基于热-结构耦合模型的高速电主轴温升特性分析与实验研究（英文）

为解决热变形对主轴寿命及加工精度的影响,对高速电主轴的温升特性进行研究。首先建立了电主轴的热结构耦合模型,然后利用ANSYS软件进行热态模拟,分析稳态温度场的分布以及电主轴的热变形情况,最后探讨了主轴转速与切削力的变化对电主轴温度的影响。研究结果表明:所用方法可有效模拟电主轴工作过程中温度场分布以及热变形,仿真与实验结果基本一致,为电主轴温度控制提供参考。

水下航行器艉轴球面机械密封热-结构耦合分析

针对船舶轴系校中不良、轴承磨损等因素会导致艉轴平面机械密封面出现垂向偏移,严重影响密封面的接触压力、温度和变形等密封性能的问题,应用有限元方法建立水下航行器艉轴球面机械密封热-结构耦合模型,在不同的潜深和轴转速条件下,分析轴线垂向偏移对球面机械密封的接触压力、温度和变形状况的影响规律,结果表明,在轴线有垂向偏移的情况下,密封球面的接触压力、温度和变形与无偏移相比变化很小,说明球面机械密封具有良好的自位能力,能在不同工况条件下保持较稳定的密封性能。

内蒙古赤峰市热水镇地热田地球物理调查

热水镇热构造背景具有略厚的地壳,稍低的大地热流和壳内相对的低温的特征.本区不具备浅部形成高温热源的火山地质背景.从西、北部山区渗透的天水,在深部被晚期侵入的花岗岩和玄武岩以热传导的形式加热,再沿发育的的断裂、裂隙上升到浅部形成地热田浅层热水储集层.地热田具有向北西—南东和南西—东北东方向伸展的趋势.

张家口市地热资源赋存特征及形成机理研究

【研究目的】张家口市地热温泉资源丰富,目前地热资源勘查及研究工作主要集中于地热温泉出露地区,其余地区基本空白。本文通过分析研究深部地热赋存特征、水化学特征、形成机理及热储结构关系,研究总结不同地热资源类型及热储结构中地热资源富水性特征,指导山区空白区地热资源勘查开发利用及研究,助力“双碳”目标实现。【研究方法】以河北地矿局开展的张家口市地热温泉资源详细调查项目为基础,在充分分析张家口市地热资源的分布、热储埋藏条件和赋存特征基础上进行成因机理和地热水形成环境研究,并通过实例分析每种地热类型的赋存特征与优势。【研究结果】以典型区为代表,经大量数据分析研究发现:不同地热资源类型及热储结构中地热温泉(井)的水量、水温、水化学组分存在一定差异。【结论】将张家口地热资源分三种地热资源类型、七种热储结构模型,为河北省山区地热资源勘查开发提供科学理论支撑。

东海地区地热场综述

综述了东海地区地热场的特征及研究进展,根据收集的各航次热流值资料,绘制了东海地区的热流值分布图,并根据热流值的分布特点将东海地区分为陆架区、冲绳海槽区、琉球岛弧和海沟区、菲律宾海盆区等4个区块,详细分析了它们的热流分布成因,在已有的东海南北热结构模型基础上对东海南北热结构差异进行了分析。南冲绳海槽区的地壳热流值和地壳减薄程度都明显高于北冲绳海槽及其它各区,说明高热流值起源于地幔抬升和地壳的减薄,东海的扩张已经从冲绳海槽北部转移到南部。

斜梁型电热微致动器的输出位移计算及实验

为了计算斜梁型电热微致动器的输出位移,基于电-热分析和热平衡原理建立了电热微致动器的电热耦合稳态传热方程。对热-结构进行了分析,运用力法原理建立了微致动器的位移计算模型。然后,用有限元法和实际测试对比验证了温度分布和输出位移的理论值,得到了一致性很好的结果。最后,分析了微致动器输出位移的保持性和重复性,以及结构参数和工艺对微致动器输出位移的影响。分析表明:斜梁的长宽比和倾角是影响微致动器输出位移的主要参数,工艺对输出位移有影响。实验结果表明:9V和18V电压下,微致动器的最大位移分别为0.85μm和2.3μm,与理论计算结果相对误差为2.2%和12.8%,实测值与理论值误差较小,表明本文推导的斜梁型电热微致动器的输出位移计算公式合理,能够为该类微致动器的设计和计算提供理论依据。

水火弯板梯形加热变形机理研究

水火弯板热成形方法通过对钢板的加热和冷却来实现板的变形,达到符合要求的曲面形状,是目前国内外主流船体外板加工方式。梯形加热是一种新型的加工方式,本质上属于收边加热,是收边加热工艺当中板边加热面积最大的一种成形方式,成形效果好。基于Ansys有限元仿真软件,在单加热线和"双重"加热线研究的基础上,对梯形加热的温度场和变形场进行研究,得出一系列温度场和变形场的计算结果,为预测梯形加热工艺的变形和将来实现水火弯板自动化加工奠定一定的研究基础。

海口双子塔-南塔钢结构抗火设计

海口双子塔-南塔结构体系外侧为巨型钢管混凝土柱+钢支撑框架,内部为钢板混凝土核心筒,二者之间为钢结构组合楼盖,需进行抗火设计。采用临界温度法对结构进行抗火设计,基于抗火设计结果建立热-固耦合整体结构模型,继而进行抗火灾连续倒塌分析。分析时考虑了高温下构件材料的刚度、屈服强度等折减以及构件的温度应力,同时对耐火极限后的构件损坏进行了评价。结果表明,采用临界温度法抗火设计以及基于整体结构的火灾全过程分析,基本可实现建筑结构在火灾时的抗连续倒塌设计目标,其中大跨组合钢次梁为防连续倒塌薄弱构件,转换梁及钢结构节点需进行防火加强。

Local structure of calcium silicate melts from classical molecular dynamics simulation and a newly constructed thermodynamic model

The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.

基于壳温的IGBT模块键合引线疲劳寿命预测

为了研究功率循环下键合引线的疲劳寿命,提高IGBT模块的可靠性,文中提出了一种基于壳温的键合引线寿命预测方法。首先对IGBT模块进行功率循环测试,探究了键合引线的疲劳失效机理;然后建立IGBT模块的电—热—结构强耦合模型,分析了模块在功率循环载荷下的电、热、结构特性。依据键合引线的应变情况和实验测得的疲劳曲线,评估键合引线的疲劳寿命,并在壳温基础上建立了其寿命预测模型,对比测试结果验证了该模型的准确性;最后提出了铜键合引线的改进方案。根据易测量的壳温来确定键合引线的使用寿命,提前更换器件,能降低IGBT模块的故障率。

三塔自锚式悬索桥主缆抗火性能评估方法

提出了一种简易的桥梁结构抗火性能评估方法。首先,通过开展构件传热分析,获取了车致火灾下构件温度场时程曲线;建立了全桥热-结构耦合作用模型,对全桥结构高温下静力响应及安全性进行了分析与评估。然后,以某钢-混简支梁试件为对象,数值模拟分析了火灾下构件温度场及静力响应,并将分析结果与试验结果进行对比以验证所建模型的准确性。最后,以某悬索桥为工程背景,开展了油罐车、货车、客车及小汽车等4种车型发生火灾工况下构件传热分析及结构响应分析;根据自定义缆索损伤评估标准,采用所提出的评估方法对主缆局部损伤状况进行了评估。研究表明:油罐车发生火灾对结构的危害最严重,主缆最高温度可达830℃,虽然跨中挠度仅增加160 mm,但主缆产生了严重的不可逆损伤;所提出的评估方法可用于大跨径缆索承重桥梁结构抗火性能及安全性分析。

基于UG与ANSYS Workbench的齿轮箱体热-结构耦合分析研究

结合虚拟样机技术、有限元分析技术和热应力学理论,使用UG NX8.0建立齿轮箱体的虚拟样机模型。通过UG与ANSYS Workbench14.5的无缝链接,建立了齿轮箱体三维有限元模型;基于有限元理论对有限元模型进行热-结构耦合分析,得到齿轮箱体的温度场分布和热变形,确定了热应力和变形的集中部位,给出了影响温度场分布和热变形的因素。通过对有限元仿真结果分析表明,该热-结构耦合分析所建模型,可为复杂重载传动的发热量大工况下的齿轮箱体的结构设计、集成设计及热量均一优化设计提供可靠分析依据。

H型钢混组合梁耐火极限时间研究

为探究H型钢混组合梁的耐火极限时间,采用ANSYS软件建立H型钢混组合梁的热-结构耦合计算模型,分析了火源类型、外荷载大小、腹板厚度、受火区长度对H型钢混组合梁耐火极限时间的影响。结果表明:在设定的火灾场景下,油罐车燃烧时H型钢混组合梁的耐火极限时间为36 min,而小汽车的燃烧不会造成H型钢混组合梁的下挠破坏;外荷载越大、腹板越薄、受火区越长,H型钢混组合梁的耐火极限时间越短,其耐火极限时间最多分别缩短了11、8、8 min。在此基础上提出了提升H型钢混组合梁耐火极限时间的建议。

Analytical Model for Predicting the Heat Loss Effect on the Pyrolysis of Biomass Particles

This paper presents the combined influence of heat-loss and radiation on the pyrolysis of biomass particles by considering the structure of one-dimensional, laminar and steady state flame propagation in uniformly premixed wood particles. The assumed flame structure consists of a broad preheat-vaporization zone where the rate of gas-phase chemical reaction is small, a thin reaction zone composed of three regions: gas, tar and char combustion where convection and the vaporization rate of the fuel particles are small, and a broad convection zone. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number is large and the equivalence ratio is larger than unity(i.e.u≥1). The principal attention is made on the determination of a non-linear burning velocity correlation. Consequently, the impacts of radiation, heat loss and particle size as the determining factors on the flame temperature and burning velocity of biomass particles are declared in this research.

Analysis of 13Cr bloom solidification structure using CA-FE model

Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.

Structural Basis for the Thermostability of Sulfur Oxygenase Reductases

The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.

Numerical simulation on conjugate heat transfer of turbine cascade

Numerical simulation on conjugate heat transfer of an internal cooled turbine vane was carried out. Numerical techniques employed included the third-order accuracy TVD scheme, multi-block structured grids and the technique of arbitrary curved mesh. Comparison between results of commercial CFD codes with several turbulence models and those of this code shows that it is incorrect of commercial CFD codes to predict the thermal boundary layer with traditional turbulence models, and that turbulence models considering transition lead to more accurate heat transfer in thermal boundary layer with some reliability and deficiency yet. The results of this code are close to those of CFX with transition model.

Geodynamic modeling of thermal structure of subduction zones

During subduction processes, slabs continuously have heat exchange with the ambient mantle, including both conduction and advection effects. The evolution of slab thermal structure is one of the dominant factors in controlling physical and chemical property changes in subduction zones. It also affects our understanding of many key geological processes, such as mineral dehydration, rock partial melting, arc volcanism, and seismic activities in subduction zones. There are mainly two ways for studying thermal structure of subduction zones with geodynamic models: analytical model and numerical model. Analytical model provides insights into the most dominant controlling physical parameters on the thermal structure, such as slab age, velocity and dip angle, shear stress and thermal conductivity, etc. Numerical model can further deal with more complicated environments, such as viscosity change in the mantle wedge, coupling process between slabs and the ambient mantle, and incorporation of petrology and mineralogy. When applying geodynamic modeling results to specific subduction zones on the Earth, there are many factors which may complicate the process, therefore it is difficult to precisely constrain the thermal structure of subduction zones. With the development of new quantitative methods in geophysics and geochemistry, we may obtain more observational constraints for thermal structure of subduction zones, thus providing more reasonable explanations for geological processes related to subduction zones.

Features of rainfall and latent heating structure simulated by two convective parameterization schemes

Using the latest version of SAMIL (Spectral Atmosphere Model of IAP LASG) developed by LASG/IAP,we evaluate the model performance by analyzing rainfall,latent heating structure and other basic fields with two different convective parameterization schemes:Manabe Scheme and Tiedtke Scheme.Results show that convective precipitation is excessively overestimated while stratiform precipitation is underestimated by Tiedtke scheme,thus causing less stratiform rainfall proportion compared with TRMM observation.In contrast,for Manabe scheme stratiform rainfall belt is well simulated,although precipitation center near Bay of Bengal (BOB) spreads eastward and northward associated with unrealistic strong rainfall downstream of the Tibet Plateau.The simulated latent heating structure indicates that Tiedtke scheme has an advantage over Manabe scheme,as the maximum convective latent heating near middle of troposphere is well reproduced.Moreover,the stratiform latent heating structure is also well simulated by Tiedtke scheme with warming above freezing level and cooling beneath freezing level.As for Manabe scheme,the simulated maximum convective latent heating lies near 700 hPa,lower than the observation.Additionally,the warming due to stratiform latent heating extends to the whole vertical levels,which is unreasonable compared with observation.Taylor diagram further indicates that Tiedtke scheme is superior to Manabe scheme as higher correlation between model output and observation data is achieved when Tiedtke scheme is employed,especially for the temperature near 200 hPa.Finally,a possible explanation is addressed for the unrealistic stratiform rainfall by Tiedtke scheme,which is due to the neglect of detrained cloud water and cloud ice during convective process.The speculation is verified through an established sensitivity experiment.

Prediction of Thermal Behavior of Pyrolyzed Wet Biomass by Means of Model with Inner Wood Structure

A simplified one-dimensional transient model for biomass pyrolysis in a fixed bed cylindrical reactor has been formulated and experiments have been carded out to verify the calculation results regarding temperature distribu- tion. The mathematical model accounts for mass, momentum and heat transfer, including moisture evaporation and convection of pyrolysis gases. Numerical simulation has allowed to predict temperature and heat flux distri- bution, and the dynamics of feedstock devolatilization. Special attention has been devoted to the analysis of the effect of biomass moisture content on the pyrolysis process. The model of moisture vaporization in biomass bed was proposed, which included structure of surface of biomass particles. Assuming that vaporization occurs on the border of the dry and wet areas of the bed, the flux of water vaporization depends on the specific surface area of the particles and overall heat flux.