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Fluid-thermal-mechanical Coupled Analysis and Optimized Design of Printed Circuit Heat Exchanger with Airfoil Fins of S-CO_(2) Brayton Cycle

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Journal of thermal Science 2022年第6期31卷 2264-2280页

作者： JIANG Tao LI Mingjia WANG Wenqi LI Dong LIU Zhanbin Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi'an710049China

Printed Circuit Heat Exchanger(PCHE) with high-efficiency and compact structure has great application prospect in the supercritical carbon dioxide(S-CO_(2)) power systems for the next generation of high-temperature concentrated solar and advanced nuclear energy. However, the high operating temperature and pressure require PCHE to maintain good heat transfer performance, as well as reliable mechanical performance at the same time. It is necessary to carry out the fluid-thermal-mechanical coupled analysis of PCHE for the safe and efficient operation of the S-CO_(2) cycle. In this paper, a three-dimensional fluid-structure coupled numerical model was established to study the fluid-thermal-mechanical coupled characteristics of PCHE under different airfoil fin arrangements. The stress distribution of the single airfoil fin was studied, and a better airfoil arrangement that comprehensively considers heat transfer characteristics and stress distribution was obtained. Aiming at the high stress caused by the stress concentration at both ends of the airfoil fin, an optimized configuration combining straight channel and airfoil channel was proposed. The results show that the difference between the flow and heat transfer performance of the two optimized structures and the reference structure is only within 1.5%, but the maximum stresses of the two optimized structures are respectively reduced by 69.4% and 70.0% compared with that of the reference structure, which significantly reduces the stress intensity of PCHE. The result provides a new method to develop the airfoil PCHE with uniform stress distribution and good thermo-hydraulic performance.

关键词： printed circuit heat exchanger supercritical carbon dioxide airfoil fin thermal-mechanical coupling

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Numerical analyses of coupled thermo-mechanical behaviors of cement sheath in geothermal wells

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Underground Space 2023年第1期8卷 80-93页

作者： Hao Wang Jinlin Wang Zhichao Zhang Xiaohui Cheng State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China School of Civil Engineering Chongqing UniversityChongqing 400045China Department of Civil Engineering Tsinghua UniversityBeijing 10084China

The stability of cement sheath under high temperature and high pressure is one of the most critical issues for the durability of geother-mal well systems.In this study,a two-dimensional plane-strain finite element code was developed to investigate the coupled thermo-mechanical behaviors of the casing-cement-formation system.Different from previous linear elastic analyses,a thermoelasto-plastic con-stitutive model based on the thermodynamic theory was adopted for the cement sheath.It is shown that the finite element simulations using the proposed model provide a more accurate and realistic prediction of stress–strain responses of the cement sheath under high temperature.The results demonstrate that the radial stress concentration and the tensile strain concentration occur at both the cement–casing interface and the cement–formation interface,where the cement sheath is most likely to fail.High strength and low stiff-ness in the cement sheath and the formation are preferred for the integrity of the system.Both large thermal cycles and large differences between the internal fluid pressure and the external pressure should be avoided during operation.The new code is an alternative tool for guiding the geothermal well design.The finite element framework described herein is universal for other thermo-mechanical applications,such as energy foundations and energy tunnels.

关键词： Geothermal well thermal-mechanical coupling Finite element analysis Constitutive model Cement sheath Thermodynamic theory

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Microcrack-and microvoid-related impact damage and ignition responses for HMX-based polymer-bonded explosives at high temperature

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Defence Technology（防务技术） 2022年第9期18卷 1602-1621页

作者： Hai-jiao Xue Yan-qing Wu Kun Yang Yi Wu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing100081China

Investigating the damage and ignition behaviors of polymer-bonded explosive(PBX) under a coupled impact and high-temperature loading condition is required for the safe use of charged PBXs. An improved combined microcrack and microvoid model(CMM) was developed for better describing the thermal effects of deformation, damage, and ignition responses of PBXs. The main features of the model under typical dynamic loadings(i.e. uniaxial tension and compression, and lateral confinement) at different initial temperature were first studied. And then the effects of temperature on impact-shear sensitivity of HMX-based PBXs were investigated. The results showed that the ignition threshold velocity of shear-crack hotspots exhibits an increase from 260 to 270 to 315-325 m/s when initial temperature increases from 301 to 348 K;and then the threshold velocity decreases to 290-300 m/s with the initial temperature continually increasing to 378 K. The predicted ignition threshold velocity level of the explosives under coupled impact and high temperature loading conditions were consistent with the experimental data.

关键词： PBX thermal-mechanical coupling Numerical simulation Impact Sensitivity

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Research Progress on thermal Shock Behavior of Porous Ceramics

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China's Refractories 2022年第1期31卷 24-29页

作者： YAN Mingwei LIU Kaiqi ZHANG Jiayu SUN Guangchao LI Xiang SI Kaikai State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100019China University of Chinese Academy of Sciences Beijing 100049China

thermal-mechanical coupling effect causes a large stress within porous ceramics at high temperatures,resulting in strength attenuation and product reliability decline.thermal shock resistance is one of the key factors to characterize the reliability of ceramic materials under thermal-mechanical coupling effect.It is important to study the thermal shock resistance of the porous ceramics to evaluate their service performance and improve their service life.To better evaluate the effect of the thermal shock resistance on properties of the porous ceramics,the evaluation theories,experimental characterization methods and influencing factors about the thermal shock performance of the porous ceramics were reviewed in this paper,and some future research directions were prospected.

关键词： porous ceramics thermal-mechanical coupling thermal shock resistance evaluation theory influence factor

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A thermo-viscoelastic model for particle-reinforced composites based on micromechanical modeling

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Acta Mechanica Sinica 2021年第3期37卷 402-413,I0001页

作者： Yang Chen Xiaohao Shi Zhenqiang Zhao Zaoyang Guo Yulong Li School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710072China Institute of Biomedical Engineering and Health Sciences Changzhou UniversityChangzhou 213164China School of Science Harbin Institute of TechnologyShenzhen 518055China

Micromechanics-based constitutive models offer superior ability to estimate the effective mechanical properties for the composites,which greatly promote the computational efficiency in the multiscale analysis for composite structures.In this work,a thermo-viscoelastic model for particle-reinforced composites is proposed to estimate their thermal-mechanical coupling behaviors in terms of a micromechanics-based homogenization method in the time domain.The matrix and particles of the composites are modeled as“thermo-rheologically complex”viscoelastic materials.The temperature-dependent effective elastic strain energy ratios of particle to composite are proposed to evaluate the contributions of the matrix and particles.The thermo-viscoelastic model for the composites is then formulated by superposing the matrix and particle’s contributions.Finite element simulations based on the representative volume element models are employed to validate the constitutive model under various thermal-mechanical coupling loads.The effects of the loading rate,viscous parameter and particle content on the effective thermal-mechanical responses of the composites are also comprehensively discussed.The experimental data from literature are also employed to verify the constitutive model.The findings show that the proposed thermo-viscoelastic model can accurately predict the thermal-mechanical coupling behaviors for the particle-reinforced composites.

关键词： Particle-reinforced composites Thermo-viscoelastic model thermal-mechanical coupling Homogenization method Numerical validation

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Multi-scale thermodynamic analysis method for 2D SiC/SiC composite turbine guide vanes

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Chinese Journal of Aeronautics 2018年第1期31卷 117-125页

作者： Xin LIU Xiuli SHEN Longdong GONG Peng LI School of Energy and Power Engineering Beihang University Beijing 100083 China Navigation and Control Technology Research Institute of China Ordnance Industries Beijing 100089 China

Ceramic Matrix Composite （CMC） turbine guide vanes possess multi-scale stress and strain with inhomogeneity at the microscopic scale. Given that the macroscopic distribution cannot reflect the microscopic stress fluctuation, the macroscopic method fails to meet the requirements of stress and strain analysis of CMC turbine guide vanes. Furthermore, the complete thermodynamic properties of 2D woven SiC/SiC-CMC cannot be obtained through experimentation, Accordingly, a method to calculate the thermodynamic properties of CMC and analyze multi-scale stress and strain of the turbine guide vanes should be established. In this study, the multi-scale thermodynamic analysis is investigated. The thermodynamic properties of Chemical Vapor Infiltration （CVI） pro- cessed SiC/SiC-CMC are predicted by a Representative Volume Element （RVE） model with porosity, leading to the result that the relative error between the calculated in-plane tensile modulus and the experimental value is 4.2%. The macroscopic response of a guide vane under given conditions is predicted. The relative error between the predicted strain on the trailing edge and the experimental value is 9.7%. The calculation of the stress distribution of micro-scale RVE shows that the maximum value of microscopic stress, which is located in the interlayer matrix, is more than 1.5 times that of macroscopic stress in the same direction and the microscopic stress distribution of the interlayer matrix is related to the pore distribution of the composite.

关键词： Ceramic matrix composites Multi-scale Representative volume element thermal-mechanical coupling Turbine guide vane

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Dynamic thermo-mechanical behaviors of SME TiNi alloys subjected to shock loading

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Acta Mechanica Sinica 2020年第6期36卷 1336-1349,I0004页

作者： Lingyan Shen Yonggui Liu Mengmeng Hui School of Civil Engineering Henan Polytechnic UniversityJiaozuo454000China CAS Key Laboratory for mechanical Behavior and Design of Materials University of Science and Technology of ChinaHefei230027China

Dynamic thermo-mechanical coupling behaviors of shape memory TiNi alloy in the strain rate ranging from 300 s^−1 to 2000 s^−1 are investigated by the split Hopkinson pressure bar(SHPB)device with an infrared(IR)detection system.In stress–strain space,dynamic response shows a strong strain hardening property,however,in stress–temperature space,transformation path is particularly sensitive to the strain rate.The corresponding temperature evolution measured synchronously shows that local temperature increased associated with the forward phase transition,and it would keep the loading maximum value unchanged or decreased for unloading,depending on the strain rate.Besides,local temperature evolution was consistent with the transformation stress and its values at different points are the same.Temperature evolution and transformation deformation mechanism is then analyzed by a simple one-dimensional model.The results show that latent heat and dissipated energy are responsible for temperature variation.Furthermore,the temperature evolution with strain rate reveals that with the increase of strain rate,the phase transformation deformation mechanism undergoes a transformation from phase transition fronts propagation during lower strain rates to combination of local nucleation and front propagation during middle strain rate and to uniform nucleations during higher strain rates.The results are helpful for a passive shape memory alloy(SMA)micro-valve design.

关键词： thermal-mechanical coupling Temperature evolution Strain rate effect Phase transformation path

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GURTIN-TYPE VARIATIONAL PRINCIPLES FOR DYNAMICS OF A NON-LOCAL thermal EQUILIBRIUM SATURATED POROUS MEDIUM

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Acta Mechanica Solida Sinica 2005年第1期18卷 37-45页

作者： YangXiao InstituteofAppliedMathematicsandMechanics DepartmentofMechanicsShanghaiUniversityShanghai200444China

Based on the porous media theory and by taking into account the efects of the pore fuid viscidity, energy exchanges due to the additional thermal conduction and convection between solid and fuid phases, a mathematical model for the dynamic-thermo-hydro-mechanical coupling of a non-local thermal equilibrium fuid-saturated porous medium, in which the two constituents are assumed to be incompressible and immiscible, is established under the assumption of small de- formation of the solid phase, small velocity of the fuid phase and small temperature changes of the two constituents. The mathematical model of a local thermal equilibrium fuid-saturated porous medium can be obtained directly from the above one. Several Gurtin-type variational principles, especially Hu-Washizu type variational principles, for the initial boundary value problems of dy- namic and quasi-static responses are presented. It should be pointed out that these variational principles can be degenerated easily into the case of isothermal incompressible fuid-saturated elastic porous media, which have been discussed previously.

关键词： non-local thermal equilibrium thermal-mechanical coupling mathematical model variational principle porous media theory

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FINITE ELEMENT ANALYSIS OF THERMOELASTIC BEHAVIOR OF PIEZOELECTRIC STRUCTURES UNDER FINITE DEFORMATION

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Acta Mechanica Solida Sinica 2002年第4期15卷 312-322页

作者： Tian Xiaogeng Shen Yapeng Xian Jiaotong Univ State Key Lab Mech Struct Strength & Vibrat Xian 710049 Peoples R China

It is noted that the behavior of most piezoelectric materials is temperaturedependent and such piezo-thermo-elastic coupling phenomenon has become even more pronounced in thecase of finite deformation. On the other hand, for the purpose of precise shape and vibrationcontrol of piezoelectric smart structures, their deformation under external excitation must beideally modeled. This demands a thorough study of the coupled piezo-thermo-elastic response underfinite deformation. In this study, the governing equations of piezoelectric structures areformulated through the theory of virtual displacement principle and a finite element method isdeveloped. It should be emphasized that in the finite element method the fully coupledpiezo-thermo-elastic behavior and the geometric non-linearity are considered. The method developedis then applied to simulate the dynamic and steady response of a clamped plate to heat flux actingon one side of the plate to mimic the behavior of a battery plate of satellite irradiated under thesun. The results obtained are compared against classical solutions, whereby the thermal conductivityis assumed to be independent of deformation. It is found that the full-coupled theory predicts lesstransient response of the temperature compared to the classic analysis. In the steady state limit,the predicted temperature distribution within the plate for small heat flux is almost the same forboth analyses. However, it is noted that increasing the heat flux will increase the deviationbetween the predictions of the temperature distribution by the full coupled theory and by theclassic analysis. It is concluded from the present study that, in order to precisely predict thedeformation of smart structures, the piezo-thermo-elastic coupling, geometric non-linearity and thedeformation dependent thermal conductivity should be taken into account.

关键词： finite deformation thermal-mechanical coupling geometricalnon-linearity heat conduction

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Study on 4Cr9Si2 Martensitic heat-resistant steel in CWR

Study on 4Cr9Si2 Martensitic heat-resistant steel in CWR

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2012年先进制造技术与系统国际会议

作者： Jianghua Huang~(1,a),Jinping Liu~1,Baoyu Wang~1,Zhenghuan Hu~1 1 School of mechanical Engineering,University of Science and Technology Beijing,Beijing 10083, China

4Cr9Si2 Martensitic heat-resistant steel is inlet valve and the exhaust tappet materials. This paper is based on the constitutive relationship of 4Cr9Si2 Martensitic heat-resistant steel obtained by isothermal compression;a finite element model of Cross Wedge Rolling was build up for 4Cr9Si2 Martensitic heat-resistant steel.In the model the heat conduction between billet and the die,the convection of heat transfer,and the thermal conversion of plastic work and friction work were taken in account,the value of damage was obtained in the rolling and central porosity was analysis.Then verify the correctness of the FEM and feasibility of simulation results by the experiment.

关键词： 4Cr9Si2 Martensitic heat-resistant steel CWR FEM thermal-mechanical coupling

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