Effect of P impurity on mechanical properties of NiAl Σ5 grain boundary:From perspectives of stress and energy

In this paper,we employ the first-principle total energy method to investigate the effect of P impurity on mechanical properties of NiA1 grain boundary(GB).According to"energy",the segregation of P atom in NiA1E5 GB reduces the cleavage energy and embrittlement potential,demonstrating that P impurity embrittles NiA1E5 GB.The first-principle computational tensile test is conducted to determine the theoretical tensile strength of NiA1E5 GB.It is demonstrated that the maximum idea/tensile strength of NiA1E5 GB with P atom segregation is 144.5 GPa,which is lower than that of the pure NiA1E5 GB(164.7 GPa).It is indicated that the segregation of P weakens the theoretical strength of NiA1E5 GB.The analysis of atomic configuration shows that the GB fracture is caused by the interfacial bond breaking.Moreover,P is identified to weaken the interactions between A1-A1 bonds and enhance Ni-Ni bonds.

非平衡等离子体点火助燃的研究进展

从等离子体点火助燃燃烧实验、等离子体助燃的先进激光诊断和等离子体助燃机理三个方面进行概述,总结近些年来国内外对非平衡等离子体点火助燃研究的主要成果。等离子体辅助点火燃烧的最新进展有:辅助冷焰进行的燃烧学基础研究,辅助低热值燃料以及氨等的相关实验研究,等离子体强化贫燃火焰稳定性的研究,混合不同类型放电等离子体点火助燃的仿真计算以及等离子体助燃仿真新模型的建立等。认为在等离子体辅助点火燃烧技术的研究仍应以实验研究为主,积累大量实验数据和经验以支撑进一步的研发和应用;并且在实验中,应多结合不同等离子体以及不同类型等离子体的特点,充分利用其优点,使用混合放电最大化其作用效果。

预混火焰诱导里克管热声振荡实验

为了探究热声振荡现象中各物理量的变化规律,采用单端可调谐激光吸收光谱技术对火焰的温度进行了测量,测量频率为5 kHz,揭示了热声振荡中温度的变化规律。在里克管中,温度以大约230 Hz的频率规律性变化,变化频率与里克管的本征频率接近。里克管出口处的静压监测表明静压与温度在同一频率变化。此外,采用高速相机对火焰化学自发光进行了测量,火焰化学发光强度及发光面积在静压的影响下,也在周期性波动。温度、静压、化学发光强度三者波动频率保持一致。