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典型及衍生激波针构型的减阻降热流动特性
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作者 何坤 袁化成 《航空动力学报》 EI CAS CSCD 北大核心 2024年第4期52-64,共13页
为探索激波针对超声速钝头飞行器进行减阻降热时的更优衍生构型,采用数值模拟方法对3种典型单扰流物构型、6种双扰流物构型、两类多扰流物构型和钝锥型激波针的流动特性进行了研究,认为加装激波针后的几何本质相当于“镂空式”的锥型钝... 为探索激波针对超声速钝头飞行器进行减阻降热时的更优衍生构型,采用数值模拟方法对3种典型单扰流物构型、6种双扰流物构型、两类多扰流物构型和钝锥型激波针的流动特性进行了研究,认为加装激波针后的几何本质相当于“镂空式”的锥型钝头体。模拟结果显示:激波针头部扰流物相对直径较大时,减阻率随激波针相对长度的变化曲线没有明显的峰值点,而是存在一个变动幅度很小的峰值段,且相对直径在0.3~0.4左右时减阻效果最佳;典型激波针的最大减阻率约为50%,采用双扰流物构型时略有提升;中部增加多个扰流物时减阻率随扰流物数量增多而增大,最大减阻率超过60%,但气动加热问题较严重。相比而言,钝锥型激波针减阻降温的综合性能最好,最大减阻率可达60%左右,降温率约为7%。 展开更多
关键词 激波针 衍生构型 超声速 减阻降热 流动特性
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Theoretical studies on phosphoraniminato derivatives of Keggin-type polyoxometalates [PW_(11)O_(39){M^VNPPh_3}]^(3-)(M = Fe,Ru):Electronic structures and bonding features
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作者 LIU ChunGuang GUAN XiaoHui SU ZhongMin 《Science China Chemistry》 SCIE EI CAS 2012年第9期1910-1915,共6页
Transition metal phosphoraniminato derivatives of Keggin-type polyoxometalates(POMs) are important intermediates in N-transfer reactions.Density functional theory(DFT) has been employed to calculate the electronic str... Transition metal phosphoraniminato derivatives of Keggin-type polyoxometalates(POMs) are important intermediates in N-transfer reactions.Density functional theory(DFT) has been employed to calculate the electronic structures,bonding features and redox properties of the iron and ruthenium phosphoraniminato derivatives of Keggin-type POMs,[PW11O39{MVNPPh3}] 3-(M = Fe,Ru).Our DFT calculations show that both anions have the same qualitative M-N single bond features.However,the calculations predict that the FeN system possesses a lower energy and more accessible metalnitrogen antibonding orbital than the RuN system.This results in a greater weakening of the Fe-N bond in the reduction process,and thus enhances its N-transfer reactivity. 展开更多
关键词 density functional theory POLYOXOMETALATE N-transfer electronic structure bonding feature
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