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Corner Flow Control in High Through-Flow Axial Commercial Fan/Booster Using Blade 3-D Optimization

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Journal of Thermal Science 2012年第1期21卷 32-41页

作者： Fang Zhu Donghai Jin Xingmin Gui Aeroengine numerical simulation Research Center Beihang University Beijing China

This study is aimed at using blade 3-D optimization to control corner flows in the high through-flow fan/booster of a high bypass ratio commercial turbofan engine. Two kinds of blade 3-D optimization, end-bending and bow, are focused on. On account of the respective operation mode and environment, the approach to 3-D aerodynamic modeling of rotor blades is different from stator vanes. Based on the understanding of the mechanism of the corner flow and the consideration of intensity problem for rotors, this paper uses a variety of blade 3-D optimization approaches, such as loading distribution optimization, perturbation of departure angles and stacking-axis manipulation, which are suitable for rotors and stators respectively. The obtained 3-D blades and vanes can improve the corner flow features by end-bending and bow effects. The results of this study show that flows in corners of the fan/booster, such as the fan hub region, the tip and hub of the vanes of the booster, are very complex and dominated by 3-D effects. The secondary flows there are found to have a strong detrimental effect on the compressor performance. The effects of both end-bending and bow can improve the flow separation in corners, but the specific ways they work and application scope are somewhat different. Redesigning the blades via blade 3-D optimization to control the corner flow has effectively reduced the loss generation and improved the stall margin by a large amount.

关键词： corner flow control fan/booster blade 3-D optimization end-bending bow

Modeling and numerical Investigation of the Inlet Circumferential Fluctuationsof Swept and Bowed Blades

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Journal of Thermal Science 2017年第1期26卷 1-10页

作者： TANG Mingzhi JIN Donghai GUI Xingmin Aeroengine numerical simulation Research Center Beihang University Beijing China.

The circumferential fluctuation (CF) source terms induced by the inviscid blade force can affect the inlet distribution of flow parameters and radial equilibrium of swept and bowed blades. However, these phenomena cannot be adequately described by throughflow methods based on the axisymmetric assumption. A transport model for the CF stresses is proposed and correlated to the distribution of circulation to reflect the effect of the inviscid blade force. To investigate the effect of the inlet CFs on swept and bowed blades, the model is integrated into a throughflow model and applied to a series of cascades with different sweep and bow angles. For swept cascades, the CF source terms change the distributions of incidence angles, as well as the radial equilibrium at the inlet of the blade passage. And the influence is enhanced as the absolute value of the sweep angle increases. For bowed cascades, the distributions of incidence angles are also altered. For both cases, the model can offer a good prediction of the inlet CF source terms, and prove to exert a better prediction of blade design key parameters such as flow angles. © 2017, Science Press, institute of Engineering Thermophysics, CAS and Springer-Verlag Berlin Heidelberg.

关键词： Condensed matter physics

Optimal Control of Oxygen Concentration in a Magnetic Czochralski Crystal Growth by Response Surface Methodology

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Journal of Materials Science & Technology 2006年第2期22卷 173-178页

作者： Huiping YU Yunkan SUI Jing WANG Fengyi ZHANG Xiaolin DAI numerical simulation Center of Engineering Beijing University of Technology Beijing 100022 China General Research institute for Nonferrous Metals Beijing 100088 China

Concepts and techniques of response surface methodology have been widely applied in many branches of engineering, especially in the chemical and manufacturing areas. This paper presents an application of the methodology in a magnetic crystal Czochralski growth system for single crystal silicon to optimize the oxygen concentration at the crystal growth interface in a cusp magnetic field. The simulation demonstrates that the response surface methodology is a feasible algorithm for the optimization of the Czochralski crystal growth process.

关键词： Czochralski Magnetic field Optimization Response surface methodology

COMBINATION OF GLOBAL AND LOCAL APPROXIMATION SCHEMES FOR HARMONIC MAPS INTO SPHERES

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Journal of Computational Mathematics 2009年第2期27卷 170-183页

作者： Sren Bartels institute for numerical simulation Rheinische Friedrich-Wilhelms-Universitt BonnWegelerstraβe 653115 BonnGermany

It is well understood that a good way to discretize a pointwise length constraint in partial differential equations or variational problems is to impose it at the nodes of a triangulation that defines a lowest order finite element space. This article pursues this approach and discusses the iterative solution of the resulting discrete nonlinear system of equations for a simple model problem which defines harmonic maps into spheres. An iterative scheme that is globally convergent and energy decreasing is combined with a locally rapidly convergent approximation scheme. An explicit example proves that the local approach alone may lead to ill-posed problems; numerical experiments show that it may diverge or lead to highly irregular solutions with large energy if the starting value is not chosen carefully. The combination of the global and local method defines a reliable algorithm that performs very efficiently in practice and provides numerical approximations with low energy.

关键词： Harmonic maps Iterative methods Pointwise constraint

Formation of a disordered region at the grain boundary during migration with He atoms

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Science China(Physics,Mechanics & Astronomy) 2017年第4期60卷 78-81页

作者： Shi Yuan Hu Yi Yu Wei Shi Yuan YuHan Wang XiaoLin Shu GuangHong Lu Department of Physics Beihang University institute of Applied Physics & Computational Mathematics Software Center for High Performance numerical simulation

W is considered a potential candidate as a plasma facing ma- terial for future nuclear fusion devices because of its high melting point, low sputtering rate, and low H or He solubility [1-3]. In a fusion environment, W will be in direct contact with heat flux, H/He particle fluxes, and the irradiation of high-energy neutrons, causing several defects to be generated, which decrease the service life of W materials. The grain boundary （GB）, which is an important type of defect, affects the various physical and mechanical properties of ma- terials. In the nuclear environment, the GB can act as a sink for the defects when the material is under irradiation.

关键词： migration sputtering solubility irradiation melting disordered defects candidate facing causing

The effects of the Dzyaloshinskii-Moriya interaction on the ground-state properties of the XY chain in a transverse field

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Chinese Physics B 2013年第9期22卷 285-291页

作者：钟鸣徐卉刘小贤童培庆 Department of Physics and institute of Theoretical Physics Nanjing Normal University Jiangsu Key Laboratory for numerical simulation of Large Scale Complex Systems Nanjing Normal University

The effects of the Dzyaloshinski-Moriya （DM） interaction on the ground-state properties of the anisotropic XY chain in a transverse field have been studied by means of correlation functions and entanglement. Different from the case without the DM interaction, the excitation spectra ek of this model are not symmetrical in the momentum space and are not always positive. As a result, besides the ferromagnetic （FM） and the paramagnetic （PM） phases, a gapless chiral phase is induced. In the chiral phase, the von Neumann entropy is proportional to log2 L （L is the length of a subchain） with the coefficient A ~ 1/3, which is the same as that of the XY chain in a transverse field without the DM interaction for 7 = 0 and 0 〈 h 〈 1. And in the vicinity of the critical point between the chiral phase and the FM （or PM） phase, the behaviors of the nearest- neighbor concurrence and its derivative are like those for the anisotropy transition.

关键词： Dzyaloshinskii-Moriya interaction the XY chain in a transverse field quantum entanglement,ground-state properties

A first-principles study of the structural and elastic properties of orthorhombic and tetragonal Ca_3Mn_2O_7

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Chinese Physics B 2013年第6期22卷 465-471页

作者：张玮童培庆 Department of Physics Institute of Theoretical PhysicsNanjing Normal University Jiangsu Key Laboratory for numerical simulation of Large Scale Complex Systems Nanjing Normal University

The structural and elastic properties of multiferroic Ca3Mn2O7 with ferroelectric orthorhombic （O-phase） and paraelectric tetragonal structures （T-phase） have been studied by first-principles calculations within the generalized gradient approximation （GGA） and the GGA plus Hubbard U approaches （GGA ＋ U）. The calculated theoretical structures are in good agreement with the experimental values. The T-phase is found to be antiferromagnetic （AFM） and the AFM O-phase is more stable than the T-phase, which also agree with the experiments. On these bases, the single-crystal elastic constants （Cijs） and elastic properties of polycrystalline aggregates are investigated for the two phases. Our elasticity calculations indicate Ca3Mn2O7 is mechanically stable against volume expansions. The AFM O-phase is found to be a ductile material, while the AFM T-phase shows brittle nature and tends to be elastically isotropic. We also investigate the influence of strong correlation effects on the elastic properties, qualitatively consistent results are obtained in a reasonable range of values of U. Finally, the ionicity is discussed by Bader analysis. Our work provides useful guidance for the experimental elasticity measurements of Ca3Mn2O7, and makes the strain energy calculation in multiferroic Ca3Mn2O7 thin films possible.

关键词： elastic constant elastic anisotropy strong correlation effect multiferroic

The invariant of the stiffness filter function with the weight filter function of the power function form

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Acta Mechanica Sinica 2012年第6期28卷 1617-1619页

作者： Zhen Shang Yun-Kang Sui The Centre of numerical simulation for Engineering College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology

Based on the independent, continuous and map- ping （ICM） method and homogenization method, a research model is constructed to propose and deduce a theorem and corollary from the invariant between the weight filter func- tion and the corresponding stiffness filter function of the form of power function. The efficiency in searching for op- timum solution will be raised via the choice of rational filter functions, so the above mentioned results are very important to the further study of structural topology optimization.

关键词： ICM method Filter function Power function Invariant

The ICM method with objective function transformed by variable discrete condition for continuum structure

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Acta Mechanica Sinica 2006年第1期22卷 68-75页

作者： Yunkang Sui Xirong Peng numerical simulation Center for Engineering The College of Mechanical Engineering and Applied Electronics TechnologyBeijing University of TechnologyBeijing 100022

ICM （Independent Continuous Mapping） method can solve topological optimization problems with the minimized weight as the objective and subjected to displacement constraints. To get a clearer topological configuration, by introducing the discrete condition of topological variables and integrating with the original objective, an optimal model with multi-objectives is formulated to make the topological variables approach 0 or 1 as near as possible, and the model reduces the effect of deleting rate on the result. The image-filtering method is employed to eliminate the checkerboard patterns and mesh dependence that occurred in the topology optimization of a continuum structure. The computational efficiency is enhanced through selecting quasi-active displacement constraints and a design region. numerical examples indicate that this algorithm is robust and practicable, though the number of iterations is slightly increased with respect to the original algorithm.

关键词： Structural topological optimization ICM method Checkerboard patterns Mesh dependence Thedeleting rate