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geometric effects of fuel regression rate in hybrid rocket motors

Science China(Technological Sciences) 2016年第5期59卷 807-813页

作者： CAI GuoBiao ZHANG YuanJun WANG PengFei HUI Tian ZHAO Sheng YU NanJia School of Astronautics Beihang University Beijing 100191 China Beijing Institute of Aerospace Systems Engineering Beijing 100076 China

The geometric configuration of the solid fuel is a key parameter affecting the fuel regression rate in hybrid rocket motors. In this paper, a semi-empirical regression rate model is developed to investigate the geometric effect on the fuel regression rate by incorporating the hydraulic diameter into the classical model. The semi-empirical model indicates that the fuel regression rate decreases with increasing hydraulic diameter and is proportional to dh?0.2 when convective heat transfer is dominant. Then a numerical model considering turbulence, combustion, solid fuel pyrolysis, and a solid–gas coupling model is established to further investigate the geometric effect. Eight motors with different solid fuel grains are simulated, and four methods of scaling the regression rate between different solid fuel grains are compared. The results indicate that the solid fuel regression rates are approximate the same when the hydraulic diameters are equal. The numerical results verify the accuracy of the semi-empirical model.

关键词： geometric effect regression rate hydraulic diameter hybrid rocket motor

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Synthesis of linear and V-shaped oligo(phenylene ethynylene) derivatives:geometric effects on photophysical properties

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Chinese Chemical Letters 2010年第1期21卷 97-100页

作者： Yuan, Si Chun Han, Shu Liang Ge, Xing Wang, Hui Chuan China Agr Univ Fundamental Sci Dept Beijing 102206 Peoples R China Peking Univ Coll Chem Minist Educ Key Lab Bioorgan Chem & Mol Engn Beijing 100871 Peoples R China

A series of linear and V-shaped oligo(phenylene ethynylene) derivatives 1-3 were synthesized through sequent Sonogashira coupling and propargyl alcohol deprotection reaction in high *** alkoxy chains(i.e.,n-hexyloxy groups) were introduced to assure good solubility of compounds 1-3 in common *** photophysical properties of 1-3 in solution depend strongly on the geometries of these compounds.

关键词： Sonogashira coupling Oligo(phenylene ethynylene) derivatives geometric effect Photophysical property

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Asymmetric dynamic behaviors of magnetic domain wall in trapezoid-cross-section nanostrip

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Chinese Physics B 2020年第9期29卷 518-522页

作者： Xiao-Ping Ma Hong-Guang Piao Lei Yang Dong-Hyun Kim Chun-Yeol You Liqing Pan Research Institute for Magnetoelectric&Weak Magnetic-field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Department of Physics Chungbuk National UniversityCheongju 28644ChungbukRepublic of Korea Department of Emerging Materials Science Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea

Field-driven magnetic domain wall propagation in ferromagnetic nanostrips with trapezoidal cross section has been systematically investigated by means of micromagnetic simulation. Asymmetric dynamic behaviors of domain wall, depending on the propagation direction, were observed under an external magnetic field. When the domain walls propagate in the opposite direction along the long axis of the nanostrip, the Walker breakdown fields as well as the average velocities are different. The asymmetric landscape of demagnetization energies, which arises from the trapezoidal geometry, is the main origin of the asymmetric propagation behavior. Furthermore, a trapezoid-cross-section nanostrip will become a nanotube if it is rolled artificially along its long axis, and thus a two-dimensional transverse domain wall will become a three-dimensional one. Interestingly, it is found that the asymmetric behaviors observed in two-dimensional nanostrips with trapezoidal cross section are similar with some dynamic properties occurring in three-dimensional nanotubes.

关键词： ferromagnetic nanowire magnetic domain wall geometric effect asymmetric Walker breakdown

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