An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25―100 μm. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to...An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25―100 μm. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to visually observe the bubble dynamics. For highly subcooled boiling at moderate heat fluxes, the bubbles generally remained attached to the micro heating wires and bubble-top jet flows were clearly observed. Smaller bubbles usually had stronger bubble-top jet flows, while larger bubbles seemed to produce multi-jet flows. The structures of the bubble-top jet flows, as well as multi-jet flows, were proposed from the experimental observation. A model was developed to describe jet flow phenomena from bubbles on micro wires. Numerical simulations for bubbles having diameter of 0.03 and 0.06 mm showed that both the bubble-top and multi-jet flows were induced by a strong Marangoni effect due to high temperature gradients near the wire. The predicted velocity magnitudes and flow structures agreed very well with experimental measurements. The bubble size relative to the wire is an important factor affecting the jet flow structure. For a 0.03 mm bubble on a 0.1 mm wire, only a bubble-top jet flow forms, while a complex multi-jet flow pattern forms around the bubble with a weak bubble-top jet and two side jet flows for a 0.06 mm bubble.展开更多
In this paper,using the computational fluid dynamics based on Euler Lagrange and the commercial software Barracuda VR,the gas-particle hydrodynamics and the erosion of particles on the inner wall and internal componen...In this paper,using the computational fluid dynamics based on Euler Lagrange and the commercial software Barracuda VR,the gas-particle hydrodynamics and the erosion of particles on the inner wall and internal components of the spouted bed in the integrated multi-jet swirling spout-fluidized bed(IMSSFB)are studied.Erosion experiments have obtained the characterization of particle erosion on internal components and verified the relevant numerical models.The results show that:the particle distribution within the IMSSFB is uneven due to the cyclonic effect of the axial swirl vane(ASV),resulting in particle erosion for the ASV being concentrated on one side;when the gas reaches the top,too high an erosion gas velocity leads to gas backflow.As the filling height increases,there is a tendency for the erosion position of the particles on the ASV to expand upwards.However,the effect of increasing gas velocity on the erosion position is insignificant.展开更多
The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet syst...The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet system was used. The aim of my previous publications and even this article is to achieve that by using of multi-jet plasma system, samples were achieved that will not be damaged coating after the bending. Specific coats on the sheets have been optimized composition of the plasma so that its result was the maximum adhesion of the coating to the steel base of samples. Results of experiments are presented in article. The article focuses on the tensile test and the result of the tensile test. All important values of tensile tests are published in this article. For example: elongation A<sub>50</sub>, A<sub>g</sub>, tensile strength R<sub>m</sub>, and yield strength R<sub>p0.2</sub>. Results with values of tensile tests are also presented in this article. Selected coated steel samples were photographed in the clamped in jig on the tension device. Group selected samples were divided by the applied coating. First, the basecoat, the final coat and coat were treated with a multi-jet plasma system. From a previous publication graphs show the dependence of the strength on elongation of a sample. Further research will be focused on selected coated samples, where samples are etched onto the surface of a network and are bent in a special jig in range bending radius R11 to R35. After bending, the samples are examined at a special optical device and are evaluated deformation circles in straight and bent part of the samples.展开更多
Fully inkjet-printed three-dimensional(3D)objects with integrated metal provide exciting possibilities for on-demand fabrication of radio frequency electronics such as inductors,capacitors,and filters.To date,there ha...Fully inkjet-printed three-dimensional(3D)objects with integrated metal provide exciting possibilities for on-demand fabrication of radio frequency electronics such as inductors,capacitors,and filters.To date,there have been several reports of printed radio frequency components metallized via the use of plating solutions,sputtering,and low-conductivity pastes.These metallization techniques require rather complex fabrication,and do not provide an easily integrated or versatile process.This work utilizes a novel silver ink cured with a low-cost infrared lamp at only 80℃,and achieves a high conductivity of 1×10^(7) S m^(−1).By inkjet printing the infrared-cured silver together with a commercial 3D inkjet ultraviolet-cured acrylic dielectric,a multilayer process is demonstrated.By using a smoothing technique,both the conductive ink and dielectric provide surface roughness values of <500 nm.A radio frequency inductor and capacitor exhibit state-of-the-art quality factors of 8 and 20,respectively,and match well with electromagnetic simulations.These components are implemented in a lumped element radio frequency filter with an impressive insertion loss of 0.8 dB at 1 GHz,proving the utility of the process for sensitive radio frequency applications.展开更多
This article focuses on the study of the defined values of tensile strain and the effect of low temperature plasma adhesion selected coatings on steel samples using a tensile testing flat test bars. Samples were made ...This article focuses on the study of the defined values of tensile strain and the effect of low temperature plasma adhesion selected coatings on steel samples using a tensile testing flat test bars. Samples were made by machining and welding technologies. The flat test bars were tested by pulling on a test rig UPC 1200. Part of the samples was treated on the surface prior to coating by a tensile test, second base coat and with a final coat continuous multi plasma system. The selected test samples were determined from the tensile test of the material characteristics apparent from the tensile diagrams. The examined samples were fitted top and base coat. Another group was the KTL basis. The presented graphs show the dependence of the strength on elongation of a sample according to DIN EN ISO 6892-2. The samples were then examined under a stereo microscope SCHUT brand, type SSM-E in the laboratory to conduct coating on a steel sheet at the moment of total violation sectional samples. The base layer, in which the temperature ranges from 160°C - 180°C, was applied by electrophoresis method.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No,5997601 6)the Graduate Foundation of Tsinghua University.
文摘An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25―100 μm. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to visually observe the bubble dynamics. For highly subcooled boiling at moderate heat fluxes, the bubbles generally remained attached to the micro heating wires and bubble-top jet flows were clearly observed. Smaller bubbles usually had stronger bubble-top jet flows, while larger bubbles seemed to produce multi-jet flows. The structures of the bubble-top jet flows, as well as multi-jet flows, were proposed from the experimental observation. A model was developed to describe jet flow phenomena from bubbles on micro wires. Numerical simulations for bubbles having diameter of 0.03 and 0.06 mm showed that both the bubble-top and multi-jet flows were induced by a strong Marangoni effect due to high temperature gradients near the wire. The predicted velocity magnitudes and flow structures agreed very well with experimental measurements. The bubble size relative to the wire is an important factor affecting the jet flow structure. For a 0.03 mm bubble on a 0.1 mm wire, only a bubble-top jet flow forms, while a complex multi-jet flow pattern forms around the bubble with a weak bubble-top jet and two side jet flows for a 0.06 mm bubble.
基金supported by the National Natural Science Foundation of China(22178286)Shaanxi Qin Chuangyuan“scientist and engineer”team construction project(2022KXJ-041)。
文摘In this paper,using the computational fluid dynamics based on Euler Lagrange and the commercial software Barracuda VR,the gas-particle hydrodynamics and the erosion of particles on the inner wall and internal components of the spouted bed in the integrated multi-jet swirling spout-fluidized bed(IMSSFB)are studied.Erosion experiments have obtained the characterization of particle erosion on internal components and verified the relevant numerical models.The results show that:the particle distribution within the IMSSFB is uneven due to the cyclonic effect of the axial swirl vane(ASV),resulting in particle erosion for the ASV being concentrated on one side;when the gas reaches the top,too high an erosion gas velocity leads to gas backflow.As the filling height increases,there is a tendency for the erosion position of the particles on the ASV to expand upwards.However,the effect of increasing gas velocity on the erosion position is insignificant.
文摘The article used new experimental equipment for effective testing of adhesion coatings on the sheets. Testing was performed in jig by bending roller with selected radius. In the context of experiments a multi-jet system was used. The aim of my previous publications and even this article is to achieve that by using of multi-jet plasma system, samples were achieved that will not be damaged coating after the bending. Specific coats on the sheets have been optimized composition of the plasma so that its result was the maximum adhesion of the coating to the steel base of samples. Results of experiments are presented in article. The article focuses on the tensile test and the result of the tensile test. All important values of tensile tests are published in this article. For example: elongation A<sub>50</sub>, A<sub>g</sub>, tensile strength R<sub>m</sub>, and yield strength R<sub>p0.2</sub>. Results with values of tensile tests are also presented in this article. Selected coated steel samples were photographed in the clamped in jig on the tension device. Group selected samples were divided by the applied coating. First, the basecoat, the final coat and coat were treated with a multi-jet plasma system. From a previous publication graphs show the dependence of the strength on elongation of a sample. Further research will be focused on selected coated samples, where samples are etched onto the surface of a network and are bent in a special jig in range bending radius R11 to R35. After bending, the samples are examined at a special optical device and are evaluated deformation circles in straight and bent part of the samples.
文摘Fully inkjet-printed three-dimensional(3D)objects with integrated metal provide exciting possibilities for on-demand fabrication of radio frequency electronics such as inductors,capacitors,and filters.To date,there have been several reports of printed radio frequency components metallized via the use of plating solutions,sputtering,and low-conductivity pastes.These metallization techniques require rather complex fabrication,and do not provide an easily integrated or versatile process.This work utilizes a novel silver ink cured with a low-cost infrared lamp at only 80℃,and achieves a high conductivity of 1×10^(7) S m^(−1).By inkjet printing the infrared-cured silver together with a commercial 3D inkjet ultraviolet-cured acrylic dielectric,a multilayer process is demonstrated.By using a smoothing technique,both the conductive ink and dielectric provide surface roughness values of <500 nm.A radio frequency inductor and capacitor exhibit state-of-the-art quality factors of 8 and 20,respectively,and match well with electromagnetic simulations.These components are implemented in a lumped element radio frequency filter with an impressive insertion loss of 0.8 dB at 1 GHz,proving the utility of the process for sensitive radio frequency applications.
基金supported by project Technical University in Brno,Faculty of Mechanical Engineering:BUT FME-S-12-5 from 2012 and VAV 13313.
文摘This article focuses on the study of the defined values of tensile strain and the effect of low temperature plasma adhesion selected coatings on steel samples using a tensile testing flat test bars. Samples were made by machining and welding technologies. The flat test bars were tested by pulling on a test rig UPC 1200. Part of the samples was treated on the surface prior to coating by a tensile test, second base coat and with a final coat continuous multi plasma system. The selected test samples were determined from the tensile test of the material characteristics apparent from the tensile diagrams. The examined samples were fitted top and base coat. Another group was the KTL basis. The presented graphs show the dependence of the strength on elongation of a sample according to DIN EN ISO 6892-2. The samples were then examined under a stereo microscope SCHUT brand, type SSM-E in the laboratory to conduct coating on a steel sheet at the moment of total violation sectional samples. The base layer, in which the temperature ranges from 160°C - 180°C, was applied by electrophoresis method.
