Impact Velocity and Surface Temperature Effects on the Collision of a Molten Tin Droplet on a Solid Surface PDF Download
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Author: Shiraz Dean Aziz
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
An experimental investigation was performed on the splashing and freezing of molten tin droplets on a stainless steel surface. The diameter of the droplets was 2.7 mm, and the impact velocity ranged from 1.0 m/s to 4.0 m/s. The substrate temperature was varied from 25$\sp\circ$C to 240$\sp\circ$C. Droplet impact was photographed using a 35 mm camera; both the splat diameter and liquid-solid contact angle were measured from these photographs. The substrate temperature under the impacting droplet was measured using a fast response thermocouple. The heat transfer coefficient during the first 0.5 ms of impact was obtained by matching measured surface temperature variation with an analytical solution. A simple energy conservation model was used to predict the maximum spreading of the droplet during impact. The predictions agreed well with experimental values. Instabilities were observed on the periphery of the droplet, which led to the formation of a finger pattern at velocities above 1.0 m/s. A model based on the Rayleigh-Taylor instability was used to predict the number of fingers around the periphery of the droplet.
Author: Shiraz Dean Aziz
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
An experimental investigation was performed on the splashing and freezing of molten tin droplets on a stainless steel surface. The diameter of the droplets was 2.7 mm, and the impact velocity ranged from 1.0 m/s to 4.0 m/s. The substrate temperature was varied from 25$\sp\circ$C to 240$\sp\circ$C. Droplet impact was photographed using a 35 mm camera; both the splat diameter and liquid-solid contact angle were measured from these photographs. The substrate temperature under the impacting droplet was measured using a fast response thermocouple. The heat transfer coefficient during the first 0.5 ms of impact was obtained by matching measured surface temperature variation with an analytical solution. A simple energy conservation model was used to predict the maximum spreading of the droplet during impact. The predictions agreed well with experimental values. Instabilities were observed on the periphery of the droplet, which led to the formation of a finger pattern at velocities above 1.0 m/s. A model based on the Rayleigh-Taylor instability was used to predict the number of fingers around the periphery of the droplet.
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Category :
Languages : en
Pages :
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Author: Rabindra Bhola
Publisher:
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Category :
Languages : en
Pages : 0
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Book Description
The collision and freezing of molten tin droplets on a surface was studied. The objectives of this work were: first to examine the effect of substrate temperature, substrate material, and substrate geometry on droplet impact dynamics; second, to measure surface temperature variation during impact to estimate the thermal contact resistance at the droplet/substrate interface; and finally, to propose an analytical model to estimate solidification effect on the maximum droplet spread. Impacts on a stainless steel surface set at different temperatures showed significant effect of solidification on droplet impact; solidification restricted droplet motion, particularly in recoil. Substrate material had a less dramatic effect on droplet impact dynamics. The model of maximum spread with the effect of solidification agreed well with the experiments. Results of the images impacting on the step and incline surfaces showed complex fluid flow which can only be simulated by a numerical model.
Author:
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ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 776
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Author: Hani Henein
Publisher: Springer
ISBN: 3319526898
Category : Technology & Engineering
Languages : en
Pages : 569
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Book Description
This book describes and illustrates metal spray and spray deposition from the process engineering, metallurgical, and application viewpoints. The authors include step-by-step fundamental information for the metal spray process and detail current engineering developments and applications. They offer industry insight on non-equilibrium solidification processes for yielding stable metal structures and properties.
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Category :
Languages : en
Pages :
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Author: Kalpak Prakash Gatne
Publisher:
ISBN:
Category :
Languages : en
Pages : 105
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Book Description
A study of the normal impact of liquid droplets on a dry horizontal substrate is presented in this thesis. The impact dynamics, spreading and recoil behavior are captured using a high-speed digital video camera at 2000 frames per second. A digital image processing software was used to determine the drop spread and height of the liquid on the surface from each frame. To ascertain the effects of liquid viscosity and surface tension, experiments were conducted with four pure liquids (water, ethanol, propylene glycol and glycerin) that have vastly different fluid properties. Three different Weber numbers (20, 40, and 80) were considered by altering the height from which the drop is released. To understand the influence of drop size, experiments were performed in which the drop size was varied for the same fluid. Also, the effect of substrate material was studied by comparing the impact on two different substrates: glass (hydrophilic) and PTFE or Teflon (hydrophobic). The high-speed photographs of impact, spreading and recoil are shown and the temporal variations of dimensionless drop spread and height are provided in the paper. Experiments were performed to study the influence of addition of surface active agents or surfactants in aqueous solution on the droplet impact phenomenon. Three surfactants were used with varying diffusion rates: SDS (anionic), CTAB (cationic) and Triton x 100 (non ionic). The spreading and recoil of the drops of surfactant solutions is studied at concentrations of half the critical micelle concentration (CMC) and twice CMC. To underscore the dynamic effects, comparative experiments for the three surfactants were performed so that all the solutions had the same value of equilibrium surface tension. The role played by impact velocity in the collision of surfactant laden drops was studied by comparing the results for two different impact velocities. The influence of surfactant concentration was studied by performing experiments varying the surfactant concentrations. The results show that changes in liquid viscosity, surface tension, and surfactant concentration significantly affect the spreading and recoil behavior. In the case of pure liquids, for a fixed Weber number, lower surface tension promotes greater spreading and higher viscosity dampens spreading and recoil. Using a simple scale analysis of energy balance, it was found that the maximum spread factor varies as Re 1/5when liquid viscosity is high and viscous effects govern the spreading behavior. The drop size had no binding when the Weber number was maintained constant and the Reynolds numbers were comparable. The nature of the substrate plays a very important role. Impact on hydrophobic substrates can result in dramatic recoils and rebound. For aqueous solutions with surface active agents, it was observed that higher diffusion rate surfactants result in higher spreading factors and weaker oscillations. The spreading and recoil behavior can be correlated to the dynamic surface tension response of the surfactant solutions. With increase in impact velocity, the gain in spreading factor over a pure water drop decreases. Also, lowering of the surfactant concentration results in lower spreading factor and stronger recoil - a behavior closer to that of pure water.
Author: Saeid Shakeri Siavoshani
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The impact of molten metal droplets on a flat surface was studied experimentally. A single shot photographic technique was used to photograph droplet impact, and the spread factor and number of fingers around a splashing drop were measured from these photographs. Experiments were done using stainless steel and glass substrates with different roughness. The stainless steel surface temperature was varied from 25°C to 240°C. The initial temperature of tin droplets was maintained at either 246°C or 384°C. Some experiments were done on the impact of molten zinc droplets. A simple energy conservation model was used to estimate the thermal contact resistance between the droplet and surface. Increasing surface roughness was found to increase thermal contact resistance. Increasing surface roughness reduced the number of fingers while increasing their size. When one droplet lands on another, the final splat shape depends on the distance between droplet centers.
Author: Jie Liu
Publisher:
ISBN:
Category : Lasers
Languages : en
Pages : 280
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Book Description
![Measuring Thermal Contact Resistance Under an Impacting Droplet of Molten Metal [microform] PDF](https://books.google.com/books/content/images/frontcover/A9uBtgAACAAJ?fife=w80-h100)
Author: Yoav Heichal
Publisher: Library and Archives Canada = Bibliothèque et Archives Canada
ISBN: 9780494025222
Category :
Languages : en
Pages : 218
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Book Description
An experimental investigation was performed on the thermal contact resistance values between molten metal droplets and metal substrates. Droplet impact was photographed and substrate surface temperature variation under the impacting droplet was measured using ultra fast temperature sensors that were developed especially for the purposes of this research. The thermal contact resistance during the first few milliseconds of impact was obtained by matching measured surface temperature variation with an analytical solution of the 1-D transient conduction equation. The process was repeated for different surface roughness, different impact velocity and different surface contaminations. An analytical model was developed in order to predict the contact resistance values by estimating the true area of contact between liquid metal and a rough solid. The test results agreed well with the analytical model predictions. Thermal contact resistance increased moderately with an increase in surface roughness, decrease in contact pressure and the presence of surface contaminations.
