Hexagonal trumpet-like sodium hexafluorosilicate （SFS） flowers, grown on an ordered porous polystyrene film （OPPF）, were prepared via a synchronous dissolution/regrowth process. Their formation process can be divi...Hexagonal trumpet-like sodium hexafluorosilicate （SFS） flowers, grown on an ordered porous polystyrene film （OPPF）, were prepared via a synchronous dissolution/regrowth process. Their formation process can be divided into several steps： first, the dissolution of the silica spheres induced the crystallization of SFS onto the OPPF; second, some pores emerged on the closely packed bumps when being blown by the SiF4 gas; third, when the crystal was blown by continuous gas from the pores, the span of the top became larger than that of the bottom.展开更多
Adaptive composites are widely employed in various hydraulic and marine applications,such as propulsors,turbines,and renewable energy-harvesting devices.This study investigates vortex-induced vibrations(VIV)in carbon ...Adaptive composites are widely employed in various hydraulic and marine applications,such as propulsors,turbines,and renewable energy-harvesting devices.This study investigates vortex-induced vibrations(VIV)in carbon fiber-reinforced plastic(CFRP)hydrofoils with different ply angles,focusing on the lock-in phenomenon.A multi-field synchronous measurement system was developed to simultaneously capture vortex dynamics and structural vibrations.The vibration spectrum under various flow velocities revealed distinct lock-in behaviors for the CFRP hydrofoils with different ply angles.The hydrofoil with 45°ply angle exhibited a“partial lock-in”behavior,characterized by dual lock-in peaks during secondary frequency lock-in.In contrast,the hydrofoil with−45°ply angle displayed a“double lock-in”phenomenon,marked by the simultaneous occurrence of two lock-in events.To elucidate the underlying mechanism,dynamic mode decomposition(DMD)was applied to identify the dominant vortex structures and their frequency characteristics in the wake during“partial lock-in”.This work provides methodological insights and engineering paradigms for the vibration suppression design of next-generation high-performance composite hydraulic equipment.展开更多
Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidiz...Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidizing gas flow,the HfC coating forms a high-melting-point heterogeneous oxide layer,significantly delaying oxidation of the underlying material and preserving the structural integrity of the C/C composites[4].展开更多
基金supported by the National Natural Science Foundation of China(Nos.51273056,21202091,5121010502,21074031)Postdoctoral Science Foundation Projects of China(No.2013M531008)Heilongjiang Provincial Department of Education(No.12521398)
文摘Hexagonal trumpet-like sodium hexafluorosilicate （SFS） flowers, grown on an ordered porous polystyrene film （OPPF）, were prepared via a synchronous dissolution/regrowth process. Their formation process can be divided into several steps： first, the dissolution of the silica spheres induced the crystallization of SFS onto the OPPF; second, some pores emerged on the closely packed bumps when being blown by the SiF4 gas; third, when the crystal was blown by continuous gas from the pores, the span of the top became larger than that of the bottom.
文摘Adaptive composites are widely employed in various hydraulic and marine applications,such as propulsors,turbines,and renewable energy-harvesting devices.This study investigates vortex-induced vibrations(VIV)in carbon fiber-reinforced plastic(CFRP)hydrofoils with different ply angles,focusing on the lock-in phenomenon.A multi-field synchronous measurement system was developed to simultaneously capture vortex dynamics and structural vibrations.The vibration spectrum under various flow velocities revealed distinct lock-in behaviors for the CFRP hydrofoils with different ply angles.The hydrofoil with 45°ply angle exhibited a“partial lock-in”behavior,characterized by dual lock-in peaks during secondary frequency lock-in.In contrast,the hydrofoil with−45°ply angle displayed a“double lock-in”phenomenon,marked by the simultaneous occurrence of two lock-in events.To elucidate the underlying mechanism,dynamic mode decomposition(DMD)was applied to identify the dominant vortex structures and their frequency characteristics in the wake during“partial lock-in”.This work provides methodological insights and engineering paradigms for the vibration suppression design of next-generation high-performance composite hydraulic equipment.
基金supported by the National Natural Science Foundation of China(Grant Nos.52302115,52231004)。
文摘Hafnium carbide(HfC)serves as a critical ablation-resistant coating for C/C composites used on the wing leading edges of high-speed vehicles during atmospheric re-entry[1-3].Under the action of high-temperature,oxidizing gas flow,the HfC coating forms a high-melting-point heterogeneous oxide layer,significantly delaying oxidation of the underlying material and preserving the structural integrity of the C/C composites[4].
