热处理淬火过程计算机模拟的现状与展望

淬火过程是温度场、组织场和应力场相互作用的复杂过程,介绍了淬火过程数值模拟的进展、内容、方法,展望了淬火过程数值模拟的发展趋势。     

基于并行计算的二次喷射式HCCI汽油机的三维数值模拟

建立了缸内直喷HCCI汽油机带进、排气道的燃烧系统的三维工作过程循环数值模型,实现了HCCI发动机包括进气、压缩、燃烧、膨胀和排气工作过程的三维循环模拟并进行了验证.首先基于并行计算进行了不同当量比(负荷)工况下HCCI发动机缸内过程的对比分析,研究了负荷对HCCI发动机着火、燃烧和排放的影响.进而模拟了缸内直喷二次喷射的HCCI发动机循环工作过程,解析了HCCI发动机着火燃烧和排放过程,揭示了HCCI发动机缸内直喷二次喷射控制着火的规律.计算结果有助于对HCCI燃烧过程的深入理解,为HCCI发动机燃烧过程的优化提供了依据.     

CO_2跨临界制冷循环理论分析

以热力学理论为基础,对CO2跨临界制冷循环的压缩过程、放热过程、膨胀过程和吸热过程分别进行了分析,为CO2跨临界制冷系统的研究提供了理论参考。     

生物质燃料层热解过程的传热传质模型研究

通过分析生物质热解过程的传热传质特点,建立了生物质燃料层热解过程的传热传质教学模型。通过数值计算,研究了生物质燃料层在热解过程中所发生的热量和质量迁移现象,分析了热解过程生物质床内部温度场的分布、生物质固体密度的变化和热解区的迁移规律。     

精馏过程节能技术

本文总结了精馏过程主要的节能技术,按照流程是否改变及是否利用过程技术对各类技术的进行分类,即过程技术节能,特殊精馏工艺和精馏塔高效材料等类型,对各个类型的主要节能方法、优缺点和适用范围进行了综述,并介绍了我国精馏过程的节能现状与趋势.     

基于热化学平衡的生物质气化过程建模

生物质气化是生物质能利用的主要形式之一。通过对生物质气化过程的分析,建立了一种基于热化学平衡机理的气化过程平衡模型。详细介绍了模型的原理、建立过程以及模型的求解和验证。计算结果表明,模型能够对生物质的气化过程中的反应特性起到预测作用,为今后生物质气化过程的参数优化和控制计算提供了一定的理论依据。     

抽水蓄能SFC拖动过程电能质量测试方案设计及应用

抽水蓄能电站SFC拖动过程易引发电能质量问题,并由此导致用电设备损坏和寿命大幅小于预期等,因此研究和制定全面系统的SFC拖动过程电能质量测试方案。结合SFC的结构和拖动过程特点等场景,描述了SFC拖动过程全站电能质量测试方案的测试范围和主要内容,并介绍了方案的应用结果,对抽水蓄能电站电能质量的系统性测量进行了有益的尝试。     

基于微可压缩流体的水力过渡过程研究

基于微可压缩流体理论建立了水力过渡过程的控制方程组,获得了水电站引水系统水力过渡过程计算的一维和二维模型,并应用于计算和模拟水电站引水系统过渡过程、调压室水位波动、流速场与压力场变化过程。结果表明,计算与试验结果基本吻合,误差小于3%,为调压室的结构设计提供了依据。     

高功率直流电弧等离子体流动传热过程的数值模拟

金刚石薄膜在现代工业和军事中具有重要应用价值,但是其制备过程中仍然存在着诸多问题,影响了其产业化发展。本文采用数值模拟的方法对影响金刚石薄膜制备的关键因素直流电弧等离子体的流动传热过程进行了研究,获得了等离子体流动与传热过程中的流场分布、温度分布、电离度分布等有关参量的分布状况,为掌握和控制电弧等离子体流动传热过程提供了理论依据和指导。     

原油管输不可逆过程火用的传递和转换规律研究

基于不可逆过程热力学的基本理论,探讨了原油管输过程各不可逆过程的强度量势场梯度驱动力作用下的火用流传递现象,结合原油管道输送过程的基本场平衡方程组和普遍化热力学体系的火用平衡动力学方程,推导了管输过程的热火用和压火用传递和转换方程,进一步建立管输过程的总火用传递方程。以某原油管道为例,对管道输送过程进行数值分析得到管输过程中热火用和压火用的传递和转换火用流分布规律,为将火用的传递转换规律应用到管道节能体系中提供理论基础和合理依据。     

Comparative analysis of the infield response of five types of photovoltaic modules

Five types of photovoltaic (PV) modules were comparatively analyzed considering the electrical output, efficiency and relative loss in efficiency, based on infield data collected in a temperate mountain climate, over 14 months. The mono-, poly-crystalline silicon, CdTe, CIS and CIGS modules were mounted on two identical platforms, installed close to a row of buildings. Based on the data collected from individual or groups of modules on the two platforms, analyses focused on the photovoltaic output, considering: the mean monthly values; the influence of the neighboring buildings; the influence of the irradiance, temperature and wind in different seasons (winter, summer); the influence of tracking on each PV module type. The qualitative analysis shows that small PV platforms installed in the built environment require accurate investigations on the air currents with influence on snow and frost retention/melting and water vapor condensation. In the temperate climate, with snowy winters and rather warm summers, the best performing modules are of poly-crystalline silicon; among thin film modules, the best output corresponds to CIGS, while the steadiest efficiency corresponds to CdTe. Tracking has a “leveling” effect on the conversion efficiency, making the PV output more predictable during days with preponderant direct solar irradiance.     

石灰炉热工参数数值分析与优化

根据炉内热平衡和物料平衡原理，建立了石灰炉内反应与传热过程数学物理模型以及石灰燃烧分解率的在线监测模型；运行计算机模拟研究了各操作参数对石灰石燃烧过程的影响，提出了改善技术经济指标的措施；采用VB进行数据通讯和实时监测编程，实现了石灰炉运行的集中监测，有利于石灰炉高效稳定运行，达到增产降耗的目标。     

Thermal network analysis of a conditioned building: The effect of location of insulation

Thermal network analysis has been applied to an air-conditioned enclosure to predict the daily variation of heat flux. The effect of putting the insulation on the concrete roof/wall has been analysed in detail. It is found that, when only the ceiling is insulated, the difference in concrete thickness, either on the top side or bottom side with a fixed thickness of insulation sandwiched in between, total concrete thickness remaining the same, does not affect the total heat flux appreciably. The contributions to the heat flux from the south and west walls are also found to be quite significant. The effect of putting the insulation on the south, as well as on the west, walls is also significant.     

The effect of adsorption of thiourea on the particle size of supported platinum nanocatalysts synthesized by chemical reduction

In this work, carbon-supported platinum nanoparticles were synthesized in the presence of varying concentrations of thiourea (TU). Because of the presence of the sulfur atom, thiourea adsorbs strongly on the forming Pt nuclei during the synthesis, affecting the rate and the extent of growth. High-intensity X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) were used to probe the effect on the crystallite size and particle size, respectively, revealing a decrease in both mean crystallite and the mean particle size for increasing concentrations of thiourea during the synthesis. An adsorption isotherm for the adsorption of thiourea on platinum nanoparticles is also discussed. Cyclic voltammetry was used to check the effect of TU on the particles as well as to obtain further knowledge on both adsorption and electrochemical oxidation behavior of thiourea on Pt surfaces. Thermal treatment effectively cleaned the electrode surface, thus providing an easy way to remove adsorbed species from the Pt surface.     

某四缸汽油机缸体螺纹滑扣失效分析

针对缸体主轴承盖螺栓螺纹在试验和装配过程中出现滑扣,对导致此现象的原因进行分析。主要从缸体螺纹设计、加工、缸体铸造质量、螺栓设计、螺栓加工等方面进行详细分析,结果表明,主要原因为缸体螺纹加工工艺选择不合适、螺栓旋合长度偏小、螺栓结构设计不合理和初始力矩选择不合适。     

模态分析在排气歧管支架开发中的应用

主要研究典型的排气歧管催化器支架的开发。发动机耐久性试验失效,靠近发动机排气端的失效主要与支架失效有关。通过应用NVH理论知识,以及材料的疲劳理论,采用CAE及试验的方式,主要是排气歧管催化器模态分析,将排气歧管的结构模态频率提高到避开发动机的共振频率。介绍了支架的模态分析过程以及谐振试验,进行了耐久性验证,并归纳总结成完整方法作为设计参考。     

The effect of fouling on nucleate pool boiling of small wires

Pool boiling experiments with small diameter wires were conducted in earth gravity and microgravity conditions. Bare wire and fouled wire with a scale deposition of calcium carbonate was used. The wettability on the scale wire was higher than that on the bare wire. Though more vigorous bubbling was observed on the scale wire when compared to that on the bare wire at the same heat flux, the boiling curve for the scale wire was approximately the same as that on the bare wire. However, the critical heat flux (CHF) on the scale wire was higher than that of the bare wire. On the scale wire, the departure diameter of bubbles was relatively smaller than that on the bare wire. The smaller diameter of bubbles detaching from the scale wire is considered to be due to the high wettability and high nucleation site density. As the result, the coalescence of bubbles near the wire was prevented, and the CHF was delayed and increased on the scale wire when compared to that on the bare wire. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(5): 316–329, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20016     

Effect of Environmental Temperature on the Fatigue Crack Propagation Behavior of Cemented Carbides

Cemented carbides have been utilized as high speed turning tools or heat-resistant tools. So, it is necessary to study fatigue crack propagation behavior of the cemented carbides under high temperature environment in order to understand, or to grasp their capabilities under such a severe environmental conditions. Many studies on static fatigue, on creep and on monotonic mechanical properties of the cemented carbides have been conducted under high temperature environment. However, studies on cyclic fatigue of the cemented carbides under the above environment are very few and limited. In the present study, cyclic fatigue tests were conducted on cemented carbides under high temperature environment. The tests were performed at two stress ratios, R = 0.1 and 0.5. In addition to these cyclic fatigue tests, static fatigue tests at R = 1 were also conducted to study more detail about the effects of cyclic stress, stress ratio and temperature on the fatigue crack propagation behavior of the cemented carbides.     

STAAD/Pro在锅炉钢结构设计中的应用

根据STAAD/Pro的特点,结合锅炉钢结构设计的需要,简要介绍STAAD/Pro在锅炉钢结构设计中模型建立、参数设置、结构分析等具体问题的解决办法。     

串列叶栅前后排叶片周向相对位置对离心压气机性能的影响

串列叶栅前后排叶片相对位置对串列扩压器的性能有重要影响.根据离心叶轮出口气流参数设计了一离心式串列叶栅扩压器,并利用数值模拟方法在前、后排叶栅周向相对位置分别为10%、20%、30%、40%、50%、60%、70%、80%和90%时对离心压气机级进行了计算和分析,研究周向相对位置变化对离心压气机性能的影响以及作用机理.数值模拟结果表明:随着前后排叶栅周向相对位置变化,后排叶栅前缘滞止高压区相对前排叶栅的位置发生了变化,影响了前排叶栅压力面的压力分布,从而改变了前排叶栅压力分布及大小;当前后排叶栅周向相对位置为30%时,扩压器性能达到最佳,使压气机总压比和等熵效率最大,稳定工作范围增大;前后排叶栅所形成的渐缩通道可抑制后排叶栅吸力面边界层的分离.