This paper presents the results of a numerical study on a supercritical CO2 (SCO2) turboshaft cooling device by considering heat transfer and hydrodynamics. A micro-cooling device with a radius clearance of 50 micron ...
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This paper presents the results of a numerical study on a supercritical CO2 (SCO2) turboshaft cooling device by considering heat transfer and hydrodynamics. A micro-cooling device with a radius clearance of 50 micron and a nozzle diameter of 4 mm was designed and used to investigate the heat transfer characteristics of a micro-spacing impinging and gas film dynamics. Sixteen nozzles (N = 16) are equally spaced around the shaft in single or double rows. Investigations include journal speed- and eccentricity-dependent forward and cross-coupled force coefficients, and the effects of nozzle layouts and mass flow rate on the heat transfer efficiency. Analysis of the correlation coefficient shows that the gas density in the radial clearance is the dominant factor affecting the convective heat transfer performance, while the fluid velocity is a secondary factor. And the cooling efficiency (mass flow utilization rate) at low cooling pressure (p(s) < 0.7 MPa) is significantly greater than that at high cooling pressure (p(s) > 0.7 MP). In addition, considering the structure alone, a dual-row cooler exhibits a higher average Nusselt number, also registers a higher mass flow rate at the same pressure. Once the shaft is heated only one end, the difference in effectiveness between single- and dual-row cooling is not significant, so coolers with a single-row configuration should be preferred. Then, experimental values for the temperature of the heated rotor are provided under specific cooling airflow conditions. Dynamic analysis results show that the force coefficient of the single-row configuration is more dependent on the journal rotation speed and eccentricity ratio, and exhibits a negative direct stiffness coefficient at higher inlet pressure and journal rotation speed. Moreover, cross-coupled terms (stiffness coefficient) generally have a more explicit variation tendency than direct terms, and are more sensitive to changes in shaft speed and eccentricity. Small clearance cool
Graphene and related materials are emerging revolutionary materials due to fascinating stimuli-responsive physiochemical properties having widespread applications in developing advanced nano-systems for detection, dia...
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This paper describes the equivalent thermal conductivity for the hexagonally arranged windings and the correction method for the maximum temperature of the coil from that of the homogeneous unit. A stator with the hom...
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Due to the surface covered by the capillary wick in the high temperature heat pipe, the classical evaporation and condensation model may be difficult to characterize the evaporation process well in the high temperatur...
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The combined influence of mining activities and the underlying terrain gradient has caused significant transformations in the landscape patterns of mining cities. The natural topography being altered by mining operati...
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Modified Condition/Decision Coverage (MC/DC) is a test coverage standard with excellent fault detection capability, which is widely used in testing safety-critical software. Symbolic execution generates test cases aut...
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Rigid origami has great potential in aerospace applications,especially deployable polyhedrons with one degree of freedom(DOF)and flat-foldability,whose types are few to *** this paper,we create a novel foldable cube a...
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Rigid origami has great potential in aerospace applications,especially deployable polyhedrons with one degree of freedom(DOF)and flat-foldability,whose types are few to *** this paper,we create a novel foldable cube and a rhombic dodecahedron by introducing slits and diagonal creases to the surfaces,whose one-DOF rigid and flat-foldable properties are verified by kinematic ***,based on the isohedral quadrilateral transform,we project the creases and slits of the rhombic dodecahedron onto a tetrahedron to obtain a novel foldable tetrahedron that has two flat-foldable motion paths due to the existence of collinear *** the second path,unnecessary creases are removed,and an origami tetrahedron with simplified creases is *** origami tetrahedrons possess a small folded *** analysis reveals that these newly discovered origami polyhedrons are flat-foldable with one DOF,demonstrating favorable application prospects for space architectures and extraterrestrial habitats.
In this paper, a new developed Monte Carlo method code, intended to be used in shielding calculations, will be introduced. This code was developed on the basis of RMC and under the collaboration of the Nuclear Power I...
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We detail a dispersion engineering strategy for microresonators allowing us to generate microcombs in the near-infrared and mid-infrared regimes, and identifying optimal shapes for achieving anomalous dispersion suite...
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Traditional antifouling agents usually have a certain toxic effect on marine environments and non-target *** this study,Dictyophora indusiata polysaccharide(DIP)was applied as a natural antifouling surface modifier to...
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Traditional antifouling agents usually have a certain toxic effect on marine environments and non-target *** this study,Dictyophora indusiata polysaccharide(DIP)was applied as a natural antifouling surface modifier to prepare the surface coating for marine *** DIP coatings were prepared:*** spore polysaccharide(DISP),*** volva polysaccharide(DIVP),and *** embryonic body polysaccharide(DIEP).The antifouling,tribological,and anticorrosion behavior of the coatings were *** revealed that the three kinds of DIP coatings had excellent antifouling properties,which could effectively prevent the adhesion of Chlorella and the attachment of water-based and oily stains on the ***,the coatings showed great mechanical stability and could maintain an extremely low coefficient of friction(COF<0.05)after continuous *** drag reduction rate of the coated surfaces reached 5%,showing a powerful lubrication ***,the DIP coatings presented an outstanding corrosion resistance,where the equivalent circuit impedances were 4-9 orders of magnitude higher than the control *** research showed a promising prospect of surface coating fabrication with DIP for marine devices to achieve the purpose of antifouling and drag reduction.
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