Visual Study of Hollow Cone Water Spray Jet Breakup Process at Elevated Temperatures and Pressures

2013 ◽  
Vol 465-466 ◽  
pp. 485-489 ◽  
Author(s):  
Muhammad Yasin Naz ◽  
Shaharin A. Sulaiman ◽  
Bambang Ari-Wahjoedi ◽  
Ku Zilati Ku Shaari
Keyword(s):  
Elevated Temperatures ◽  
Heating Temperature ◽  
Hot Water ◽  
Spray Parameters ◽  
Water Spray ◽  
Hollow Cone ◽  
Spray Cone ◽  
Load Pressure ◽  
Breakup Mechanism ◽  
Jet Breakup

The liquid jet breakup is a ubiquitous phenomenon in nature and a classic problem in hydrodynamics. The understanding of the jet breakup mechanism of hot liquids is still a challenge for researchers. The objective of this work was to understand and control the hot water spray jet breakup mechanism at moderate pumping pressures and elevated temperature. For this purpose, the visual and comparative studies were conducted on hollow cone water spray patterns generated by three hollow cone spray nozzles which were installed in an in-house built intermittently forced liquid spraying system. 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 spray characteristics. It was also predicted that heated liquids generate the dispersed spray patterns and the induction of thermal energy into the system enhances the jet disintegration ability. The spray cone width and angle were not varied significantly whereas the Weber and Reynolds numbers along with other spray parameters showed an appreciable response to the load pressure and water heating temperature at early stages of water injection.

scholarly journals Investigation of Vortex Clouds and Droplet Sizes in Heated Water Spray Patterns Generated by Axisymmetric Full Cone Nozzles

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
M. Y. Naz ◽  
S. A. Sulaiman ◽  
B. Ariwahjoedi ◽  
Ku Zilati Ku Shaari
Keyword(s):  
Nozzle Exit ◽  
High Speed ◽  
Heating Temperature ◽  
Cone Angle ◽  
Hot Water ◽  
Orifice Diameter ◽  
Detailed Knowledge ◽  
Water Spray ◽  
Spray Cone ◽  
Load Pressure

The hot water sprays are an important part of many industrial processes, where the detailed knowledge of physical phenomena involved in jet transportation, interaction, secondary breakup, evaporation, and coalescence of droplets is important to reach more efficient processes. The objective of the work was to study the water spray jet breakup dynamics, vortex cloud formation, and droplet size distribution under varying temperature and load pressure. Using a high speed camera, the spray patterns generated by axisymmetric full cone nozzles were visualized as a function water temperature and load pressure. The image analysis confirmed that the spray cone angle and width do not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The formation and decay of semitorus like vortex clouds were also noticed in spray structures generated at near water boiling point temperature. For the nozzle with smallest orifice diameter (1.19 mm), these vortex clouds were very clear at 90°C heating temperature and 1 bar water load pressure. In addition, the sauter mean diameter (SMD) of the spray droplets was also measured by using Phase Doppler Anemometry (PDA) at different locations downstream of the nozzle exit. It was noticed that SMD varies slightly w.r.t. position when measured at room temperature whereas at higher temperature values, it became almost constant at distance of 55 mm downstream of the nozzle exit.

Experimental Study of Airless Spray Jet Breakup at Elevated Temperature and Pressure

2013 ◽  
Vol 393 ◽  
pp. 711-716 ◽  
Author(s):  
Muhammad Yasin Naz ◽  
Shaharin Anwar Sulaiman ◽  
Bambang Ari-Wahjoedi
Keyword(s):  
High Speed ◽  
Water Injection ◽  
Research Work ◽  
Ambient Air ◽  
High Water ◽  
Processing Parameters ◽  
Spray Cone ◽  
Load Pressure ◽  
Breakup Mechanism ◽  
Jet Breakup

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.

scholarly journals Characterization of Modified Tapioca Starch Solutions and Their Sprays for High Temperature Coating Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. Y. Naz ◽  
S. A. Sulaiman ◽  
B. Ariwahjoedi ◽  
Ku Zilati Ku Shaari
Keyword(s):  
High Speed ◽  
Heating Temperature ◽  
Complex Viscosity ◽  
Effect Of Temperature ◽  
Mean Flow ◽  
Spray Cone ◽  
Load Pressure ◽  
Tapioca Starch ◽  
Jet Breakup

The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature.

Effect of Viscosity and Heating Temperature on an Intermittent Spray Jet of Starch Dispersion

2014 ◽  
Vol 695 ◽  
pp. 459-462
Author(s):  
Muhammad Yasin Naz ◽  
Shaharin Anwar Sulaiman ◽  
Bambang Ari-Wahjoedi
Keyword(s):  
High Speed ◽  
Heating Temperature ◽  
Cone Angle ◽  
Imaging Study ◽  
Injection Time ◽  
Jet Injection ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Load Pressure ◽  
Jet Breakup

In this paper, an attempt was made to integrate the effect of jet injection time, load pressure and solution physical properties on jet breakup parameters. A starch-urea-borax complex solution was prepared and tested with an axi-symmetric full cone nozzle. The jet injection time was set to 100, 200, 300 and 400, the solution heating temperature was set to 20°C and 80°C ms, the load pressure was set to 1, 2, 3, 4, and 5 bar, and corresponding spray patterns were imaged by using a high speed camera. The imaging study of the developing spray patterns revealed that the unheated solution forms only spinning jets for all used load pressures. No jet breakup was seen in the near and far-nozzle imaged regions except at 5 bar load pressure, where minor spreading in the jet was seen after 80 mm downstream of the nozzle exit. At 80°C temperature and 5 bar load pressure, very dense spray patterns with an increased spray cone angle were emerging from the nozzle. After 300 ms of injection time, these developing spray jets were changed into fine spray patterns.

Effect of Powder Properties such as Particle Size, Density and Melt Flow Rate on the Properties of Flame Sprayed PE Coating

2000 ◽  
Author(s):  
E. Rajamäki ◽  
M. Leino ◽  
P. Vuoristo ◽  
P. Järvelä ◽  
T. Mäntylä
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Flow Rate ◽  
Heating Temperature ◽  
Steel Substrate ◽  
Great Influence ◽  
Hot Water ◽  
Melt Flow ◽  
Melt Flow Rate ◽  
Powder Properties

Abstract Three different types of polyethylene powders were flame sprayed onto pre-heated steel substrate previously coated by electrostatic spray system with a thin epoxy primer layer. Properties of the polyethylene (PE) powders, including powder density, particle size and melt flow rate (MFR) were measured in order to study their influence on the mechanical properties of the coating. The spray experiments started with optimization of spraying parameters. The main variables were pre-heating temperature of the substrate, temperature increase during spraying (influenced by the spraying distance), and thickness of the PE coatings. The laboratory tests performed for the coatings were coating characterization by microscopy and mechanical testing. Porosity and thickness of the coatings were determined by optical and stereo microscopy studies from polished cross-sectional samples. Hardness, impact strength, peel strength, and adhesive strength of the coatings were also investigated. Also some hot water sinking and heat cycling tests were performed. As a result from the present studies it can be concluded that powder properties have great influence on the mechanical properties of the final coating.

Influence of fuel volatility on combustion and emission characteristics in a gas turbine combustor at different inlet pressures and swirl conditions

2002 ◽  
Vol 216 (3) ◽  
pp. 257-268 ◽  
Author(s):  
N. Y. Sharma ◽  
S. K. Som
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Combustion Efficiency ◽  
Inlet Pressure ◽  
Emission Characteristics ◽  
Spray Parameters ◽  
Gas Turbine Combustor ◽  
Spray Cone ◽  
Emission Level ◽  
Inlet Swirl

The practical challenges in research in the field of gas turbine combustion mainly centre around a clean emission, a low liner wall temperature and a desirable exit temperature distribution for turboma-chinery applications, along with fuel economy of the combustion process. An attempt has been made in the present paper to develop a computational model based on stochastic separated flow analysis of typical diffusion-controlled spray combustion of liquid fuel in a gas turbine combustor to study the influence of fuel volatility at different combustor pressures and inlet swirls on combustion and emission characteristics. A κ-ɛ model with wall function treatment for the near-wall region has been adopted for the solution of conservation equations in gas phase. The initial spray parameters are specified by a suitable probability distribution function (PDF) size distribution and a given spray cone angle. A radiation model for the gas phase, based on the first-order moment method, has been adopted in consideration of the gas phase as a grey absorbing-emitting medium. The formation of thermal NO x as a post-combustion reaction process is determined from the Zeldovich mechanism. It has been recognized from the present work that an increase in fuel volatility increases combustion efficiency only at higher pressures. For a given fuel, an increase in combustor pressure, at a constant inlet temperature, always reduces the combustion efficiency, while the influence of inlet swirl is found to decrease the combustion efficiency only at higher pressure. The influence of inlet pressure on pattern factor is contrasting in nature for fuels with lower and higher volatilities. For a higher-volatility fuel, a reduction in inlet pressure decreases the value of the pattern factor, while the trend is exactly the opposite in the case of fuels with lower volatilities. The NOx emission level increases with decrease in fuel volatility at all combustor pressures and inlet swirls. For a given fuel, the NOx emission level decreases with a reduction in combustor pressure and an increase in inlet swirl number.

scholarly journals Resistance of thermally modified and pressurized hot water extracted Scots pine sapwood against decay by the brown-rot fungus Rhodonia placenta

2019 ◽  
Vol 78 (1) ◽  
pp. 161-171 ◽  
Author(s):  
Michael Altgen ◽  
Suvi Kyyrö ◽  
Olli Paajanen ◽  
Lauri Rautkari
Keyword(s):  
Cell Wall ◽  
Mass Loss ◽  
Scots Pine ◽  
Elevated Temperatures ◽  
Brown Rot ◽  
Decay Resistance ◽  
Hot Water ◽  
Decay Fungi ◽  
Effective Reduction ◽  
Cell Wall Porosity

AbstractThe thermal degradation of wood is affected by a number of process parameters, which may also cause variations in the resistance against decay fungi. This study compares changes in the chemical composition, water-related properties and decay resistance of Scots pine sapwood that was either thermally modified (TM) in dry state at elevated temperatures (≥ 185 °C) or treated in pressurized hot water at mild temperatures (≤ 170 °C). The thermal decomposition of easily degradable hemicelluloses reduced the mass loss caused by Rhodonia placenta, and it was suggested that the cumulative mass loss is a better indicator of an actual decay inhibition. Pressurized hot water extraction (HWE) did not improve the decay resistance to the same extent as TM, which was assigned to differences in the wood-water interactions. Cross-linking reactions during TM caused a swelling restraint and an effective reduction in moisture content. This decreased the water-swollen cell wall porosity, which presumably hindered the transport of degradation agents through the cell wall and/or reduced the accessibility of wood constituents for degradation agents. This effect was absent in hot water-extracted wood and strong decay occurred even when most hemicelluloses were already removed during HWE.

scholarly journals Behavior Deterioration and Microstructure Change of Polyvinyl Alcohol Fiber-Reinforced Cementitious Composite (PVA-ECC) after Exposure to Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5539
Author(s):  
Qing Wang ◽  
Boyu Yao ◽  
Runze Lu
Keyword(s):  
Polyvinyl Alcohol ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
Polymer Fibers ◽  
Cementitious Composites ◽  
Cementitious Composite ◽  
Fiber Reinforced ◽  
Explosive Spalling ◽  
Polyvinyl Alcohol Fiber ◽  
Dense Microstructure

In the case of fire, explosive spalling often occurs in cementitious composites due to dense microstructure and high pore-pressure. Polymer fibers were proved to be effective in mitigating such behavior. However, deterioration of these fiber-reinforced cementitious composites inevitably occurs, which is vital for the prediction of structural performance and prevention of catastrophic disaster. This paper concentrates on the behavior and mechanism of the deterioration of polyvinyl alcohol fiber-reinforced engineered cementitious composite (PVA-ECC) after exposure to elevated temperatures. Surface change, cracking, and spalling behavior of the cubic specimens were observed at room temperature, and after exposure to 200 °C, 400 °C, 600 °C, 800 °C, and 1200 °C. Losses in specimen weight and compressive strength were evaluated. Test results indicated that explosive spalling behavior was effectively prevented with 2.0 vol% polyvinyl alcohol fiber although the strength monotonically decreased with heating temperature. X-ray diffraction curves showed that the calcium hydroxide initially decomposed in the range of 400–600 °C, and finished beyond 600 °C, while calcium silicate hydrate began at around 400 °C and completely decomposed at approximately 800 °C. Micrographs implied a reduction in fiber diameter at 200 °C, exhibiting apparent needle-like channels beyond 400 °C. When the temperature was increased to 600 °C and above, the dents were gradually filled with newly produced substance due to the synergistic effect of thermal expansion, volume expansion of chemical reactions, and pore structure coarsening

scholarly journals Heating Temperature Prediction of Concrete Structure Damaged by Fire Using a Bayesian Approach

2020 ◽  
Vol 12 (10) ◽  
pp. 4225
Author(s):  
Hae-Chang Cho ◽  
Sun-Jin Han ◽  
Inwook Heo ◽  
Hyun Kang ◽  
Won-Hee Kang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
Model Development ◽  
Estimation Model ◽  
Temperature Estimation ◽  
Rc Structures ◽  
Material Development ◽  
Rc Structure ◽  
Eurocode 2

A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 °C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application.

Visual characterization of heated water spray jet breakup induced by full cone spray nozzles

2015 ◽  
Vol 56 (2) ◽  
pp. 211-219 ◽  
Author(s):  
M. Y. Naz ◽  
S. A. Sulaiman ◽  
B. Ariwahjoedi ◽  
K. Zilati
Keyword(s):  
Water Spray ◽  
Heated Water ◽  
Jet Breakup
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