. T. Wilsey, and S. E. Webb. "Control of Fall Armyworm (FAW) by Aerial Applications of Liquid Insecticides, 1986." Insecticide and Acaricide Tests 12, no. 1 (January 1, 1987): 119–20. http://dx.doi.org/10.1093/iat/12.1.119a.
Повний текст джерелаАнотація:
Abstract One commercial field, located near Avon, NY, was used for this test. The field was divided into 4 sections and each section contained a subsection of 100 plants in the silking stage. On the silks of each of the 400 plants, 15 newly hatched FAW larvae were deposited on 3 Aug. On 5 Aug, each section was sprayed with 1 of 3 insecticides. Additional sprays of each insecticide were applied on 13 and 19 Aug. A spray of Penncap was substituted for the 19 Aug EPN spray because of PHI. A Grumman Air Cat, delivering 3 gal/acre, was used to apply the sprays. At harvest (29 Aug), 50 ears from each treatment were evaluated for damage.
8
Zhou, Xinyi, Tie Li, Yijie Wei, and Ning Wang. "Scaling liquid penetration in evaporating sprays for different size diesel engines." International Journal of Engine Research 21, no. 9 (December 6, 2019): 1662–77. http://dx.doi.org/10.1177/1468087419889835.
Повний текст джерелаАнотація:
Scaled model experiments can greatly reduce the cost, time and energy consumption in diesel engine development, and the similarity of spray characteristics has a primary effect on the overall scaling results of engine performance and pollutant emissions. However, although so far the similarity of spray characteristics under the non-evaporating condition has been studied to some extent, researches on scaling the evaporating sprays are still absent. The maximum liquid penetration length has a close relationship with the spray evaporation processes and is a key parameter in the design of diesel engine spray combustion system. In this article, the similarity of maximum liquid penetration length is theoretically derived based on the hypotheses that the spray evaporation processes in modern high-pressure common rail diesel engines are fuel–air mixing controlled and local interphase transport controlled, respectively. After verifying that the fuel injection rates are perfectly scaled, the similarity of maximum liquid penetration length in evaporating sprays is studied for three scaling laws using two nozzles with hole diameter of 0.11 and 0.14 mm through the high-speed diffused back-illumination method. Under the test conditions of different fuel injection pressures, ambient temperatures and densities, the lift-off law and speed law lead to a slightly increased maximum liquid penetration length, while the pressure law can well scale the maximum liquid penetration length. The experimental results are consistent with the theoretical analyses based on the hypothesis that the spray evaporation processes are fuel–air mixing controlled, indicating that the local interphase transports of energy, momentum and mass on droplet surface are not rate-controlled steps with respect to spray evaporation processes.
9
Jassim, Ahmad K., Basim A. Abd Alhay, Rakad K. Abd Al Kadhim, Fatima Kh Hato, and Dhaa A. Hashim. "A Comparison of Soybean Oil Methyl Ester and Diesel Sprays behavior and atomization characteristics." Journal of Petroleum Research and Studies 7, no. 1 (May 6, 2021): 59–72. http://dx.doi.org/10.52716/jprs.v7i1.162.
Повний текст джерелаАнотація:
The present numerical study compares between spray characteristics of diesel and soybean oil methyl ester (SME biodiesel) under non-evaporating sprays. The spray structure of diesel and biodiesel fuel (soybean oil) in a common rail injection system are investigated and compared with that of available experimental data used image processing and atomization performance analysis. The proposed approach for the liquid phase based on the statistical properties of sprays be used to describe the liquid and gas phases in an Eulerian-Eulerian approach. The main concept for this model is the possibility of describing a poly disperse spray by using moments of a drop number size distribution function. The main reason for less spray tip penetration in
the (SME) comparing with diesel because a larger droplet diameters is the higher density, viscosity and surface tension of (SME). The effect of fuel properties on the near nozzle structure is studied. The comparisons are referring that the spray drag, breakup and collision processes are promoted.
10
Jasim, Noor Mohsin. "A Comparison of Soybean Oil Methyl Ester and Diesel Sprays Behavior and Atomization Characteristics." Journal of Petroleum Research and Studies 7, no. 4 (May 7, 2021): 65–79. http://dx.doi.org/10.52716/jprs.v7i4.206.
Повний текст джерелаАнотація:
The present numerical study compares between spray characteristics of diesel and soybean oil methyl ester (SME biodiesel) under non-evaporating sprays. The spray structure of diesel and biodiesel fuel (soybean oil) in a common rail injection system are investigated and compared with that of available experimental data used image processing and atomization performance analysis. The proposed approach for the liquid phase, which based on the sprays’ statistical properties, is used to present the gas and liquid phases in an Eulerian-Eulerian approach. The main concept for this model is the possibility of describing a poly disperses spray by using moments of a drop number size distribution function. The main reason for less spray tip penetration in the (SME) comparing with diesel because a larger droplet diameters is the higher density, surface tension and viscosity of (SME). The fuel properties effect on the near nozzle structure is studied. The comparisons are referring that the spray drag, breakup and collision processes are promoted.
11
Kolanjiyil, Arun V., Ali Alfaifi, Ghali Aladwani, Laleh Golshahi, and Worth Longest. "Importance of Spray–Wall Interaction and Post-Deposition Liquid Motion in the Transport and Delivery of Pharmaceutical Nasal Sprays." Pharmaceutics 14, no. 5 (April 28, 2022): 956. http://dx.doi.org/10.3390/pharmaceutics14050956.
Повний текст джерелаАнотація:
Nasal sprays, which produce relatively large pharmaceutical droplets and have high momentum, are primarily used to deliver locally acting drugs to the nasal mucosa. Depending on spray pump administration conditions and insertion angles, nasal sprays may interact with the nasal surface in ways that creates complex droplet–wall interactions followed by significant liquid motion after initial wall contact. Additionally, liquid motion can occur after deposition as the spray liquid moves in bulk along the nasal surface. It is difficult or impossible to capture these conditions with commonly used computational fluid dynamics (CFD) models of spray droplet transport that typically employ a deposit-on-touch boundary condition. Hence, an updated CFD framework with a new spray–wall interaction (SWI) model in tandem with a post-deposition liquid motion (PDLM) model was developed and applied to evaluate nasal spray delivery for Flonase and Flonase Sensimist products. For both nasal spray products, CFD revealed significant effects of the spray momentum on surface liquid motion, as well as motion of the surface film due to airflow generated shear stress and gravity. With Flonase, these factors substantially influenced the final resting place of the liquid. For Flonase Sensimist, anterior and posterior liquid movements were approximately balanced over time. As a result, comparisons with concurrent in vitro experimental results were substantially improved for Flonase compared with the traditional deposit-on-touch boundary condition. The new SWI-PDLM model highlights the dynamicenvironment that occurs when a nasal spray interacts with a nasal wall surface and can be used to better understand the delivery of current nasal spray products as well as to develop new nasal drug delivery strategies with improved regional targeting.
12
Jazayeri, Seyed A., and Xianguo Li. "Structure of Liquid-Sheet Sprays." Particle & Particle Systems Characterization 17, no. 2 (June 2000): 56–65. http://dx.doi.org/10.1002/1521-4117(200006)17:2<56::aid-ppsc56>3.0.co;2-0.
Повний текст джерела
13
Panão, Miguel. "Ultrasonic Atomization: New Spray Characterization Approaches." Fluids 7, no. 1 (January 7, 2022): 29. http://dx.doi.org/10.3390/fluids7010029.
Повний текст джерелаАнотація:
In particle engineering, spray drying is an essential technique that depends on producing sprays, ideally made of equal-sized droplets. Ultrasonic sprays appear to be the best option to achieve it, and Faraday waves are the background mechanism of ultrasonic atomization. The characterization of sprays in this atomization strategy is commonly related to the relation between characteristic drop sizes and the capillary length produced by the forcing frequency of wavy patterns on thin liquid films. However, although this atomization approach is practical when the intended outcome is to produce sprays with droplets of the same size, drop sizes are diverse in real applications. Therefore, adequate characterization of drop size is paramount to establishing the relations between empirical approaches proposed in the literature and the outcome of ultrasonic atomization in actual operating conditions. In this sense, this work explores new approaches to spray characterization applied to ultrasonic sprays produced with different solvents. The first two introduced are the role of redundancy in drop size measurements to avoid resolution limitation in the measurement technique and compare using regular versus variable bin widths when building the histograms of drop size. Another spray characterization tool is the Drop Size Diversity to understand the limitations of characterizing ultrasonic sprays solely based on representative diameters or moments of drop size distributions. The results of ultrasonic spray characterization obtained emphasize: the lack of universality in the relation between a characteristic diameter and the capillary length associated with Faraday waves; the variability on drop size induced by both liquid properties and flow rate on the atomization outcome, namely, lower capillary lengths produce smaller droplets but less efficiently; the higher sensibility of the polydispersion and heterogeneity degrees in Drop Size Diversity when using variable bin widths to build the histograms of drop size; the higher drop size diversity for lower flow rates expressed by the presence of multiple clusters of droplets with similar characteristics leading to multimodal drop size distributions; and the gamma and log-normal mathematical probability functions are the ones that best describe the organization of drop size data in ultrasonic sprays.
14
Nourian, Amir, Ghasem G. Nasr, Andrew J. Yule, Gary Hawthorne, and Tom Goldberg. "Novel metered aerosol valve." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 10 (February 17, 2015): 1557–68. http://dx.doi.org/10.1177/0954406215572839.
Повний текст джерелаАнотація:
The design and performance of a new valving mechanism for portable pressurized spraying devices is described, where the propellant in the device is a safe gas (so-called compressed gas) propellant rather than the current liquefied gases all of which are either volatile organic compounds or greenhouse gases. The valve sprays a fixed volume of liquid when the spraying actuator is depressed, as is essential used medical sprays, such as pressurized metered dose inhalers and nasal sprays, and also for automatic (wall-mounted) aerosol delivery systems for air-fresheners, insecticides and disinfectants. For ‘compressed gas’ aerosol formats, there is no flash vaporization of propellant so that pumping liquid from a metering chamber and atomization to form a spray must be achieved entirely by designing some means of using the pumping action of the gas in the container to act upon the liquid in the metering chamber. The new design utilizes a loosely fitting spherical piston element and a simple arrangement of a concentric housing and a moveable valve stem, such that liquid flow paths between the different elements are automatically closed and opened in the correct time sequence when the valve stem is depressed and released. Spraying data show excellent repeatability of liquid sprayed per pulse throughout the lifetime of device and drop sizes that are acceptable for devices such as air-fresheners and nasal sprays. The valve has only one additional component compared with liquefied gas metered valves and can be straightforwardly injection moulded. As will be explained, previous attempts failed due to expense, complexity and unreliability.
15
Zhang, Zhen, and Dong-hyuk Shin. "Effect of ambient pressure oscillation on the primary breakup of cylindrical liquid jet spray." International Journal of Spray and Combustion Dynamics 12 (January 2020): 175682772093555. http://dx.doi.org/10.1177/1756827720935553.
Повний текст джерелаАнотація:
The present simulation study investigates the effects of ambient pressure oscillation on cylindrical liquid jet sprays, using the volume of fluid method. The research is motivated by combustion instability in combustion engines, where strong harmonic pressure oscillation can damage internal structures. Oscillating pressure modulates not only the fuel mass flow rate but also the ambient gas density and liquid surface tension, and in liquid sprays, the ambient fluid density and surface tension can have substantial effects on spray breakup. In order to investigate the multiple property changes with ambient pressure oscillation, therefore, a new solver in OpenFOAM is developed. In the solver, liquid mass flow rate, ambient gas density, and liquid surface tension change simultaneously as a result of pressure oscillation. Simulations were conducted at a Reynolds number of 2000 and Weber number over 2000, conditions that are conducive to primary breakup in laminar flows. The simulations show that oscillations in ambient pressure significantly strengthen the surface instability of the liquid ligament, which depends on the surface tension–pressure coefficient, the mean pressure, and the amplitude of oscillation.
16
Sirignano, William A. "Fluid Dynamics of Sprays—1992 Freeman Scholar Lecture." Journal of Fluids Engineering 115, no. 3 (September 1, 1993): 345–78. http://dx.doi.org/10.1115/1.2910148.
Повний текст джерелаАнотація:
Various theoretical and computational aspects of the fluid dynamics of sprays are reviewed. Emphasis is given to rapidy vaporizing sprays on account of the richness of the scientific phenomena and the several, often disparate, time scales. Attention is given to the behavior of individual droplets including the effects of forced convection due to relative droplet-gas motion, Stefan convection due to the vaporization or condensation of the liquid, internal circulation of the liquid, interactions with neighboring droplets, and interactions with vortical eddies. Flow field details in the gas boundary layer and wake and in the liquid droplet interior are examined. Also, the determinations of droplet lift and drag coefficients and Nusselt and Sherwood numbers and their relationships with Reynolds number, transfer number, Prandtl and Schmidt numbers, and spacing between neighboring droplets are extensively discussed. The spray equations are examined from several aspects; in particular, two-continua, multi-continua, discrete-particle, and probabilistic formulations are given. The choice of Eulerian or Lagrangian representation of the liquid-phase equations within these formulations is discussed including important computational issues and the relationship between the Lagrangian method and the method of characteristcis. Topics for future research are suggested.
17
Stumpf, Bastian, Jeanette Hussong, and Ilia V. Roisman. "Drop Impact onto a Substrate Wetted by Another Liquid: Flow in the Wall Film." Colloids and Interfaces 6, no. 4 (October 20, 2022): 58. http://dx.doi.org/10.3390/colloids6040058.
Повний текст джерелаАнотація:
The impact of a drop onto a liquid film is relevant for many natural phenomena and industrial applications such as spray painting, inkjet printing, agricultural sprays, or spray cooling. In particular, the height of liquid remaining on the substrate after impact is of special interest for painting and coating but also for applications involving heat transfer from the wall. While much progress has been made in explaining the hydrodynamics of drop impact onto a liquid film of the same liquid, the physics of drop impact onto a wall film with different material properties is still not well understood. In this study, drop impact onto a very thin liquid film of another liquid is investigated. The thickness of the film remaining on a substrate after drop impact is measured using a chromatic-confocal line sensor. It is interesting that the residual film thickness does not depend on the initial thickness of the wall film, but strongly depends on its viscosity. A theoretical model for the flow in the drop and wall film is developed which accounts for the development of viscous boundary layers in both liquids. The theoretical predictions agree well with the experimental data.
18
Gavaises, M., A. Theodorakakos, G. Bergeles, and G. Brenn. "Evaluation of the Effect of Droplet Collisions on Spray Mixing." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 210, no. 5 (September 1996): 465–75. http://dx.doi.org/10.1243/pime_proc_1996_210_220_02.
Повний текст джерелаАнотація:
A spray model, implemented in a three-dimensional computational fluid dynamics (CFD) code has been used to evaluate the effect of droplet collisions on spray mixing resulting from the overlapping of liquid spray cones produced by two parallel hollow-cone nozzles under the influence of a cross-flow. The computations are compared with experimental results from phase Doppler anemometer (PDA) measurements in mixing steady sprays. The results show that the droplet collisions, which mainly occur in the mixing area of the two different sprays, have great influence on the droplet size and, as a consequence, on the predicted droplet velocities, especially at distances far from the spray nozzles. Information about the collision mechanisms as well as about droplet velocities and droplet dispersion due to collisions is also presented.
19
Yule, A. J., and D. G. Salters. "On the Distance Required to Atomize Diesel Sprays Injected from Orifice-Type Nozzles." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 209, no. 3 (July 1995): 217–26. http://dx.doi.org/10.1243/pime_proc_1995_209_205_02.
Повний текст джерелаАнотація:
Conductivity probe measurements, using ranges of nozzles, liquid properties and gas densities, have revealed more extensive and reliable information on the break-up process of diesel sprays than has been published to date. The spray generated from a single-hole orifice-type nozzle has an incompletely atomized break-up length which typically extends at least 100 hole diameters downstream. The physical structure of this break-up zone varies, depending on the liquid properties and both initial and boundary conditions, from that of a central liquid column, with outer drops and ligaments, to, more typically, that of a chaotic ‘wire wool’ structure of ligaments and drops. Time variations of the break-up length are found during spray pulses and concentrations of poorly atomized liquid are convected downstream in the form of coherent structures. The existence of this zone has repercussions with respect to spray-gas flow interaction, fuel vaporization and wall wetting in internal combustion engines.
20
MELTON, LYNN A., and JAMES F. VERDIECK. "Vapor/Liquid Visualization for Fuel Sprays." Combustion Science and Technology 42, no. 3-4 (January 1985): 217–22. http://dx.doi.org/10.1080/00102208508960379.
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Melton, Lynn A., and James F. Verdieck. "Vapor/liquid visualization in fuel sprays." Symposium (International) on Combustion 20, no. 1 (January 1985): 1283–90. http://dx.doi.org/10.1016/s0082-0784(85)80618-4.
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22
Lee, Suk Ho. "Group vaporization of liquid fuel sprays." KSME Journal 4, no. 1 (March 1990): 62–70. http://dx.doi.org/10.1007/bf02953392.
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23
Seifelnasr, Amr, Mohamed Talaat, Pranav Ramaswamy, Xiuhua April Si, and Jinxiang Xi. "A Supine Position and Dual-Dose Applications Enhance Spray Dosing to the Posterior Nose: Paving the Way for Mucosal Immunization." Pharmaceutics 15, no. 2 (January 20, 2023): 359. http://dx.doi.org/10.3390/pharmaceutics15020359.
Повний текст джерелаАнотація:
Delivering vaccines to the posterior nose has been proposed to induce mucosal immunization. However, conventional nasal devices often fail to deliver sufficient doses to the posterior nose. This study aimed to develop a new delivery protocol that can effectively deliver sprays to the caudal turbinate and nasopharynx. High-speed imaging was used to characterize the nasal spray plumes. Three-dimensional-printed transparent nasal casts were used to visualize the spray deposition within the nasal airway, as well as the subsequent liquid film formation and translocation. Influencing variables considered included the device type, delivery mode, release angle, flow rate, head position, and dose number. Apparent liquid film translocation was observed in the nasal cavity. To deliver sprays to the posterior nose, the optimal release angle was found to be 40° for unidirectional delivery and 30° for bidirectional delivery. The flow shear was the key factor that mobilized the liquid film. Both the flow shear and the head position were important in determining the translocation distance. A supine position and dual-dose application significantly improved delivery to the nasopharynx, i.e., 31% vs. 0% with an upright position and one-dose application. It is feasible to effectively deliver medications to the posterior nose by leveraging liquid film translocation for mucosal immunization.
24
Yue, Zongyu, and Rolf D. Reitz. "An equilibrium phase spray model for high-pressure fuel injection and engine combustion simulations." International Journal of Engine Research 20, no. 2 (December 6, 2017): 203–15. http://dx.doi.org/10.1177/1468087417744144.
Повний текст джерелаАнотація:
High-pressure fuel injection impacts mixture preparation, ignition and combustion in engines and other applications. Experimental studies have revealed the mixing-controlled and local phase equilibrium characteristics of liquid vaporization in high injection pressure diesel engine sprays. However, most computational fluid dynamics models for engine simulations spend much effort in solving for non-equilibrium spray processes. In this study, an equilibrium phase spray model is explored. The model is developed based on jet theory and a phase equilibrium assumption, without modeling drop breakup, collision and finite-rate interfacial vaporization processes. The proposed equilibrium phase spray model is validated extensively against experimental data in simulations of the engine combustion network Spray A and in an optical diesel engine. Predictions of liquid/vapor penetration, fuel mass fraction distribution, heat release rate and emission formation are all in good agreement with experimental data. In addition, good computational efficiency and grid-independency are also seen with the present equilibrium phase model. The examined operating conditions cover wide ranges that are relevant to internal combustion engines, which include ambient temperatures from 700 to 1400 K, ambient densities from 7.6 to 22.8 kg/m3 and injection pressures from 1200 to 1500 bar for diesel sprays.
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Mudawar, I., and K. A. Estes. "Optimizing and Predicting CHF in Spray Cooling of a Square Surface." Journal of Heat Transfer 118, no. 3 (August 1, 1996): 672–79. http://dx.doi.org/10.1115/1.2822685.
Повний текст джерелаАнотація:
Spray cooling of a hot surface was investigated to ascertain the effect of nozzle-to-surface distance on critical heat flux (CHF). Full cone sprays of Fluorinert FC-72 and FC-87 were used to cool a 12.7 × 12.7 mm2 surface. A theoretical model was constructed that accurately predicts the spray’s volumetric flux (liquid volume per unit area per unit time) distribution across the heater surface. Several experimental spray sampling techniques were devised to validate this model. The impact of volumetric flux distribution on CHF was investigated experimentally. By measuring CHF for the same nozzle flow rate at different nozzle-to-surface distances, it was determined CHF can be maximized when the spray is configured such that the spray impact area just inscribes the square surface of the heater. Using this optimum configuration, CHF data were measured over broad ranges of flow rate and subcooling, resulting in a new correlation for spray cooling of small surfaces.
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Shriram Sathishkumar, Bommisetty Sambasiva Rao, Sidharth Pradeep, Solai Sairam R. M., Balaji Kalaiarasu, and Prabhu Selvaraj. "Modelling and Validating the Spray Characteristics of a Co-axial Twin-Fluid Atomizer Using OpenFOAM." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 91, no. 1 (January 17, 2022): 35–45. http://dx.doi.org/10.37934/arfmts.91.1.3545.
Повний текст джерелаАнотація:
Today, the applications of sprays cover a wide range of fields. Their role in internal combustion engines is instrumental in maintaining higher engine efficiency. A deeper understanding of the liquid-gas phase interaction in sprays is crucial to the atomization process. The methods and models used in the simulations have their challenges due to the various discretization schemes and solutions used. To develop and validate the computational models, well defined experimental data is required. In the present work, spray characteristics were studied numerically through OpenFOAM. As the spray characteristics are closely linked with the liquid breakup length, this study focuses on the primary breakup phenomena and the breakup length of the liquid jet emanating from the twin-fluid co-axial flow atomizer. Numerical simulations were performed for a wide range of initial conditions and the breakup length of the spray was validated against the experimental observed by Sivadas et al., [26]. These simulations were carried out using a Eulerian based VOF solver that models the fluid as a continuum. K-Epsilon model was used to predict the turbulent nature of the spray. The air and water velocities were varied between 19.0 to 31.3 m/s and 0.7 to 1.8 m/s respectively. The proposed model was able to predict the computed breakup length within 20% of the experimental values. The present model can be further extended to test for a co-axial swirl injector to predict finer spray formation.
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Manin, Julien, Michele Bardi, Lyle M. Pickett, and Julien Manin. "SP2-4 Evaluation of the liquid length via diffused back-illumination imaging in vaporizing diesel sprays(SP: Spray and Spray Combustion,General Session Papers)." Proceedings of the International symposium on diagnostics and modeling of combustion in internal combustion engines 2012.8 (2012): 665–73. http://dx.doi.org/10.1299/jmsesdm.2012.8.665.
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KANKKUNEN, ARI, SANTERI KOIVISTO, KARI SAARI, MIKA JARVINEN, JAMES BIGGS, and ANDREW JONES. "Experiments and visualization of sprays from beer can and turbo liquor nozzles." February 2022 21, no. 2 (March 1, 2022): 95–106. http://dx.doi.org/10.32964/tj21.2.95.
Повний текст джерелаАнотація:
Industrial scale swirl-type black liquor nozzles were studied using water as the test fluid. Simple water spraying experiments were found to be very beneficial for studying and comparing nozzles for black liquor spraying. These kinds of experiments are important for finding better nozzle designs. Three nozzle designs were investigated to understand the functional differences between these nozzles. The pres-sure loss of nozzle 1 (“tangential swirl”) and nozzle 3 (“turbo”) were 97% and 38% higher compared to nozzle 2 (“tan-gential swirl”). Spray opening angles were 75°, 60°, and 35° for nozzles 1, 2, and 3, respectively. Video imaging showed that the nozzles produced sprays that were inclined a few degrees from the nozzle centerline. Spray patter-nation showed all the sprays to be asymmetric, while nozzle 2 was the most symmetric. Laser-Doppler measure-ments showed large differences in spray velocities between nozzles. The spray velocity for nozzle 1 increased from 9 m/s to 15 m/s when the flow rate was increased from 1.5 L/s to 2.5 L/s. The resulting velocity increase for nozzle 2 was from 7 m/s to 11 m/s, and for nozzle 3, it was from 8 m/s to 13 m/s. Tangential flow (swirl) directed the spray 6°–12° away from the vertical plane. Liquid sheet breakup mechanisms and lengths were estimated by analyzing high speed video images. The liquid sheet breakup mechanism for nozzle 1 was estimated to be wave formation, and the sheet length was estimated to be about 10 cm. Sheet breakup mechanisms for nozzle 2 were wave formation and sheet perforation, and the sheet length was about 20 cm. Nozzle 3 was not supposed to form a liquid sheet. Nozzle geometry was found to greatly affect spray characteristics.
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Sparacino, Berni, d’Adamo, Krastev, Cavicchi, and Postrioti. "Impact of the Primary Break-Up Strategy on the Morphology of GDI Sprays in 3D-CFD Simulations of Multi-Hole Injectors." Energies 12, no. 15 (July 26, 2019): 2890. http://dx.doi.org/10.3390/en12152890.
Повний текст джерелаАнотація:
The scientific literature focusing on the numerical simulation of fuel sprays is rich in atomization and secondary break-up models. However, it is well known that the predictive capability of even the most diffused models is affected by the combination of injection parameters and operating conditions, especially backpressure. In this paper, an alternative atomization strategy is proposed for the 3D-Computational Fluid Dynamics (CFD) simulation of Gasoline Direct Injection (GDI) sprays, aiming at extending simulation predictive capabilities over a wider range of operating conditions. In particular, attention is focused on the effects of back pressure, which has a remarkable impact on both the morphology and the sizing of GDI sprays. 3D-CFD Lagrangian simulations of two different multi-hole injectors are presented. The first injector is a 5-hole GDI prototype unit operated at ambient conditions. The second one is the well-known Spray G, characterized by a higher back pressure (up to 0.6 MPa). Numerical results are compared against experiments in terms of liquid penetration and Phase Doppler Anemometry (PDA) data of droplet sizing/velocity and imaging. CFD results are demonstrated to be highly sensitive to spray vessel pressure, mainly because of the atomization strategy. The proposed alternative approach proves to strongly reduce such dependency. Moreover, in order to further validate the alternative primary break-up strategy adopted for the initialization of the droplets, an internal nozzle flow simulation is carried out on the Spray G injector, able to provide information on the characteristic diameter of the liquid column exiting from the nozzle.
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Sankar, S. V., D. M. Robart, and William Bachalo. "Characterization of Liquid-Liquid Mixing in Sprays Using Rainbow Refractometry." International Journal of Fluid Mechanics Research 24, no. 4-6 (1997): 665–73. http://dx.doi.org/10.1615/interjfluidmechres.v24.i4-6.220.
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Si, Xiuhua April, Muhammad Sami, and Jinxiang Xi. "Liquid Film Translocation Significantly Enhances Nasal Spray Delivery to Olfactory Region: A Numerical Simulation Study." Pharmaceutics 13, no. 6 (June 18, 2021): 903. http://dx.doi.org/10.3390/pharmaceutics13060903.
Повний текст джерелаАнотація:
Previous in vivo and ex vivo studies have tested nasal sprays with varying head positions to enhance the olfactory delivery; however, such studies often suffered from a lack of quantitative dosimetry in the target region, which relied on the observer’s subjective perception of color changes in the endoscopy images. The objective of this study is to test the feasibility of gravitationally driven droplet translocation numerically to enhance the nasal spray dosages in the olfactory region and quantify the intranasal dose distribution in the regions of interest. A computational nasal spray testing platform was developed that included a nasal spray releasing model, an airflow-droplet transport model, and an Eulerian wall film formation/translocation model. The effects of both device-related and administration-related variables on the initial olfactory deposition were studied, including droplet size, velocity, plume angle, spray release position, and orientation. The liquid film formation and translocation after nasal spray applications were simulated for both a standard and a newly proposed delivery system. Results show that the initial droplet deposition in the olfactory region is highly sensitive to the spray plume angle. For the given nasal cavity with a vertex-to-floor head position, a plume angle of 10° with a device orientation of 45° to the nostril delivered the optimal dose to the olfactory region. Liquid wall film translocation enhanced the olfactory dosage by ninefold, compared to the initial olfactory dose, for both the baseline and optimized delivery systems. The optimized delivery system delivered 6.2% of applied sprays to the olfactory region and significantly reduced drug losses in the vestibule. Rheological properties of spray formulations can be explored to harness further the benefits of liquid film translocation in targeted intranasal deliveries.
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Kooij, S. A., A. M. Moqaddam, T. C. de Goede, D. Derome, J. Carmeliet, N. Shahidzadeh, and D. Bonn. "Sprays from droplets impacting a mesh." Journal of Fluid Mechanics 871 (May 22, 2019): 489–509. http://dx.doi.org/10.1017/jfm.2019.289.
Повний текст джерелаАнотація:
In liquid spray applications, the sprays are often created by the formation and destabilization of a liquid sheet or jet. The disadvantage of such atomization processes is that the breakup is often highly irregular, causing a broad distribution of droplet sizes. As these sizes are controlled by the ligament corrugation and size, a monodisperse spray should consist of ligaments that are both smooth and of equal size. A straightforward way of creating smooth and equally sized ligaments is by droplet impact on a mesh. In this work we show that this approach does however not produce monodisperse droplets, but instead the droplet size distribution is very broad, with a large number of small satellite drops. We demonstrate that the fragmentation is controlled by a jet instability, where initial perturbations caused by the injection process result in long-wavelength disturbances that determine the final ligament breakup. During destabilization the crests of these disturbances are connected by thin ligaments which are the leading cause of the large number of small droplets. A secondary coalescence process, due to small relative velocities between droplets, partly masks this effect by reducing the amount of small droplets. Of the many parameters in this system, we describe the effect of varying the mesh size, mesh rigidity, impact velocity and wetting properties, keeping the liquid properties the same by focusing on water droplets only. We further perform lattice Boltzmann modelling of the impact process that reproduces key features seen in the experimental data.
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Somasundaram, Sivanand, and A. A. O. Tay. "A study of intermittent liquid nitrogen sprays." Applied Thermal Engineering 69, no. 1-2 (August 2014): 199–207. http://dx.doi.org/10.1016/j.applthermaleng.2013.11.066.
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Balasubramanyam, M. S., C. P. Chen, and H. P. Trinh. "A New Finite-Conductivity Droplet Evaporation Model Including Liquid Turbulence Effect." Journal of Heat Transfer 129, no. 8 (December 7, 2006): 1082–86. http://dx.doi.org/10.1115/1.2737481.
Повний текст джерелаАнотація:
A new approach to account for finite thermal conductivity and turbulence effects within atomizing droplets of an evaporating spray is presented in this paper. The model is an extension of the T-blob and T-TAB atomization/spray model of Trinh and Chen [Atomization and Sprays, 16(6), pp. 907–932]. This finite conductivity model is based on the two-temperature film theory in which the turbulence characteristics of the droplet are used to estimate the effective thermal diffusivity for the liquid-side film thickness. Both one-way and two-way coupled calculations were performed to investigate the performance of this model against the published experimental data.
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Martinez, Gabrielle L., Farzad Poursadegh, Gina M. Magnotti, Katarzyna E. Matusik, Daniel J. Duke, Benjamin W. Knox, Alan L. Kastengren, Christopher F. Powell, and Caroline L. Genzale. "Measurement of Sauter mean diameter in diesel sprays using a scattering–absorption measurement ratio technique." International Journal of Engine Research 20, no. 1 (December 19, 2018): 6–17. http://dx.doi.org/10.1177/1468087418819912.
Повний текст джерелаАнотація:
A new diagnostic for the quantification of Sauter mean diameter in high-pressure fuel sprays has been recently developed using combined optical and X-ray measurements at the Georgia Institute of Technology and Argonne National Laboratory, respectively. This diagnostic utilizes liquid scattering extinction measurements from diffuse back-illumination imaging, conducted at Georgia Tech, and liquid absorption measurements from X-ray radiography, conducted at Argonne’s Advanced Photon Source. The new diagnostic, entitled the scattering–absorption measurement ratio, quantifies two-dimensional distributions of path-integrated Sauter mean diameter, enabling the construction of the spatial history of drop size development within practical fuel sprays. This technique offers unique benefits over conventional drop-sizing methods in that it can be more robust in optically dense regions of the spray, while also providing high spatial resolution of the corresponding droplet field. The methodology for quantification of Sauter mean diameter distributions using the scattering–absorption measurement ratio technique has been previously introduced and demonstrated in diesel sprays using the Engine Combustion Network Spray D injector; however, a more detailed treatment of measurement uncertainties has been needed. In this work, we present a summary of the various sources of measurement uncertainty in the scattering–absorption measurement ratio diagnostic, like those due to the experimental setup, data processing methods, and theoretical assumptions, and assess how these sources of uncertainty affect the quantified Sauter mean diameter. The spatially resolved Sauter mean diameter measurements that result from the scattering–absorption measurement ratio diagnostic will be especially valuable to the engine modeling community for the quantitative validation of spray submodels in engine computational fluid dynamics codes. Careful evaluation and quantification of measurement uncertainties are important to support accurate model validation and to ensure the development of more predictive spray models.
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Keser, Robert, Michele Battistoni, Hong G. Im, and Hrvoje Jasak. "A Eulerian Multi-Fluid Model for High-Speed Evaporating Sprays." Processes 9, no. 6 (May 26, 2021): 941. http://dx.doi.org/10.3390/pr9060941.
Повний текст джерелаАнотація:
Advancements in internal combustion technology, such as efficiency improvements and the usage of new complex fuels, are often coupled with developments of suitable numerical tools for predicting the complex dynamic behavior of sprays. Therefore, this work presents a Eulerian multi-fluid model specialized for the dynamic behavior of dense evaporating liquid fuel sprays. The introduced model was implemented within the open-source OpenFOAM library, which is constantly gaining popularity in both industrial and academic settings. Therefore, it represents an ideal framework for such development. The presented model employs the classes method and advanced interfacial momentum transfer models. The droplet breakup is considered using the enhanced WAVE breakup model, where the mass taken from the parent droplets is distributed among child classes using a triangular distribution. Furthermore, the complex thermal behavior within the moving droplets is considered using a parabolic temperature profile and an effective thermal conductivity approach. This work includes an uncertainty estimation analysis (for both spatial and temporal resolutions) for the developed solver. Furthermore, the solver was validated against two ECN Spray A conditions (evaporating and non-evaporating). Overall, the presented results show the capability of the implemented model to successfully predict the complex dynamic behavior of dense liquid sprays for the selected operating conditions.
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Iyer, Venkatraman, and John Abraham. "An Evaluation of a Two-Fluid Eulerian-Liquid Eulerian-Gas Model for Diesel Sprays." Journal of Fluids Engineering 125, no. 4 (July 1, 2003): 660–69. http://dx.doi.org/10.1115/1.1593708.
Повний текст джерелаАнотація:
A two fluid Eulerian-liquid Eulerian-gas (ELEG) model for diesel sprays is developed. It is employed to carry out computations for diesel sprays under a wide range of ambient and injection conditions. Computed and measured results are compared to assess the accuracy of the model in the far field, i.e., at axial distances greater than 300 orifice diameters, and in the near field, i.e., at axial distances less than 100 orifice diameters. In the far field, the comparisons are of drop mean velocities and drop fluctuation velocities and in the near field they are of entrainment velocities and entrainment constants. Adequate agreement is obtained quantitatively, within 30 percent, and qualitatively as parameters are changed. Unlike in traditional Lagrangian-drop Eulerian-fluid (LDEF) approaches that are employed for diesel spray computations, adequate resolution can be employed in the near field to achieve numerical grid independence when the two-fluid model is employed. A major source of uncertainty in the near field is in the modeling of liquid jet breakup and atomization.
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Fabbri, Matteo, Shanjuan Jiang, and Vijay K. Dhir. "A Comparative Study of Cooling of High Power Density Electronics Using Sprays and Microjets." Journal of Heat Transfer 127, no. 1 (January 1, 2005): 38–48. http://dx.doi.org/10.1115/1.1804205.
Повний текст джерелаАнотація:
Direct cooling by means of jets and sprays has been considered as a solution to the problem of cooling of high power density electronic devices. Although both methods are capable of very high heat removal rates no criterion exists that helps one decide as to which one is preferable, when designing a cooling system for electronic applications. In this work, the results of an investigation of the performances of sprays and arrays of micro jets are reported. Experiments have been conducted using HAGO nozzles and orifice plates to create droplet sprays and arrays of micro jets, respectively. The liquid jets had diameters ranging from 69 to 250 μm and the pitches between the jets were 1, 2, and 3 mm. The test fluid was deionized water and the jet Reynolds number ranged between 43 and 3813. A comparison of heat transfer and pressure drop results obtained employing both sprays and jets has been carried out. The microjet arrays proved superior to the sprays since they required less pumping power per unit of power removed. A cooling module employing impinging jets was tested. Such a module would require three primary components: an orifice plate for forming jets or a nozzle to form the spray; a container to hold the nozzle, the heat source and the cooling liquid, which also serves as a heat exchanger to the ambient; and a pump which recirculates the coolant. A fan could be used to improve the heat transfer to the ambient, and it would allow the use of a smaller container. An impinging jets cooling module has been designed and tested. Heat fluxes as high as 300 W/cm2 at 80°C surface temperature could be removed using a system which includes a 4×6 array of microjets of water of 140 μm diameter impinging on a diode 5.0×8.7 mm2.
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Yin, Bifeng, Bin Xu, Hekun Jia, and Shenghao Yu. "The Effect of Elliptical Diesel Nozzles on Spray Liquid-Phase Penetration under Evaporative Conditions." Energies 13, no. 9 (May 3, 2020): 2234. http://dx.doi.org/10.3390/en13092234.
Повний текст джерелаАнотація:
Elliptical diesel nozzles affect the fuel–air mixing process, and thus combustion and exhaust emissions. Experiments were conducted to study biodiesel spray liquid-phase behaviors for elliptical and circular nozzles through the Mie-scattering method under evaporative conditions. Based on the measurements, the results show that the elliptical nozzle spray liquid-phase penetration is smaller than the circular one under steady-state conditions. The deformation and the axis-switching behaviors of the elliptical jet are helpful in accelerating the breakup of the liquid core. Moreover, the injection pressure has little impact on the penetration of the liquid-phase spray for either geometrical orifice. Additionally, increasing the ambient temperature can reduce the penetration of liquid-phase spray, because an increase in temperature increases the rate of evaporation. The differences in steady liquid-phase penetration between circular and elliptical sprays decrease as the ambient temperature increases. Additionally, increasing the backpressure can decrease the liquid-phase penetration. The differences in steady liquid-phase penetration between circular and elliptical nozzles are reduced with the increase in backpressure, probably due to the axis-switching and deformation behaviors of the elliptical jet being restrained under high-backpressure conditions. Finally, the application of an elliptical orifice is beneficial for decreasing the spray liquid-phase penetration, and thus avoiding the fuel impingement in small engine combustion chambers. The lower liquid-phase penetration for elliptical spray indicated higher fuel and air mixture quality, which is helpful for reducing the diesel engine exhaust soot emissions.
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Mzad, Hocine, Abdessalam Otmani, Kamel Bey, and Stanisław Łopata. "A model of water-spray cooling effect on a continuous casting process." MATEC Web of Conferences 240 (2018): 05022. http://dx.doi.org/10.1051/matecconf/201824005022.
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The intention of this study is to give an idea about the influence of water-spray cooling on the solidification process of the liquid metal which enables to locate the shear region. The effect of spray heat transfer coefficient (hspray) during the liquid-to-solid transition through the cooled zone temperature and the metal latent heat of solidification are highlighted. A gray iron continuous casting process subjected to water-sprays cooling was simulated using the commercial code COMSOL MULTIPHYSICS 5.2. The obtained results show the great influence of hspray on the location of transition region as well as the relationship between hspray, wall outer temperature, latent heat dissipation, and the solidification time.
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Estes, Kurt A., and Issam Mudawar. "Comparison of Two-Phase Electronic Cooling Using Free Jets and Sprays." Journal of Electronic Packaging 117, no. 4 (December 1, 1995): 323–32. http://dx.doi.org/10.1115/1.2792112.
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The performances of free jets and sprays were compared experimentally in cooling a 12.7 × 12.7 mm2 chip in order to ascertain the effects of key parameters on cooling performance and to develop correlations for critical heat flux (CHF) which are applicable to dielectric coolants. Increasing liquid flow rate and subcooling increased CHF for both cooling schemes. At high subcooling, comparable CHF values were attained with both for equal flow rates. However, spray cooling produced much greater CHF at low subcooling than did jet cooling. This phenomenon was found to be closely related to the hydrodynamic structure of the liquid film deposited upon the chip surface. In jet cooling, the film (wall jet), being anchored to the surface only at the impingement zone, was separated from the surface during vigorous boiling due to the momentum of vapor normal to the surface. The individual spray drops were more effective at securing liquid film contact with the surface at low subcooling, which delayed CHF relative to jet cooling with the same flow rate. This paper also discusses practical concerns associated with implementation of each cooling scheme including system reliability and the risk associated with premature CHF during chip power transients.
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Naz, Muhammad Yasin, Shaharin Anwar Sulaiman, and Bambang Ari-Wahjoedi. "Experimental Study of Airless Spray Jet Breakup at Elevated Temperature and Pressure." Applied Mechanics and Materials 393 (September 2013): 711–16. http://dx.doi.org/10.4028/www.scientific.net/amm.393.711.
Повний текст джерелаАнотація:
The presented research work was focused onto the understanding of the jet behavior of the sprays of heated water during the low pressure atomization process. This task was accomplished using an in-house built intermittently forced liquid spraying system capable of lowering the liquid viscosity and surface tension to a desired value and then atomizing it into a full cone spray patterns in the ambient air surrounding. Using a high speed camera, the jet breakup dynamics were visualized as a function of system input parameters. The analysis of the grabbed images confirmed the strong influence of these processing parameters on full cone spray characteristics. It was also predicted that heated liquids generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium that is the induction of thermal energy enhances the jet disintegration ability. The spray cone width and angle did not vary significantly whereas the Weber and Reynolds numbers along with other nozzle flow parameters showed an appreciable response to the load pressure and temperature at early stages of water injection. The ultimate objective of the work was to understand and control the airless spray jet breakup mechanism under reduced load pressure and high water temperature.
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Smakulski, Przemysław. "Method of high heat flux removal by usage of liquid spray cooling." Archives of Thermodynamics 34, no. 3 (September 1, 2013): 173–84. http://dx.doi.org/10.2478/aoter-2013-0023.
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Abstract High heat flux removal are important issue in many perspective applications such as computer chips, laser diode arrays, or boilers working on supercritical parameters. Electronic microchips constructed nowadays are model example of high heat flux removal, where the cooling system have to maintain the temperature below 358 K and take heat flux up to 300 W/cm2. One of the most efficient methods of microchips cooling turns out to be the spray cooling method. Review of installations has been accomplished for removal at high heat flux with liquid sprays. In the article are shown high flux removal characteristic and dependences, boiling critical parameters, as also the numerical method of spray cooling analysis.
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Asgari, Behrad, and Ehsan Amani. "An improved spray-wall interaction model for Eulerian-Lagrangian simulation of liquid sprays." International Journal of Multiphase Flow 134 (January 2021): 103487. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2020.103487.
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Figueiredo, Miguel, Guido Marseglia, Ana S. Moita, Miguel R. O. Panão, Ana P. C. Ribeiro, Carlo M. Medaglia, and António L. N. Moreira. "Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography." Energies 13, no. 22 (November 10, 2020): 5864. http://dx.doi.org/10.3390/en13225864.
Повний текст джерелаАнотація:
Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given to the use of nanofluids in sprays due to their potential to enhance the heat transfer mechanisms. The results for low nanoparticle concentrations (up to 1 wt.%) show that the surfactant added to water, required to stabilize the nanofluids and minimize particle clustering, affects the spray’s main characteristics. Namely, the surfactant decreases the liquid surface tension leading to a larger wetted area and wettability, promoting heat transfer between the surface and the liquid film. However, since lower surface tension also tends to enhance splash near the edges of the wetted area, the gold nanospheres act to lessen such disturbances due to an increase of the solutions’ viscosity, thus increasing the heat flux removed from the spray slightly. The experimental results obtained from this work demonstrate that the maximum heat convection coefficients evaluated for the nanofluids can be 9.8% to 21.9% higher than those obtained with the base fluid and 11.5% to 38.8% higher when compared with those obtained with DI water.
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MATHIAUD, JULIEN. "LOCAL SMOOTH SOLUTIONS OF A THIN SPRAY MODEL WITH COLLISIONS." Mathematical Models and Methods in Applied Sciences 20, no. 02 (February 2010): 191–221. http://dx.doi.org/10.1142/s0218202510004192.
Повний текст джерелаАнотація:
Sprays are complex flows made of liquid droplets surrounded by a gas. The aim of this paper is to study the local in time well-posedness of a collisional thin spray model, that is a coupling between Euler equations for a perfect gas and a Vlasov–Boltzmann equation for the droplets. We prove the existence and uniqueness of (local in time) solutions for this problem as soon as initial data are smooth enough.
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Grobuschek, Nina, Oliver Lecnik, Martin Schmid, and Gerald Gubitz. "Mass uniformity of nasal sprays." Scientia Pharmaceutica 71, no. 3 (June 28, 2003): 151–64. http://dx.doi.org/10.3797/scipharm.aut-03-16.
Повний текст джерелаАнотація:
The uniformity of nasal spray dose delivery was investigated. Four selected nasal sprays commercially available on the European market were checked for their mass uniformity according to the guidelines of the European Pharmacopoeia and recent draft guidelines of the Food and Drug Administration (FDA). Mass uniformity was also determined with simulation of a patient's use daily, and at 3- and 7- day intervals. The influence of the degree of filling and different storage positions on mass uniformity were also investigated. At first usage, all preparations fulfilled the specifications of the Ph.Eur. and the FDA draft guidelines. When patient application was simulated, however, the dose accuracy decreased significantly with some of the preparations with increasing time of non-usage, presumably due to evaporation of liquid in the application system. This is indicated by a loss of weight of the nasal spray flasks observed during simulated weekly usage. Under these conditions (6 days' storage without use, same demands for uniformity of mass of the delivered dose), one of the preparations even failed to meet the Ph.Eur. and FDA limits.
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Pickett, Lyle M., Sanghoon Kook, and Timothy C. Williams. "Transient Liquid Penetration of Early-Injection Diesel Sprays." SAE International Journal of Engines 2, no. 1 (April 20, 2009): 785–804. http://dx.doi.org/10.4271/2009-01-0839.
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Tseng, Ampere A., Miroslav Raudensky, and Tae-Woo Lee. "Liquid Sprays for Heat Transfer Enhancements: A Review." Heat Transfer Engineering 37, no. 16 (May 4, 2016): 1401–17. http://dx.doi.org/10.1080/01457632.2015.1136168.
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Ghaffar, Zulkifli Abdul, Ahmad Hussein Abdul Hamid, and Mohd Syazwan Firdaus Mat Rashid. "Spray Characteristics of Swirl Effervescent Injector in Rocket Application: A Review." Applied Mechanics and Materials 225 (November 2012): 423–28. http://dx.doi.org/10.4028/www.scientific.net/amm.225.423.
Повний текст джерелаАнотація:
Injector is one of the vital devices in liquid rocket engine (LRE) as small changes in its configurations and design can result in significantly different LRE performance. Characteristics of spray such as spray cone angle, breakup length and Sauter mean diameter (SMD) are examples of crucial parameters that play the important role in the performance of liquid propellant rocket engine. Wider spray cone angle is beneficial for widespread of fuel in the combustion chamber for fast quiet ignition and a shorter breakup length provides shorter combustion chamber to be utilized and small SMD will result in fast and clean combustion. There are several mechanisms of liquid atomization such as swirling, e.g. jet swirl atomization or introducing bubbles into the liquid and effervescent atomization. Introducing a swirl component in the flow can enhance the propellant atomization and mixing whereas introducing bubbling gas directly into the liquid stream inside the injector leads to finer sprays even at lower injection pressures. This paper reviews the influence of both operating conditions and injector internal geometries towards the spray characteristics of swirl effervescent injectors. Operating conditions reviewed are injection pressure and gas-to-liquid ratio (GLR), while the injector internal geometries reviewed are limited to swirler geometry, mixing chamber diameter (dc), mixing chamber length (lc), aeration hole diameter (da), discharge orifice diameter (do) and discharge orifice length (lo).