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Artigos de revistas sobre o assunto "Sea spray generation"
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Smith, M. H., e N. M. Harrison. "The sea spray generation function". Journal of Aerosol Science 29 (setembro de 1998): S189—S190. http://dx.doi.org/10.1016/s0021-8502(98)00280-8.
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Andreas, Edgar L. "Sea Spray Generation at a Rocky Shoreline". Journal of Applied Meteorology and Climatology 55, n.º 9 (setembro de 2016): 2037–52. http://dx.doi.org/10.1175/jamc-d-15-0211.1.
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AbstractWith sea ice in the Arctic continuing to shrink, the Arctic Ocean and the surrounding marginal seas will become more like the ocean at lower latitudes. In particular, with more open water, air–sea exchange will be more intense and storms will be stronger and more frequent. The longer fetches over open water and the more energetic storms will combine to produce higher waves and more sea spray. Offshore structures—such as oil drilling, exploration, and production platforms—will face increased hazards from freezing sea spray. On the basis of sea spray observations made with a cloud-imaging probe at Mount Desert Rock (an island off the coast of Maine), the spray that artificial islands built in the Arctic might experience is quantified. Mount Desert Rock is small, low, and unvegetated and has an abrupt, rocky shoreline like these artificial islands might have. Many of the observations were at air temperatures below freezing. This paper reports the near-surface spray concentration and the rate of spray production at this rocky shoreline for spray droplets with radii from 6.25 to 143.75 μm and for wind speeds from 5 to 17 m s−1. Spray concentration increases as the cube of the wind speed, but the shape of the concentration spectrum with respect to radius does not change with wind speed. Both near-surface spray concentration and the spray-production rate are three orders of magnitude higher at this rocky shoreline than over the open ocean because of the high energy and resulting continuous white water in the surf zone.
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Ortiz-Suslow, David G., Brian K. Haus, Sanchit Mehta e Nathan J. M. Laxague. "Sea Spray Generation in Very High Winds". Journal of the Atmospheric Sciences 73, n.º 10 (21 de setembro de 2016): 3975–95. http://dx.doi.org/10.1175/jas-d-15-0249.1.
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Abstract Quantifying the amount and rate of sea spray production at the ocean surface is critical to understanding the effect spray has on atmospheric boundary layer processes (e.g., tropical cyclones). Currently, only limited observational data exist that can be used to validate available droplet production models. To help fill this gap, a laboratory experiment was conducted that directly observed the vertical distribution of spume droplets above actively breaking waves. The experiments were carried out in hurricane-force conditions (10-m equivalent wind speed of 36–54 m s−1), and the observed particles ranged in radius r from 80 to nearly 1400 μm. High-resolution profiles (3 mm) were reconstructed from optical imagery taken within the boundary layer, ranging from 2 to 6 times the local significant wave height. Number concentrations were observed to have a radius dependence proportional to r−3 leading to spume production estimates that diverge from typical source models, which tend to exhibit a radius falloff closer to r−8. This was particularly significant for droplets with radii circa 1 mm whose modeled production rates were several orders of magnitude less than the rates expected from the observed concentrations. The vertical dependence of the number concentrations was observed to follow a logarithmic profile, which does not confirm the power-law relationship expected by a conventional spume generation parameterization. These observations bear significant implications for efforts to characterize the role these large droplets play in boundary layer processes under high-wind conditions.
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Mueller, James A., e Fabrice Veron. "A Sea State–Dependent Spume Generation Function". Journal of Physical Oceanography 39, n.º 9 (1 de setembro de 2009): 2363–72. http://dx.doi.org/10.1175/2009jpo4113.1.
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Abstract The uncertainty of the sea spray generation function continues to obscure spray-mediated momentum and scalar fluxes, especially for intense wind conditions. Most previous studies assume a constant form (spectral shape) for the droplet distribution, even though a shift to smaller drops with increased wind forcing is expected. In this paper, a new generation function for spume drops is derived, but unlike previous studies, both its form and magnitude change with wind forcing. Fairly good agreement is found between this spume generation function and the limited data available. A potential explanation for the vast size differences among previous spume generation studies is also provided by distinguishing the drops formed at the surface from the drops transported vertically where measurements are routinely made.
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Mueller, James A., e Fabrice Veron. "Impact of Sea Spray on Air–Sea Fluxes. Part II: Feedback Effects". Journal of Physical Oceanography 44, n.º 11 (1 de novembro de 2014): 2835–53. http://dx.doi.org/10.1175/jpo-d-13-0246.1.
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Abstract This paper presents estimations for the transfer of momentum, heat, and water mass between the air and the sea. The results from Lagrangian stochastic simulations of sea spray drops (see Part I), along with two sea spray generation functions, are used to calculate the spray-mediated flux components of the air–sea fluxes. When the spray-mediated fluxes constitute a significant fraction of the total fluxes under certain conditions, their feedback effect on the atmosphere cannot be neglected. The authors derive a simplified feedback model to investigate such cases, finding that the spray-mediated fluxes may be especially sensitive to the size distribution of the drops. The total effective air–sea fluxes lead to drag and enthalpy coefficients that increase modestly with wind speed. The rate of increase for the drag coefficient is greatest at moderate wind speeds, while the rate of increase for the enthalpy coefficient is greatest at higher wind speeds where the spray is ubiquitous.
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Garg, Nikhil, Eddie Yin Kwee Ng e Srikanth Narasimalu. "The effects of sea spray and atmosphere–wave coupling on air–sea exchange during a tropical cyclone". Atmospheric Chemistry and Physics 18, n.º 8 (27 de abril de 2018): 6001–21. http://dx.doi.org/10.5194/acp-18-6001-2018.
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Abstract. The study investigates the role of the air–sea interface using numerical simulations of Hurricane Arthur (2014) in the Atlantic. More specifically, the present study aims to discern the role ocean surface waves and sea spray play in modulating the intensity and structure of a tropical cyclone (TC). To investigate the effects of ocean surface waves and sea spray, numerical simulations were carried out using a coupled atmosphere–wave model, whereby a sea spray microphysical model was incorporated within the coupled model. Furthermore, this study also explores how sea spray generation can be modelled using wave energy dissipation due to whitecaps; whitecaps are considered as the primary mode of spray droplets generation at hurricane intensity wind speeds. Three different numerical simulations including the sea- state-dependent momentum flux, the sea-spray-mediated heat flux, and a combination of the former two processes with the sea-spray-mediated momentum flux were conducted. The foregoing numerical simulations were evaluated against the National Data Buoy Center (NDBC) buoy and satellite altimeter measurements as well as a control simulation using an uncoupled atmosphere model. The results indicate that the model simulations were able to capture the storm track and intensity: the surface wave coupling results in a stronger TC. Moreover, it is also noted that when only spray-mediated heat fluxes are applied in conjunction with the sea-state-dependent momentum flux, they result in a slightly weaker TC, albeit stronger compared to the control simulation. However, when a spray-mediated momentum flux is applied together with spray heat fluxes, it results in a comparably stronger TC. The results presented here allude to the role surface friction plays in the intensification of a TC.
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Wan, Zhanhong, Luping Li, Zhigen Wu, Jiawang Chen e Xiuyang Lü. "The impact of ocean waves on spray stress and surface drag coefficient". International Journal of Numerical Methods for Heat & Fluid Flow 29, n.º 2 (4 de fevereiro de 2019): 523–35. http://dx.doi.org/10.1108/hff-05-2018-0237.
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Purpose The behaviors of sea surface drag coefficient should be well understood for an accurate hurricane prediction. The speed of wind has been applied to characterize the spray production; however, this could result in inaccurate spray productions compared to the experimental or field data if the influence of wave state is not considered. This paper aims to integrate a new sea spray generation function, described by windsea Reynolds number, into the spray momentum flux formula to calculate the spray momentum. Design/methodology/approach On the basis of this spray momentum, this study proposes the new formulas of spray stress and drag coefficient when the wind speed is high. Findings Results of the revised formulas show that wave status had significant effects on the spray stress and sea surface drag coefficient. Also, wave age was found to be an important parameter that affects the drag coefficient. The drag coefficient decreased with the increasing wave age. Comparison between this study’s theoretical and observation values of drag coefficient shows that the study results are close to the measured values. Research limitations/implications The research findings can enhance the understanding of the behaviors of sea surface drag for an accurate hurricane prediction. Originality/value A new sea spray generation function, described by windsea Reynolds number, is integrated into the spray momentum flux formula to calculate the spray momentum. On the basis of this spray momentum, this study proposes the new formulas of spray stress and drag coefficient when the wind speed is high.
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Bao, J. W., C. W. Fairall, S. A. Michelson e L. Bianco. "Parameterizations of Sea-Spray Impact on the Air–Sea Momentum and Heat Fluxes". Monthly Weather Review 139, n.º 12 (1 de dezembro de 2011): 3781–97. http://dx.doi.org/10.1175/mwr-d-11-00007.1.
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Abstract This paper focuses on parameterizing the effect of sea spray at hurricane-strength winds on the momentum and heat fluxes in weather prediction models using the Monin–Obukhov similarity theory (a common framework for the parameterizations of air–sea fluxes). In this scheme, the mass-density effect of sea spray is considered as an additional modification to the stratification of the near-surface profiles of wind, temperature, and moisture in the marine surface boundary layer (MSBL). The overall impact of sea-spray droplets on the mean profiles of wind, temperature, and moisture depends on the wind speed at the level of sea-spray generation. As the wind speed increases, the mean droplet size and the mass flux of sea-spray increase, rendering an increase of stability in the MSBL and the leveling-off of the surface drag. Sea spray also tends to increase the total air–sea sensible and latent heat fluxes at high winds. Results from sensitivity testing of the scheme in a numerical weather prediction model for an idealized case of hurricane intensification are presented along with a dynamical interpretation of the impact of the parameterized sea-spray physics on the structure of the hurricane boundary layer.
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Piazzola, J., P. Forget e S. Despiau. "A sea spray generation function for fetch-limited conditions". Annales Geophysicae 20, n.º 1 (31 de janeiro de 2002): 121–31. http://dx.doi.org/10.5194/angeo-20-121-2002.
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Abstract. This paper presents a sea spray generation function for aerosols produced by bubbles bursting that accounts for the effects of fetch. This is achieved by introducing a fetch-dependent model for the whitecap fraction, which is valid for fetch-limited conditions, i.e. steady-state conditions of the wave field in the whitecap droplet flux derived by Monahan et al. (1986). The aerosol generation fluxes calculated by this method show an enhancement of the aerosol production with increasing fetch. However, the predicted generation fluxes are lower than those calculated by using the classical model for the whitecap fraction proposed by Monahan and O’Muircheartaigh (1980). The results are then compared to aerosol size distributions measured in a Mediterranean coastal site at various fetch lengths. The data confirm the role of fetch, through its influence on marine aerosol generation and subsequent particle dispersion. The aerosol size distributions are divided into "fine" and "coarse" fractions. Submicrometer particles decrease in concentration at larger fetch, while the concentrations of super micron aerosols increase with increasing fetch.Key words. Atmospheric composition and structure (aerosols and particles) Meteorology and atmospheric dynamics (waves and ties) Oceanography: physical (air-sea interactions)
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Zhang, Ting. "The Impact of Surface Waves and Spray Injection Velocities on Air–Sea Momentum and Heat Fluxes". Atmosphere 14, n.º 10 (28 de setembro de 2023): 1500. http://dx.doi.org/10.3390/atmos14101500.
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Surface waves and sea spray play a significant role in air–sea fluxes in high winds. The present study used a marine atmosphere surface layer (MASL), which couples the traditional Monin–Obukhov similarity theory, sea spray generation function, the balance of turbulent kinetic budget, and momentum/enthalpy conservation equations. Based on this model, the effects of wave states and spray injection velocities on air–sea momentum/enthalpy fluxes and near-surface wind/temperature profiles were theoretically investigated. Based on the assumption that the velocity of injected spray is the same as that of the ambient airflow, it was found that spray could increase the near-surface air turbulence intensity and inhibit air–sea fluxes at 10 m above the sea surface. Correspondingly, near-surface wind speeds and temperature increase in high winds. This phenomenon becomes prominent in cases of large wave ages or surface waves supporting a minority of air–sea fluxes. Based on the assumption that the velocity of the edges of breaking water bags is used to estimate that of spray injection, the opposite results were found: spray could weaken the near-surface air turbulence and increase total air–sea fluxes at 10 m above the sea surface. In this case, the near-surface wind speeds and temperature decreased. This reduction becomes remarkable when surface waves are full-developed or the majority of air–sea momentum fluxes are supported by waves.
Teses / dissertações sobre o assunto "Sea spray generation"
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Adams, Ellen M. "Spectroscopic Studies of Atmospherically- and Biologically-Relevant Interfaces: Lipids, Ions, and Interfacial Water Structure". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480608026126993.
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Bruch, William. "Étude expérimentale et numérique de la génération et du transport des aérosols marins à l'interface air-mer pour des vents forts, et conséquences sur les propriétés de la couche limite atmosphérique marine". Electronic Thesis or Diss., Toulon, 2021. http://www.theses.fr/2021TOUL0002.
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Les embruns sont des aérosols en phase aqueuse générés à la surface de l’eau. Au large, ils sont générés par des mécanismes tel que le déferlement et l’écrêtage. Aujourd’hui, la connaissance portant sur les embruns excédant 20 µm de rayon reste limitée. Cette thèse vise à améliorer la compréhension des processus de génération, de transport, et les impacts sur les propriétés de la couche limite atmosphérique marine (CLAM). La campagne MATE2019 est ainsi menée à l’installation air-mer de Luminy (Marseille, France) afin d’étudier le rôle des interactions vague-vent sur la génération. Une analyse d’échelle révèle que la génération d’embruns corrèle le mieux avec la variance de pente de vagues pour les plus grosses gouttelettes ‘spume’ générées par écrêtage. Pour les plus petites gouttelettes ‘jet’ générées par éclatement de bulles, la meilleure corrélation est obtenue avec un nombre adimensionnel combinant la variance de pentes de vagues, l’age de vague, et un nombre de Reynolds adapté aux mers de vent. Il en résulte la formulation de deux fonctions de génération d’embruns dépendantes sur l’état de mer, valides pour des vents de 12–20 m s-1 et des rayons de 3–35 µm. Extrapolées aux conditions in situ, les fonctions de génération issues du laboratoire sont paramétrées dans les modèles numériques MACMod et MESO-NH, à leurs tours validés à l’aide de mesures terrain, dont une nouvelle campagne de mesure effectuée pendant la thèse dans le Golfe de Gascogne. Les meilleures performances de modélisation sont obtenues avec les fonctions de génération issues du laboratoire. Ces résultats permettent de mieux appréhender l’impact des embruns sur la CLAMSea spray droplets are aqueous phase aerosols generated from the water surface. In the open ocean, they are generated as a result of wind-forced wave breaking and surface-tearing mechanisms. To this day, knowledge of sea spray particles larger than 20 µm radius is sparse. The present thesis aims to improve knowledge of the sea spray generation flux, as well as transport and impacts on the properties of the marine atmospheric boundary layer (MABL). To this end, the effects of wind–wave interactions on the surface sea spray generation flux are investigated during the MATE2019 experiment, conducted at the large wave–wind facility in Luminy (Marseille, France). Scaling analysis shows that the sea spray generation is best correlated with the wave-slope variance for thelarger spume droplets generated by surface tearing. For the smaller jet droplets generated by bubble bursting, the highest correlation is found with a nondimensional number combining the wave-slope variance, the wave age, and a windsea Reynolds number. This resulted in the formulation of two wave-state-dependent sea spray generation functions, each valid for wind speeds 12–20 m s-1 and radii 3–35 µm. Upscaled to the field, the laboratory-derived generation functions are parameterized in the MACMod and MESO-NH numerical models, and validated using field data collected during the thesis in the Bay of Biscay for this purpose. Best model performance is found with the laboratory generation functions. Such results are encouraging for the study of sea spray impacts on the properties of the MABL
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Chang, Yun Lih, e 張雲麗. "The stability of sea-spray aerosol generation and the effects of local circulation on it". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/26514496644284814526.
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碩士國立中央大學
環境工程研究所
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This work investigated the effects of local circulation on the spread of sea-spray aerosol and the stability of its generation. Arosols from seashore and the inner-land area were collected to analyze their size distributions and the water- soluble ion contents. The proportion from each of the three parts of the composite species from water-soluble ions was further estimated in this study. The results from the field sampling of Taoyuan and Hsinchu areas showed that the modes of aerosol size spectra and the proportion of aerosol ionic species were evidently influenced by the land-sea breeze. From the calculation of enhancement factor, ionic species with sea origin could be identified. By using the scheme of "chlorine loss", the analyzed water-soluble ions were divided into three parts, i.e., sea-salt, non-sea-salt, and non-sea-salt calcium and magnesium. The percentage of sea-salt contents was found to increase with the wind speed of the sea breeze while that of the non-sea-salt compositions was increased with the decrease of the land breeze. A seashore site on the roof of a one floor building located in the Peace Island scenic area at Keelung City was chosen to sample aerosols. The results revealed that particles with the similar size spectra were characterized with the similar water-soluble ion contents. Meanwhile, by applying the enhancement factor on the collected aerosols the species originated from the sea could also be singled out.
Capítulos de livros sobre o assunto "Sea spray generation"
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Maun, M. Anwar. "Burial by sand". In The Biology of Coastal Sand Dunes. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198570356.003.0011.
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In coastal dune systems, plant communities are fundamentally the product of interaction between disturbance of the substrate, impact of high wind velocities, salt spray episodes, sand accretion levels and other factors of the environmental complex. Burial by sand is probably the most important physical stress that alters species diversity by eliminating disturbance-prone species (Maun 1998). There is a close correlation between sand movement and species composition, coverage and density (Moreno-Casasola 1986; Perumal 1994; Martínez et al. 2001). Sand accretion kills intolerant species, reduces the relative abundance of less tolerant species and increases the abundance of tolerant species. It filters out species as the level of burial starts to exceed their levels of tolerance. For example, lichens and mosses are the first to be eliminated, then the annuals and biennials and finally the herbaceous and woody perennials. Again within each life form and genus there are significant differences in survivability. Burial imposes a strong stress on production by altering normal growth conditions and exposing plants to extreme physiological limits of tolerance. Do plant communities occurring in different locations within a dune system correspond to the amount of sand deposition? Several studies (Birse et al. 1957; Moreno- Casasola 1986; Perumal 1994) show that the species composition and their distribution are strongly related to the long-term average sand deposition. The evolution of a plant community in coastal foredunes requires frequent and persistent predictable burial events specific to a particular coast. In a large majority of sea coasts burial occurrences are of relatively low magnitude and species occupying the coasts are well adapted to withstand the stress imposed by burial. This recurring event within the generation times of plant species allows them to acquire genes of resistance over time and evolution of adaptations to live in this habitat. A prerequisite to survive in this habitat happens to be the ability to withstand partial inundation by sand. To survive the dynamic substrate movement a plant species must be a perennial, be able to withstand burial, endure xerophytic environment, spread radially and vertically, and adapt to exposure on deflation and coverage on burial (Cowles 1899).
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Liu, Liang, Yuanlong Yang e Meiyi Liu. "Experimental Study on the Atomization Characteristics of an Aerosol Spray Nozzle". In Advances in Transdisciplinary Engineering. IOS Press, 2023. http://dx.doi.org/10.3233/atde230374.
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Inlet air filtration is an important part of the intake systems of the ships and coastal installations which filters out the salt aerosol particles to improve the intake air quality. Experimental systems for the inlet filter should include the salt aerosol nozzle, and the nozzle should be capable of generate various kinds of salt aerosol particles with different diameters since the sea salt aerosol possess many sizes particles in the marine environment. This paper experimentally investigates the effect of two design parameters, droplet mass flow rate and inlet pressure, on the particle diameter distribution of salt aerosol generating device. When the droplet mass flow rate increases, the research findings indicate that the particle sizes produced by the employed aerosol spray nozzle become larger. On the other hand, with the growing inlet pressure, the sizes of the sprayed particles become smaller. The results show that there are two methods to diminish the sizes of aerosol particles and improve the performance of the nozzle, one is increasing the air inlet pressure and the other is decreasing the droplet mass flow rate. And the former method gives better results than the latter method with respect to the improvement of the atomization performance.
Trabalhos de conferências sobre o assunto "Sea spray generation"
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Yamada, Fuminori, e Tokuzou Hosoyamada. "COMPREHENSIVE NUMERICAL CALCULATION METHOD OF GENERATION AND TRANSPOTATION OF SEA SALT SPRAY". In Proceedings of the 31st International Conference. World Scientific Publishing Company, 2009. http://dx.doi.org/10.1142/9789814277426_0018.
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Simmons, Benjamin M., Heena V. Panchasara e Ajay K. Agrawal. "A Comparison of Air-Blast and Flow-Blurring Injectors Using Phase Doppler Particle Analyzer Technique". In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60239.
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Recent research on biofuels for power generation has typically focused on biodiesel because the biodiesel feedstrock, e.g., vegetable oil, poses significant combustion problems related to poor atomization. Existing injectors cannot effectively atomize high viscosity fuels such as vegetable oil. However, a new, novel flow-blurring (FB) injector concept has shown promise in overcoming the atomization problems. In this study, a FB injector is compared to a commercial air-blast (AB) injector operated with water at ambient conditions of temperature and pressure. Laser sheet visualization and Phase Doppler Particle Analyzer (PDPA) systems are used to obtain the spray characteristics for a range of air to liquid (ALR) ratios. Results show significant difference in distributions of Sauter Mean Diameters (SMDs), and mean and root-mean square axial velocity for the two injectors operated at a fixed ALR. In comparison to the AB injector, the FB injector produced spray with smaller SMDs, a smaller SMD range over the spray volume, higher RMS and mean axial velocities in the center region, and a compact spray with spray angle nearly independent of ALR. Results show that the FB injector is an effective way of atomizing liquids at relatively low ALRs compared to a traditional AB injector, without the additional pressure drop penalty.
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Dhar, Sushmit, Eirik M. Samuelsen, Masoud Naseri, Karl G. Aarsæther e Kåre Edvardsen. "Spray Icing on ONEGA Vessel- A Comparison of Liquid Water Content Expressions". In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79919.
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Abstract The hazards associated with ice accretion primarily due to impinging freezing sea spray on ship structures are considered among serious safety concerns for ships operating in the colder regions. An accurate sea-spray icing-estimation model to evaluate the ice accumulation during operations in these regions can make marine operations safer. The accuracy of the present icing models for estimating icing on ships is substantially dependent on the incoming spray flux generated by the wave-ship interaction. In order to illustrate this, the vessel icing incident of the fishing vessel ONEGA is considered, which capsized after encountering heavy icing. In this study, the ONEGA vessel is modeled using a stability-calculation program. Then assuming the vessel to maintain minimum stability criteria prior to icing, the minimum likely amount of ice accumulation in the exposed locations that destabilized the vessel is estimated. This estimation is compared against another method used to evaluate ice thickness over the period ONEGA was accreting ice. The latter method utilizes the operational weather forecasting model used by MET Norway — “Marine-Icing model for the Norwegian COast Guard (MINCOG)”. The MINCOG model uses spray-flux estimations based on past empirical observations mainly obtained from fishing trawlers. The spray-flux consists of important elements like the liquid-water content (lwc) and the spray-generation frequency. An analysis is carried out applying different formulations for these two elements proposed by different researchers to see the variation in evaluating the total ice accumulation. After noticing the difference in results in total ice thickness from the stability and the icing-model methods used in this study, it is concluded that more investigation and field measurements are needed concerning the neglecting of the contribution of wind-generated spray in the spray flux formula used in MINCOG. Accordingly, multiple real-time spray measurements to develop a more suitable spray-flux formulation may improve the ice accumulation estimation over a longer time period.
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Mund, Friederike C., e Pericles Pilidis. "Effects of Spray Parameters and Operating Conditions on an Industrial Gas Turbine Washing System". In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53551.
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Gas turbines for power generation are exposed to a variety of ambient conditions and are therefore bound to breathe contaminated airflow, thus degrading the engines internal gas path. In particular, accumulated debris on the compressor blades reduces engine efficiency. To recover this performance loss, online compressor washes may be performed. Cleaning fluid is injected through the nozzles upstream of the compressor to wash off the debris from the blades. This paper presents a numerical study of a generic compressor washing system based on an application case for a heavy duty gas turbine power plant. The inlet duct of the engine was modeled and droplet trajectories were calculated. Different spray patterns including single jet and full cone have been investigated for different ranges of injection velocity and droplet size. The spray angle was evaluated experimentally and was used to model the full cone spray pattern. The boundary conditions for the airflow were iterated with a performance simulation tool to match pressure loss and mass flow. To investigate the effect of different operating conditions on the airflow and spray distribution, an installation scenario of the engine at altitude on a hot summer day was modeled. The scenario was based on a review of plant installations and local meteorological conditions. Fluid concentration plots at the compressor inlet plane were evaluated for the different computational cases. Generally with lower injection momentum, the water droplets were significantly deflected by the main airflow. Higher injection velocity and droplet size reduced the effect of the main airflow. Different operating conditions and the significant change of air mass flow affected the spray distribution of the washing system at the compressor inlet. This can be compensated by adjusting the injection angles.
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Chrigui, M., A. Sadiki e J. Janicka. "Numerical Analysis of Spray Dispersion, Evaporation and Combustion in a Single Gas Turbine Combustor". In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51253.
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Spray dispersion, evaporation and combustion have been numerically studied in a complex industrial configuration, which consists in a single annular combustor that was experimentally measured by Rolls-Royce-Deutschland Company. Simulations have been achieved using the Eulerian-Lagrangian approach. The computations of the continuous phase have been performed by means of RANS simulations. Though the k-ε as well as the Reynolds Stress model (Jones-Musonge) have been used for turbulence modeling. The 3D-computations have been performed in a fully two-way coupling. The effects of turbulence on droplets distribution are accounted for using the Markov sequence dispersion model. The equilibrium as well as the non-equilibrium evaporation model have been applied. In order to account for the combustion, the diffusion flame model is chosen. It relies on the computation of the mixture fraction that has been affected by the presence of vapor source terms. For the interaction of the turbulence with the chemistry, the mixture fraction variance has also been solved. For that purpose a presumed beta-PDF function has been considered. The equilibrium and the flamelet chemistry approaches have been used for the generation of the chemistry tables. The performed simulations have also been compared to commercial CFD-codes. From there one observes, that the obtained results using the mentioned sub-models combination agree most favorably with experimental measurements. One noted that the Reynolds Stress model provided smoother temperature distribution compared to k-ε. The flamelet model has been performed using three different scalar dissipation rates. One observes that differences are mainly located at the nozzle exit, where the scalar dissipation rate has got the highest value. Although the comparison between the numerical results and the experimental data was possible only at the combustor exit, due to the limitation on the measurement techniques, one can reiterate that the combination of the following sub-models: thermodynamically consistent model for the turbulence modulation, Langmuir-Knudsen non-equilibrium model for the evaporation, Reynolds Stress Model for the turbulence and flamelet model for the chemistry establish a reliable complete model that seems to allows a better description of reactive multi-phase flow studied in the frame of this work.
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Dudebout, Rudolph, Bob Reynolds e Khosro Molla-Hosseini. "Integrated Process for CFD Modeling and Optimization of Gas Turbine Combustors". In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54011.
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Honeywell Engines, Systems & Services has developed the Advanced Combustion Tool (ACT) CFD process to rapidly analyze the performance of a combustor configuration from a given fuel injector, CAD geometry and engine cycle information. ACT integrates and streamlines the traditional steps of generating and specifying geometry, mesh, physical models, boundary conditions, initial conditions, convergence criteria and post-processing. Notably, ACT utilizes several key features to reduce cycle time and improve fidelity in the CFD analysis process: a high-pressure spray diagnostic facility to obtain fuel droplet boundary conditions, feature-based macros to parametrically automate geometry and mesh generation, preprocessors to simplify and standardize boundary condition and physical model specification, and post-processors to provide graphical and analytical responses. This integrated process for CFD modeling and optimization is the subject of this paper. A demonstration of this process is the numerical prediction of the TFE731-60 combustor flowfield on a 30 degree sector model compared to experimentally measured results.
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Hiner, S. D., e R. K. Mudge. "Gas Turbine Intake Systems: High Velocity Filtration for Marine GT Installations — Part 2". In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38873.
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Following the development of a high velocity spray eliminator system for marine gas turbines, a sea trial has been completed on board a Royal Navy vessel, for back to back comparison with a unit of conventional design. This paper, will give a brief overview of the trial fit to HMS Coventry. It will then continue by presenting in detail the data obtained throughout the trial and showing the resulting comparisons between the new high velocity and conventional designs. The initial and final inspections of both engines will be presented and the appraisal by Rolls Royce, the engine design authority, will be discussed. Conclusions will be drawn detailing the suitability of the new high velocity design for use onboard RN vessels, to protect their gas turbine intakes. Design parameters for the intakes of the WR21 will be proposed to demonstrate the system’s potential benefits.
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Araki, Hidefumi, Shinichi Higuchi, Tomomi Koganezawa, Shinya Marushima, Shigeo Hatamiya e Moriaki Tsukamoto. "Test Results From the Advanced Humid Air Turbine System Pilot Plant: Part 2—Humidification, Water Recovery and Water Quality". In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51089.
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The AHAT (advanced humid air turbine) system has been studied to improve thermal efficiency of gas turbine power generation. This is an original gas turbine power generation system which substitutes the WAC (water atomization cooling) system for the intercooler system of the HAT cycle. A pilot plant was built to verify feasibility of the AHAT system, which is composed of a gas turbine, a humidification tower, a recuperator and a water recovery system. Firstly, characteristics of the humidification tower were examined. The experimental results of the humidification rate agreed with the calculation results within a deviation of 1%. Humidification increased the heat recovery, and the electrical efficiency exceeded 40%. Secondly, characteristics of the spray-type water recovery system were examined. 95% of water consumed by the humidification tower was recovered, and a significant reduction of the make-up water for the HAT cycle was confirmed. Thirdly, concentrations of impurities within the circulating water of the AHAT system were measured when the recovered water was recycled without any purification process.
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Dvornak, Michael. "Development of Engine Intake Anti-Icing Systems for LCAC". In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27240.
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US Navy ships operating in cold weather require the protection of an engine intake air anti-ice system to prevent blockage of combustion airflow during snow and icing conditions. This requirement does not present any unusual design demands on large displacement type ships because there is more available space, an abundance of usable thermal energy, and lastly their design allows engine weather intakes to be placed in relatively protected locations. However on small craft such as the Navy’s Landing Craft Air Cushion (LCAC), intake air anti-icing presents a unique design challenge. This is due to the spray generated by venting of the craft’s pressurized air cushion during normal over-water operations that results in significant carry-over of this spray onto the cargo deck, from which it is subsequently ingested into the engine intakes. LCAC is also powered by gas turbines that require large quantities of inlet combustion air for power generation. Because of these considerations the thermal energy required for intake anti-icing on LCAC are significantly higher than for large displacement type ships. Adding to this challenge are the facts that on-board space in an air cushion vehicle is at a premium, and power for thermal energy must be obtained from existing sources whose primary function is other than anti-icing. This paper will trace the development and evolution of LCAC’s engine intake anti-ice systems from the craft’s initial design, through to the present systems used in the fleet. It will present the tradeoff issues that effected selection of the anti-ice systems, such as energy availability, cold weather criteria, and craft design constraints.
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Mudge, R. K., e S. D. Hiner. "Gas Turbine Intake Systems-High Velocity Filtration for Marine Gas Turbine Installations". In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0584.
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The Royal Navy (RN) has operated marinised industrial and aero-derivative propulsion gas turbines since the late 1940’s. In order to safeguard the gas turbines (principally from foreign object damage (FOD) and salt ingestion) the RN places a high degree of importance on the gas turbine intake system, a principal element within which is the intake filtration equipment. Since the introduction of marine gas turbines the RN have witnessed and participated in the development of intake filtration systems from knitmesh filters to highly efficient 3 stage (vane- coalescer-vane) separators (spray eliminators). The requirements for RN gas turbine intake systems are described in Naval Engineering Standard (NES 312), and have been brought about by long standing operational experience of these systems and commercial best practice. This paper will briefly outline the RN design criteria for gas turbine intake systems and how this has been modified by field experience. It will then go on to look at intake separators, giving their design criteria and describe from inception, a study into the possible adoption of next generation high velocity spray eliminators describing initial specification, the product design process and development testing. The potential benefits afforded by such a high velocity system will also be discussed. In addition the paper will describe the initial fit of a trial unit onto HMS Coventry, for back to back testing with a unit of conventional design. It is intended to present Part 2 of this paper at ASME 2002 Amsterdam, which will contain a précis of the design, presentation of the data from the sea trial and the results and conclusions from the engine inspections, including an assessment by Rolls Royce the engine Design Authority. At this time the sutability of the equipment for the intakes of the WR21 will be considered.