The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Qi Liu - One of the best experts on this subject based on the ideXlab platform.
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Coupling Diffusion Welding Technique and Mesh Screen Creates Heterogeneous Metal Surface for Droplets Array
Advanced Materials Interfaces, 2017Co-Authors: Jian Xie, Qi Liu, Li XiangAbstract:Nonsilicon micromachining is a challenge, especially for large scale heterogeneous (hydrophilic/hydrophobic) surface fabrication. Here, Mesh Screen and diffusion welding technique are coupled to form a novel fabrication method. Mesh Screen is used as mask. The diffusion welding technique sinters Mesh Screen on copper surface to form welding junction array. Chemical treatment of sintered package forms superhydrophobic nanostructures on surfaces except welding junction array. Separating Mesh Screen from copper substrate exposes hydrophilic dots array, corresponding to welding junction array. Thus, heterogeneous surface is created. By condensing wet air, main droplet and neighboring droplet occur on hydrophilic dot and superhydrophobic part, respectively. For horizontal surface, neighboring droplets initially generated on nanograsses behave consecutive events of coalescence, jump, and return, triggering contact/noncontact effect induced jumping. Thus, defect droplet area is formed and droplet size uniformity is broken. A nondimensional equation is proposed for the contact effect induced jumping analysis. Noncontact effect induced jumping is found for the first time. For vertical surface, droplet array behaves monodisperse size due to departure of merged neighboring droplets without returning, and equal opportunities of neighboring droplets captured by main droplets. The work opens a new way for large scale droplet array generation by controllable condensation.
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Water drop impacts on a single-layer of Mesh Screen membrane: Effect of water hammer pressure and advancing contact angles
Experimental Thermal and Fluid Science, 2017Co-Authors: Jinliang Xu, Xiaotian He, Yu Cheng, Jian Xie, Qi LiuAbstract:Mesh Screen membrane is a functional material for gas-water or oil-water separation. If a water drop impacts on the membrane at a sufficiently high velocity, a critical condition at which daughter droplets are generated and fall down below the membrane occurs, under which the separator is failure. The objective of this paper is to determine the critical condition. Six Mesh Screen membranes are used. The Mesh wire diameter and Mesh pore are on the same-scale (10–100 μm), involving apparent cross sectional area decrease of Mesh pores in the membrane depth direction. Thus, drop impacting on the membrane yields significant liquid compression in ∼μs timescale to cause additional water hammer pressure. The analysis shows that the liquid compression is related to the number of Mesh pores within drop project area (N). The water hammer pressure relative to dynamic pressure is found to be raised with N. The drop impacting process is governed by the dynamic pressure together with the additional water hammer pressure competed with the maximum capillary pressure at the throat location of the Mesh pore. The modified Weber number −Wew/cos(θA) was correlated with N in a single curve to predict the critical condition for droplet breakthrough, where Wewis characterized by the Mesh pore width and cos(θA) reflects the advancing contact angle effect. This paper is useful for membrane type gas-water or oil-water separator design.
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Large scale generation of micro-droplet array by vapor condensation on Mesh Screen piece
Scientific Reports, 2017Co-Authors: Jian Xie, Xiaotian He, Jinliang Xu, Qi LiuAbstract:We developed a novel micro-droplet array system, which is based on the distinct three dimensional Mesh Screen structure and sintering and oxidation induced thermal-fluid performance. Mesh Screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more "hydrophilic" than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the Mesh Screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.
David J Chato - One of the best experts on this subject based on the ideXlab platform.
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warm pressurant effects on the bubble point for cryogenic liquid acquisition devices
Journal of Thermophysics and Heat Transfer, 2015Co-Authors: Jaso Hartwig, Joh Mcquille, David J ChatoAbstract:This paper presents experimental results for the liquid hydrogen and nitrogen bubble point tests using warm pressurant gases conducted at the NASA Glenn Research Center. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine-Mesh Screen samples (325×2300, 450×2750, and 510×3600) were tested in liquid hydrogen and liquid nitrogen using cold and warm noncondensable (gaseous helium) and condensable (gaseous hydrogen or nitrogen) pressurization schemes. Gases were conditioned from 0–90 K above the liquid temperature. Results clearly indicate degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensable pressurization. Degradation in the bubble point pressure is inversely proportional to Screen porosity because the coarsest Mesh demonstrated the highest degradation. Results here have implication on both pressurization and liqui...
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Warm Pressurant Gas Effects on the Static Bubble Point Pressure for Cryogenic LADs
50th AIAA ASME SAE ASEE Joint Propulsion Conference, 2014Co-Authors: Jason Hartwig, John Mcquillen, David J ChatoAbstract:This paper presents experimental results for the liquid hydrogen and nitrogen bubble point tests using warm pressurant gases conducted at the NASA Glenn Research Center. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device (LAD). Three fine Mesh Screen samples (325x2300, 450x2750, 510x3600) were tested in liquid hydrogen and liquid nitrogen using cold and warm non-condensable (gaseous helium) and condensable (gaseous hydrogen or nitrogen) pressurization schemes. Gases were conditioned from 0K - 90K above the liquid temperature. Results clearly indicate degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over non-condensable pressurization. Degradation in the bubble point pressure is inversely proportional to Screen porosity, as the coarsest Mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.
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Screen channel lad bubble point tests in liquid hydrogen
International Journal of Hydrogen Energy, 2014Co-Authors: Jaso Hartwig, David J Chato, Joh McquilleAbstract:Abstract This paper presents experimental results for the liquid hydrogen bubble point tests for liquid acquisition devices (LADs) operating in low gravity cryogenic propulsion systems. The purpose of the test was to investigate parameters that affect Screen channel LAD performance in a low pressure liquid hydrogen (LH2) propellant tank and to demonstrate several ways to increase the LH2 bubble point pressure. Three fine Mesh Screen channel LAD samples were tested in LH2 over the range of 16.7 K
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Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point
49th AIAA ASME SAE ASEE Joint Propulsion Conference, 2013Co-Authors: Jason Hartwig, John Mcquillen, David J ChatoAbstract:This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine Mesh Screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to Screen porosity, as the coarsest Mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.
Jinliang Xu - One of the best experts on this subject based on the ideXlab platform.
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Water drop impacts on a single-layer of Mesh Screen membrane: Effect of water hammer pressure and advancing contact angles
Experimental Thermal and Fluid Science, 2017Co-Authors: Jinliang Xu, Xiaotian He, Yu Cheng, Jian Xie, Qi LiuAbstract:Mesh Screen membrane is a functional material for gas-water or oil-water separation. If a water drop impacts on the membrane at a sufficiently high velocity, a critical condition at which daughter droplets are generated and fall down below the membrane occurs, under which the separator is failure. The objective of this paper is to determine the critical condition. Six Mesh Screen membranes are used. The Mesh wire diameter and Mesh pore are on the same-scale (10–100 μm), involving apparent cross sectional area decrease of Mesh pores in the membrane depth direction. Thus, drop impacting on the membrane yields significant liquid compression in ∼μs timescale to cause additional water hammer pressure. The analysis shows that the liquid compression is related to the number of Mesh pores within drop project area (N). The water hammer pressure relative to dynamic pressure is found to be raised with N. The drop impacting process is governed by the dynamic pressure together with the additional water hammer pressure competed with the maximum capillary pressure at the throat location of the Mesh pore. The modified Weber number −Wew/cos(θA) was correlated with N in a single curve to predict the critical condition for droplet breakthrough, where Wewis characterized by the Mesh pore width and cos(θA) reflects the advancing contact angle effect. This paper is useful for membrane type gas-water or oil-water separator design.
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Large scale generation of micro-droplet array by vapor condensation on Mesh Screen piece
Scientific Reports, 2017Co-Authors: Jian Xie, Xiaotian He, Jinliang Xu, Qi LiuAbstract:We developed a novel micro-droplet array system, which is based on the distinct three dimensional Mesh Screen structure and sintering and oxidation induced thermal-fluid performance. Mesh Screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more "hydrophilic" than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the Mesh Screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.
Jian Xie - One of the best experts on this subject based on the ideXlab platform.
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Coupling Diffusion Welding Technique and Mesh Screen Creates Heterogeneous Metal Surface for Droplets Array
Advanced Materials Interfaces, 2017Co-Authors: Jian Xie, Qi Liu, Li XiangAbstract:Nonsilicon micromachining is a challenge, especially for large scale heterogeneous (hydrophilic/hydrophobic) surface fabrication. Here, Mesh Screen and diffusion welding technique are coupled to form a novel fabrication method. Mesh Screen is used as mask. The diffusion welding technique sinters Mesh Screen on copper surface to form welding junction array. Chemical treatment of sintered package forms superhydrophobic nanostructures on surfaces except welding junction array. Separating Mesh Screen from copper substrate exposes hydrophilic dots array, corresponding to welding junction array. Thus, heterogeneous surface is created. By condensing wet air, main droplet and neighboring droplet occur on hydrophilic dot and superhydrophobic part, respectively. For horizontal surface, neighboring droplets initially generated on nanograsses behave consecutive events of coalescence, jump, and return, triggering contact/noncontact effect induced jumping. Thus, defect droplet area is formed and droplet size uniformity is broken. A nondimensional equation is proposed for the contact effect induced jumping analysis. Noncontact effect induced jumping is found for the first time. For vertical surface, droplet array behaves monodisperse size due to departure of merged neighboring droplets without returning, and equal opportunities of neighboring droplets captured by main droplets. The work opens a new way for large scale droplet array generation by controllable condensation.
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Water drop impacts on a single-layer of Mesh Screen membrane: Effect of water hammer pressure and advancing contact angles
Experimental Thermal and Fluid Science, 2017Co-Authors: Jinliang Xu, Xiaotian He, Yu Cheng, Jian Xie, Qi LiuAbstract:Mesh Screen membrane is a functional material for gas-water or oil-water separation. If a water drop impacts on the membrane at a sufficiently high velocity, a critical condition at which daughter droplets are generated and fall down below the membrane occurs, under which the separator is failure. The objective of this paper is to determine the critical condition. Six Mesh Screen membranes are used. The Mesh wire diameter and Mesh pore are on the same-scale (10–100 μm), involving apparent cross sectional area decrease of Mesh pores in the membrane depth direction. Thus, drop impacting on the membrane yields significant liquid compression in ∼μs timescale to cause additional water hammer pressure. The analysis shows that the liquid compression is related to the number of Mesh pores within drop project area (N). The water hammer pressure relative to dynamic pressure is found to be raised with N. The drop impacting process is governed by the dynamic pressure together with the additional water hammer pressure competed with the maximum capillary pressure at the throat location of the Mesh pore. The modified Weber number −Wew/cos(θA) was correlated with N in a single curve to predict the critical condition for droplet breakthrough, where Wewis characterized by the Mesh pore width and cos(θA) reflects the advancing contact angle effect. This paper is useful for membrane type gas-water or oil-water separator design.
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Large scale generation of micro-droplet array by vapor condensation on Mesh Screen piece
Scientific Reports, 2017Co-Authors: Jian Xie, Xiaotian He, Jinliang Xu, Qi LiuAbstract:We developed a novel micro-droplet array system, which is based on the distinct three dimensional Mesh Screen structure and sintering and oxidation induced thermal-fluid performance. Mesh Screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more "hydrophilic" than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the Mesh Screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.
Xiaotian He - One of the best experts on this subject based on the ideXlab platform.
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Water drop impacts on a single-layer of Mesh Screen membrane: Effect of water hammer pressure and advancing contact angles
Experimental Thermal and Fluid Science, 2017Co-Authors: Jinliang Xu, Xiaotian He, Yu Cheng, Jian Xie, Qi LiuAbstract:Mesh Screen membrane is a functional material for gas-water or oil-water separation. If a water drop impacts on the membrane at a sufficiently high velocity, a critical condition at which daughter droplets are generated and fall down below the membrane occurs, under which the separator is failure. The objective of this paper is to determine the critical condition. Six Mesh Screen membranes are used. The Mesh wire diameter and Mesh pore are on the same-scale (10–100 μm), involving apparent cross sectional area decrease of Mesh pores in the membrane depth direction. Thus, drop impacting on the membrane yields significant liquid compression in ∼μs timescale to cause additional water hammer pressure. The analysis shows that the liquid compression is related to the number of Mesh pores within drop project area (N). The water hammer pressure relative to dynamic pressure is found to be raised with N. The drop impacting process is governed by the dynamic pressure together with the additional water hammer pressure competed with the maximum capillary pressure at the throat location of the Mesh pore. The modified Weber number −Wew/cos(θA) was correlated with N in a single curve to predict the critical condition for droplet breakthrough, where Wewis characterized by the Mesh pore width and cos(θA) reflects the advancing contact angle effect. This paper is useful for membrane type gas-water or oil-water separator design.
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Large scale generation of micro-droplet array by vapor condensation on Mesh Screen piece
Scientific Reports, 2017Co-Authors: Jian Xie, Xiaotian He, Jinliang Xu, Qi LiuAbstract:We developed a novel micro-droplet array system, which is based on the distinct three dimensional Mesh Screen structure and sintering and oxidation induced thermal-fluid performance. Mesh Screen was sintered on a copper substrate by bonding the two components. Non-uniform residue stress is generated along weft wires, with larger stress on weft wire top location than elsewhere. Oxidation of the sintered package forms micro pits with few nanograsses on weft wire top location, due to the stress corrosion mechanism. Nanograsses grow elsewhere to show hydrophobic behavior. Thus, surface-energy-gradient weft wires are formed. Cooling the structure in a wet air environment nucleates water droplets on weft wire top location, which is more "hydrophilic" than elsewhere. Droplet size is well controlled by substrate temperature, air humidity and cooling time. Because warp wires do not contact copper substrate and there is a larger conductive thermal resistance between warp wire and weft wire, warp wires contribute less to condensation but function as supporting structure. The surface energy analysis of drops along weft wires explains why droplet array can be generated on the Mesh Screen piece. Because the commercial material is used, the droplet system is cost effective and can be used for large scale utilization.