叉车前桥动力吸振器的有限元及试验分析

针对某型号叉车前桥的振动特性,设计了一种以橡胶为弹性阻尼元件的被动式动力吸振器,为便于预测吸振器力学特性,建立了以橡胶为弹性阻尼元件的该种吸振器的有限元模型,该有限元模型的分析结果与实际测试的频响曲线吻合,在该吸振器安装在某型叉车上之后,前桥处的振动幅值比未安装吸振器前的振动值明显减小.     

连续悬臂梁动力吸振器的模型研究

针对吸振器动力参数固定不可变或仅能产生离散变化的局限性问题,在连续悬臂梁的基础上通过增加滑动质量块的方式,设计了一种新型的参数可连续变化的悬臂梁吸振装置,并对其进行了共振频率、效果试验分析.为提高主体振动控制的效果又对参数进行了优化分析.结果表明,该装置对受固定频率简谐激励的主体结构进行动力吸振可行有效,动力参数连续可调.     

新型阻尼结构叶片振动特性试验研究

干摩擦阻尼结构被广泛应用于透平叶片中来降低其振动应力。文章设计并搭建了干摩擦阻尼块结构叶片振动特性测试试验台,通过测量一新型阻尼结构叶片的振动响应值,获得了不同激振力及模拟离心力转速下叶片频率响应曲线及模态阻尼比。试验结果表明：当激振力较小时（4N、5N和6N）,叶片的共振频率随模拟离心力转速的上升而不断增加,而模态阻尼比则先增加再减小,在40％模拟离心力转速工况下模态阻尼比最大,叶片减振效果最好;当激振力较大时（12N、18N和24N）,叶片振动更加剧烈,使得阻尼块接触刚度降低,叶片的共振频率接近自由叶片固有频率,而模态阻尼比随着模拟离心力转速的上升不断降低。     

基于声学黑洞结构的附加吸振器设计与开发

声学黑洞(ABH)结构能够降低弯曲波波速,实现对结构中弯曲波的控制。基于声学黑洞的这一特性,设计开发了一种基于声学黑洞结构的附加吸振器(简称吸振器),分析了其抑制振动和吸收能量的特性,探讨了不同结构参数和连接方式对其性能的影响,并验证了这种结构在板件结构振动控制领域的应用效果,此研究具有重要理论意义和工程应用价值。     

动力总成动力吸振器特性研究

采用合适的动力吸振器对汽车动力总成的弯曲共振有较好的抑制作用,动力总成工况复杂,吸振器选择不合理反而可能适得其反。通过对动力总成吸振器进行试验研究,分析了动力总成吸振器的温度特性和激励特性,并应用于动力吸振器设计,成功解决了某车型由于动力总成弯曲共振导致的车内振动噪声大的问题。     

拉索式小型风力发电机塔架结构吸振器的研发

风力发电机塔架结构的自然频率与风轮的工作频率(风叶的通过频率)相近时,将发生共振,导致风力发电机无法正常工作。文章基于动力吸振原理,建立了拉索式小型风力发电机塔架结构等效振动模型,再以6kW级拉索式小型风力发电机塔架结构的缩小模型为对象制作吸振器,用理论与试验验证吸振器的有效性。试验结果表明,吸振器能够有效减少塔架结构共振频域内的振动。     

通过测量曲轴飞轮系统扭振模态特性诊断曲轴裂纹

本文提出了扭振特性对局部结构裂纹变化敏感度的概念和数学定义,推导了模态特性、频响特性对曲轴局部结构参数的敏感度公式。通过理论分析和模态测试比较了多个振动特征量对曲轴裂纹的感应能力,推荐扭振模态阻尼(阻尼衰减因子)、频响函数模态峰、自谱模态峰为裂纹故障最佳评判量,并对曲轴模拟裂纹进行了诊断。     

高速柴油机复合式减振器的试验研究

为了详细考察复合式减振器的减振效果,设计了一种可调频的动力吸振器,在一台直列6缸车用柴油机上进行了试验。研究中开发了轴系的扭、纵、弯三维振动的测试装置,测量了动力吸振器在几个主要弯曲调谐频率下曲轴前面自由端的三维振动,并与原机进行了对比。通过对试验结果的分析,发现采用匹配合适的弯曲减振器能够有效降低曲轴的弯曲振动,抑制曲轴的纵向振动。     

测试参数误差对内燃机激振力识别精度的影响

激振力识别是内燃机振动控制的基础和重要环节,为了确定内燃机整机系统的质量、转动惯量、刚度、阻尼、质心位置等各测试参数误差对激振力(矩)的识别精度的影响,通过数值模拟生成了整机振动加速度时域信号,根据相关动力学原理编写了内燃机激振力(矩)识别程序,利用试验及经验确定了测试参数误差的波动范围,分析了多工况下的各个测试参数误差对激振力(矩)识别精度的影响。结果表明:若需二阶往复惯性力(矩)、三阶和六阶倾倒力矩识别误差小于5%,则质量测试误差需小于±4.27%,转动惯量测试误差需小于±4%,刚度测试误差需小于±20%,阻尼系数可用范围为0.075~0.125,质心偏移误差需小于±40 mm。     

动力机械动力吸振器数值优化分析

以单缸柴油机为例研究了动力吸振器动力参数的优化设计问题。传统动力吸振器动力参数设计都是在简谐激励下进行的,经理论分析动力吸振器动力参数的设计与激励频率有关,所以对于非简谐的激励确定动力参数则比较困难。以实现平台最小位移响应为目标,通过数值仿真来确定非简谐激励情况下动力吸振器的动力参数。数值仿真结果表明：数值优化方法具有很好的精度。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

生物质催化热裂解技术的研究进展

生物质催化裂解是生物质热化学转化的一种重要途径。综述了生物质催化热裂解技术使用的反应器、催化剂类型,以及催化热裂解过程中热裂解温度、吹扫气、升温速率、生物质原料等条件的影响,展望了生物质催化热裂解技术的发展趋势。