Hypersonic vehicles subjected to strong aerodynamic forces and serious aerodynamic heating require more stringent design for an infrared window. In this paper, a finite element analysis is used to present the distribu...Hypersonic vehicles subjected to strong aerodynamic forces and serious aerodynamic heating require more stringent design for an infrared window. In this paper, a finite element analysis is used to present the distributions of thermal and stress fields in the infrared window for hypersonic vehicles based on flowfield studies. A theoretical guidance is provided to evaluate the influence of aerodynamic heating and forces on infrared window materials. The aerodynamic heat flux from Mach 3 to Mach 6 flight at an altitude of 15 km in a standard atmosphere is obtained through flowfield analysis. The thermal and stress responses are then investigated under constant heat transfer coefficient boundary conditions for different Mach numbers. The numerical results show that the maximum stress is higher than the material strength at Mach 6, which means a failure of the material may occur. The maximum stress and temperatures are lower than the material strength and melting point under other conditions, so the material is safe.展开更多
低对称性二维材料是一类晶格对称操作少,纵向仅有原子级厚度的新型纳米材料。在二维过渡金属硫族化合物(Transition metal dichalcogenides,TMDs)体系中,1T’-MoTe_(2)、1T’-WTe_(2)、1T’-ReS_(2)和1T’-ReSe_(2)是典型低对称性成员...低对称性二维材料是一类晶格对称操作少,纵向仅有原子级厚度的新型纳米材料。在二维过渡金属硫族化合物(Transition metal dichalcogenides,TMDs)体系中,1T’-MoTe_(2)、1T’-WTe_(2)、1T’-ReS_(2)和1T’-ReSe_(2)是典型低对称性成员。独特的晶格对称性为它们带来了丰富的各向异性理化性质,因而在微纳光子学、触觉传感器、各向异性逻辑器件等领域具有特殊应用前景。低对称性二维TMDs材料的基础研究和应用开发依赖于对这类材料的高质量、大尺寸、稳定制备。本文以这4类材料为典型,首先按金属前驱体进行分类,综述了近年来有关低对称性二维TMDs材料的化学气相沉积(Chemical vapor deposition,CVD)制备方法;其次,针对制备过程中1T’-MoTe_(2)容易发生相转变,1T’-ReS_(2)、1T’-ReSe_(2)与基底间相互作用力弱等特点,介绍了1T’-MoTe_(2)制备过程中的相调控机制,以及1T’-ReS_(2)、1T’-ReSe_(2)制备过程中的基底工程研究;最后,本文对低对称性二维TMDs材料未来的挑战与机遇进行了展望。展开更多
基金Project supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China （No. 51121004）, and the Fundamental Research Funds for the Central Universities （No. HIT.BRETIV.201315）, China
文摘Hypersonic vehicles subjected to strong aerodynamic forces and serious aerodynamic heating require more stringent design for an infrared window. In this paper, a finite element analysis is used to present the distributions of thermal and stress fields in the infrared window for hypersonic vehicles based on flowfield studies. A theoretical guidance is provided to evaluate the influence of aerodynamic heating and forces on infrared window materials. The aerodynamic heat flux from Mach 3 to Mach 6 flight at an altitude of 15 km in a standard atmosphere is obtained through flowfield analysis. The thermal and stress responses are then investigated under constant heat transfer coefficient boundary conditions for different Mach numbers. The numerical results show that the maximum stress is higher than the material strength at Mach 6, which means a failure of the material may occur. The maximum stress and temperatures are lower than the material strength and melting point under other conditions, so the material is safe.
文摘低对称性二维材料是一类晶格对称操作少,纵向仅有原子级厚度的新型纳米材料。在二维过渡金属硫族化合物(Transition metal dichalcogenides,TMDs)体系中,1T’-MoTe_(2)、1T’-WTe_(2)、1T’-ReS_(2)和1T’-ReSe_(2)是典型低对称性成员。独特的晶格对称性为它们带来了丰富的各向异性理化性质,因而在微纳光子学、触觉传感器、各向异性逻辑器件等领域具有特殊应用前景。低对称性二维TMDs材料的基础研究和应用开发依赖于对这类材料的高质量、大尺寸、稳定制备。本文以这4类材料为典型,首先按金属前驱体进行分类,综述了近年来有关低对称性二维TMDs材料的化学气相沉积(Chemical vapor deposition,CVD)制备方法;其次,针对制备过程中1T’-MoTe_(2)容易发生相转变,1T’-ReS_(2)、1T’-ReSe_(2)与基底间相互作用力弱等特点,介绍了1T’-MoTe_(2)制备过程中的相调控机制,以及1T’-ReS_(2)、1T’-ReSe_(2)制备过程中的基底工程研究;最后,本文对低对称性二维TMDs材料未来的挑战与机遇进行了展望。
