The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Rainer Gadow - One of the best experts on this subject based on the ideXlab platform.
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introduction to high velocity suspension flame spraying hvsfs
Journal of Thermal Spray Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:High-velocity suspension flame spraying (HVSFS) has been developed to thermally spray suspensions containing micron, submicron, and nanoparticles with Hypersonic Speed. For this purpose, the suspension is introduced directly into the combustion chamber of a modified HVOF torch. The aim in mind is to achieve dense coatings with a refined microstructure. Especially from nanostructured coatings superior physical properties are expected for many potential applications. Direct spraying of suspensions offers flexibility in combining and processing different materials. It is a cost-saving process and allows the allocation of entirely new application fields. The paper gives an overview of the HVSFS spray method and will present some actual results that have been achieved by spraying the nanooxide ceramic materials Al2O3, TiO2, 3YSZ, and Cr2O3.
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new results in high velocity suspension flame spraying hvsfs
Surface & Coatings Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:Abstract High Velocity Suspension Flame Spraying (HVSFS) is a new approach for spraying micron, submicron and nanoparticles with Hypersonic Speed by feeding a suspension directly into the combustion chamber of a HVOF torch. The aim in mind is to achieve dense coatings with an improved microstructure — probably reaching the nanoscale, from which superior physical properties are expected. Compared to the alternative approach, i.e.. using agglomerated (nano- and micron-sized) powders, direct spraying of suspensions shows much higher flexibility in combining and processing different materials and is far less expensive. Several suspensions consisting of an organic solvent and a solid phase consisting of a micron or a nanopowder have been prepared and HVSFS sprayed. Suspensions containing oxide nanopowders of titanium oxide (n-TiO 2 ), chromium (III) oxide (n-Cr 2 O 3 ), yttrium stabilized zirconia (n-YSZ) and a n-hydroxyapatite (n-HAP). Furthermore two suspensions containing glass powders (grain size 2–3 μμm after milling) were also sprayed: a Zr–Al–Si containing glass (FOA) and a phosphor containing bioglass (AW). HVSFS coatings were characterized regarding their phase composition and microstructure. Mechanical and tribological properties are compared with standard coatings produced by APS and HVOF.
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high velocity suspension flame spraying hvsfs a new approach for spraying nanoparticles with Hypersonic Speed
Surface & Coatings Technology, 2006Co-Authors: Andreas Killinger, Melanie Kuhn, Rainer GadowAbstract:The fabrication of nanostructured coatings by means of thermal spray techniques is a challenging approach with new applications in mind. However, it requires the processing of very fine-grained powders with a grain size in the nanoscale. As nano- and submicrometer powders cannot be processed using mechanical powder feeders, new concepts have to be developed. Among these, suspension spraying is one of the most promising. High-velocity suspension flame spraying (HVSFS) is a new approach to spray micron, submicron or nanoparticles with Hypersonic Speed with the aim to form thin and dense coating layers. For this purpose, the powder is dispersed in aqueous or organic solvent and fed axially into the combustion chamber of a modified High-Velocity Oxyfuel (HVOF) spray torch. Several suspension feeder concepts were tested to ensure a constant flow of the suspension and, thus, a stable spray process. Different oxide materials were processed in form of a suspension containing submicrometer- or nanosized powders consisting of alumina, titania and yttrium stabilized zirconia (YSZ). The paper gives an introduction to HVSFS technology and will present first experimental results.
Andreas Killinger - One of the best experts on this subject based on the ideXlab platform.
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introduction to high velocity suspension flame spraying hvsfs
Journal of Thermal Spray Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:High-velocity suspension flame spraying (HVSFS) has been developed to thermally spray suspensions containing micron, submicron, and nanoparticles with Hypersonic Speed. For this purpose, the suspension is introduced directly into the combustion chamber of a modified HVOF torch. The aim in mind is to achieve dense coatings with a refined microstructure. Especially from nanostructured coatings superior physical properties are expected for many potential applications. Direct spraying of suspensions offers flexibility in combining and processing different materials. It is a cost-saving process and allows the allocation of entirely new application fields. The paper gives an overview of the HVSFS spray method and will present some actual results that have been achieved by spraying the nanooxide ceramic materials Al2O3, TiO2, 3YSZ, and Cr2O3.
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new results in high velocity suspension flame spraying hvsfs
Surface & Coatings Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:Abstract High Velocity Suspension Flame Spraying (HVSFS) is a new approach for spraying micron, submicron and nanoparticles with Hypersonic Speed by feeding a suspension directly into the combustion chamber of a HVOF torch. The aim in mind is to achieve dense coatings with an improved microstructure — probably reaching the nanoscale, from which superior physical properties are expected. Compared to the alternative approach, i.e.. using agglomerated (nano- and micron-sized) powders, direct spraying of suspensions shows much higher flexibility in combining and processing different materials and is far less expensive. Several suspensions consisting of an organic solvent and a solid phase consisting of a micron or a nanopowder have been prepared and HVSFS sprayed. Suspensions containing oxide nanopowders of titanium oxide (n-TiO 2 ), chromium (III) oxide (n-Cr 2 O 3 ), yttrium stabilized zirconia (n-YSZ) and a n-hydroxyapatite (n-HAP). Furthermore two suspensions containing glass powders (grain size 2–3 μμm after milling) were also sprayed: a Zr–Al–Si containing glass (FOA) and a phosphor containing bioglass (AW). HVSFS coatings were characterized regarding their phase composition and microstructure. Mechanical and tribological properties are compared with standard coatings produced by APS and HVOF.
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high velocity suspension flame spraying hvsfs a new approach for spraying nanoparticles with Hypersonic Speed
Surface & Coatings Technology, 2006Co-Authors: Andreas Killinger, Melanie Kuhn, Rainer GadowAbstract:The fabrication of nanostructured coatings by means of thermal spray techniques is a challenging approach with new applications in mind. However, it requires the processing of very fine-grained powders with a grain size in the nanoscale. As nano- and submicrometer powders cannot be processed using mechanical powder feeders, new concepts have to be developed. Among these, suspension spraying is one of the most promising. High-velocity suspension flame spraying (HVSFS) is a new approach to spray micron, submicron or nanoparticles with Hypersonic Speed with the aim to form thin and dense coating layers. For this purpose, the powder is dispersed in aqueous or organic solvent and fed axially into the combustion chamber of a modified High-Velocity Oxyfuel (HVOF) spray torch. Several suspension feeder concepts were tested to ensure a constant flow of the suspension and, thus, a stable spray process. Different oxide materials were processed in form of a suspension containing submicrometer- or nanosized powders consisting of alumina, titania and yttrium stabilized zirconia (YSZ). The paper gives an introduction to HVSFS technology and will present first experimental results.
J Rauch - One of the best experts on this subject based on the ideXlab platform.
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introduction to high velocity suspension flame spraying hvsfs
Journal of Thermal Spray Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:High-velocity suspension flame spraying (HVSFS) has been developed to thermally spray suspensions containing micron, submicron, and nanoparticles with Hypersonic Speed. For this purpose, the suspension is introduced directly into the combustion chamber of a modified HVOF torch. The aim in mind is to achieve dense coatings with a refined microstructure. Especially from nanostructured coatings superior physical properties are expected for many potential applications. Direct spraying of suspensions offers flexibility in combining and processing different materials. It is a cost-saving process and allows the allocation of entirely new application fields. The paper gives an overview of the HVSFS spray method and will present some actual results that have been achieved by spraying the nanooxide ceramic materials Al2O3, TiO2, 3YSZ, and Cr2O3.
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new results in high velocity suspension flame spraying hvsfs
Surface & Coatings Technology, 2008Co-Authors: Rainer Gadow, Andreas Killinger, J RauchAbstract:Abstract High Velocity Suspension Flame Spraying (HVSFS) is a new approach for spraying micron, submicron and nanoparticles with Hypersonic Speed by feeding a suspension directly into the combustion chamber of a HVOF torch. The aim in mind is to achieve dense coatings with an improved microstructure — probably reaching the nanoscale, from which superior physical properties are expected. Compared to the alternative approach, i.e.. using agglomerated (nano- and micron-sized) powders, direct spraying of suspensions shows much higher flexibility in combining and processing different materials and is far less expensive. Several suspensions consisting of an organic solvent and a solid phase consisting of a micron or a nanopowder have been prepared and HVSFS sprayed. Suspensions containing oxide nanopowders of titanium oxide (n-TiO 2 ), chromium (III) oxide (n-Cr 2 O 3 ), yttrium stabilized zirconia (n-YSZ) and a n-hydroxyapatite (n-HAP). Furthermore two suspensions containing glass powders (grain size 2–3 μμm after milling) were also sprayed: a Zr–Al–Si containing glass (FOA) and a phosphor containing bioglass (AW). HVSFS coatings were characterized regarding their phase composition and microstructure. Mechanical and tribological properties are compared with standard coatings produced by APS and HVOF.
Yoshiaki Nakamura - One of the best experts on this subject based on the ideXlab platform.
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Experimental Analysis of TSTO Aerodynamic Interactions Based on Oil Flow Patterns at Hypersonic Speed
2016Co-Authors: Hiroshi Ozawa, Koichi Mori, Yoshiaki NakamuraAbstract:A small crack on body surface led to a tragic accident in 2003, which is the Columbia accident. During the shuttle’s re-entry, high temperature gas penetrated crack on leading-edge of the left wing and melted the aluminum structure, finally the Columbia blew up. Since early times, there are many fundamental studies about simple cavity-flow in Hypersonic Speed, and then, which becomes more active as a result of its disaster. In practical situation, no one can notify where the crack is formed during Hypersonic flight, then worst of all, it may locates at most severe area such as Shock/Shock Interaction (SSI) and Shock/Boundary Layer Interaction (SBLI) point. In this study, pressure distributions and aerodynamic interaction flow-fields were investigated for No-Crack and With-Crack TSTO models at Hypersonic Speed (M∞=8.1). As a result, the flow-field around TSTO models was made clear, then the aerodynamic interaction flow-fields and the pressure distributions around crack are quite different between No-Crack and With-Crack TSTO at h/D=0.44. With-Crack TSTO produces a large separation region on the delta wing, which leads SSI in front of orbiter nose, and two peaks of pressure on the crack floor, which locates a reattachment point and a recompression region. These peak pressure values are almost the same as a value of the SBLI point in the case of No-Crack TSTO. Nomenclature D = diameter of orbiter, 23mm h = clearance between orbiter and booster L = chord length of booster, 200mm Λ = swept angle of booster, 75deg M = Mach number p = model surface pressure [Pa] T = temperature [K] Re = unit Reynolds number, 4.2×106 [m-1] x, y = coordinates [mm] φ = angle from orbiter nose in the symmetry plane d = length of square crack C = depth of square crack Subscripts 0 = stagnation point value ∞ = freestream value ref = reference value I
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Unsteady Aerodynamic Interaction between Two Bodies at Hypersonic Speed
TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2010Co-Authors: Hiroshi Ozawa, Keiichi Kitamura, Katsuhisa Hanai, Koichi Mori, Yoshiaki NakamuraAbstract:This paper presents experimental results of unsteady aerodynamic interactions including Shock/Shock Interaction (SSI) and Shock/Boundary Layer Interaction (SBLI) between two bodies at Hypersonic Speed. These interactions can be seen in space vehicles consisting of multi-bodies, such as a TSTO, or at a scramjet engine inlet. The present study considers the effect of a flat plate below the SSI where a boundary-layer is developed on the plate surface. More specifically, the interacted flow for a combination of a flat plate (FP) and a hemi-circular cylinder (HCC) is examined at a Hypersonic Speed (M∞=8.1); the distributions of surface pressure and heat transfer rate are measured. To obtain various SSI patterns, the clearance between two bodies (FP and HCC) is changed. Results show that unsteadiness at the SSI point causes a feedback loop between the two bodies; a jet flow impinges on the FP, the effect of which propagates upstream where the jet impinges on the FP, and the aerodynamic and aerothermodynamic loads reach their maxima. Finally, we found that the feedback loop can be destroyed by installing a fence on the FP to reduce unsteadiness of flow field.
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Experimental Analysis of TSTO Aerodynamic Interactions Based on Oil Flow Patterns at Hypersonic Speed
47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009Co-Authors: Hiroshi Ozawa, Koichi Mori, Yoshiaki NakamuraAbstract:A small crack on body surface led to a tragic accident in 2003, which is the Columbia accident. During the shuttle’s re-entry, high temperature gas penetrated crack on leadingedge of the left wing and melted the aluminum structure, finally the Columbia blew up. Since early times, there are many fundamental studies about simple cavity-flow in Hypersonic Speed, and then, which becomes more active as a result of its disaster. In practical situation, no one can notify where the crack is formed during Hypersonic flight, then worst of all, it may locates at most severe area such as Shock/Shock Interaction (SSI) and Shock/Boundary Layer Interaction (SBLI) point. In this study, pressure distributions and aerodynamic interaction flow-fields were investigated for No-Crack and With-Crack TSTO models at Hypersonic Speed (M∞=8.1). As a result, the flow-field around TSTO models was made clear, then the aerodynamic interaction flow-fields and the pressure distributions around crack are quite different between No-Crack and With-Crack TSTO at h/D=0.44. With-Crack TSTO produces a large separation region on the delta wing, which leads SSI in front of orbiter nose, and two peaks of pressure on the crack floor, which locates a reattachment point and a recompression region. These peak pressure values are almost the same as a value of the SBLI point in the case of No-Crack TSTO.
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the role of vortices in side jet blunt body interaction at Hypersonic Speed
Transactions of The Japan Society for Aeronautical and Space Sciences Space Technology Japan, 2009Co-Authors: Keiichi Kitamura, Koichi Mori, Mohammed Ibrahim, Tetsuya Nakamura, Yoshiaki NakamuraAbstract:A numerical investigation was carried out for a blunt body with a circular sonic air jet normally injected into a Hypersonic flow from the body surface, where the angle of attack was changed up to 40◦. Computed results were compared with the experimental data collected using the shock tunnel of Nagoya University. The aerodynamic interaction due to the jet creates complicated flow fields, which are rather difficult to analyze alone experimentally. The computed results show good agreement with the experimental data with regard to surface pressure distribution and schlieren visualization. It was found that at rather low angles of attack, two vortices, i.e., a separation vortex and a horseshoe vortex, are formed inside the separated boundary layer upstream of the jet. The location of these vortices corresponds to low-pressure regions in the pressure distribution. On the other hand, at a rather high angle of attack, the interaction produces a complex flow field, where vortices have little influence on the pressure distribution. Finally the jet interaction was found to enhance the jet reaction forces by about 35% - 45 % on the body surface, the value of which is close to the experimental data.
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Experimental Analysis of TSTO Aerodynamic Heating Problems at Hypersonic Speed
15th AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 2008Co-Authors: Hiroshi Ozawa, Katsuhisa Hanai, Koichi Mori, Mohammed K. Ibrahim, Yoshiaki NakamuraAbstract:This paper presents experimental results of TSTO (Two-Stage-To-Orbit) aerodynamic heating at Hypersonic Speed. TSTO is a promising space transportation system consisting of two stages, i.e., an orbiter and a booster, and is supposed to fly in a wide Speed range from subsonic to Hypersonic. However, when it flies at Hypersonic Speed, it undergoes severe aerodynamic heating under some conditions. Thus, in order to overcome this crucial problem, researchers are motivated to find how to reduce this heating load. Although there seems to be a lot of factors that could affect the heating, the present work focuses on the effects of TSTO configuration on the heating due to aerodynamic interaction. There are many parameters that influence the heating. In the present study two of these parameters are considered which are; i) the booster configurations and ii) the clearance between the two stages. The flight condition is fixed at a Hypersonic Speed of M∞=8.1. First, as a baseline TSTO configuration, a Hemisphere-Cylinder (HC) is employed as orbiter, and a Delta-Wing (DW) as booster. Then, we used a more practical configuration for the booster, i.e., a Hypersonic-booster-model (HBM), which has a wider spanwise leading edge on the main wing in addition to a pair of fins. For these two models, their aerodynamic interaction flow fields as well as heating distributions have been examined with various clearance. As a result, the peak heat flux on the HC in the case of the HBM was reduced to half of that in the case of the DW. However, they showed a similar trend with regard to the interaction pattern change from shock/shock interaction to shock/boundary-layer interaction, which occurs when the clearance of the two bodies was increased.
Melanie Kuhn - One of the best experts on this subject based on the ideXlab platform.
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high velocity suspension flame spraying hvsfs a new approach for spraying nanoparticles with Hypersonic Speed
Surface & Coatings Technology, 2006Co-Authors: Andreas Killinger, Melanie Kuhn, Rainer GadowAbstract:The fabrication of nanostructured coatings by means of thermal spray techniques is a challenging approach with new applications in mind. However, it requires the processing of very fine-grained powders with a grain size in the nanoscale. As nano- and submicrometer powders cannot be processed using mechanical powder feeders, new concepts have to be developed. Among these, suspension spraying is one of the most promising. High-velocity suspension flame spraying (HVSFS) is a new approach to spray micron, submicron or nanoparticles with Hypersonic Speed with the aim to form thin and dense coating layers. For this purpose, the powder is dispersed in aqueous or organic solvent and fed axially into the combustion chamber of a modified High-Velocity Oxyfuel (HVOF) spray torch. Several suspension feeder concepts were tested to ensure a constant flow of the suspension and, thus, a stable spray process. Different oxide materials were processed in form of a suspension containing submicrometer- or nanosized powders consisting of alumina, titania and yttrium stabilized zirconia (YSZ). The paper gives an introduction to HVSFS technology and will present first experimental results.