某型增压器主轴断裂原因分析

针对一起增压器主轴变截面处断裂故障,对主轴断口进行了宏观与微观分析.结果 表明:主轴变截面处过渡圆角加工过小且形成尖锐交面,是导致主轴发生疲劳断裂的根本原因.通过改进主轴加工工艺,上述问题得到解决.     

直喷式柴油机火焰浮起不对称性的数值模拟

为了合理评价直喷式柴油机湍流扩散燃烧火焰浮起的不对称性,建立了一个新的评价体系.该评价体系包括一个评价平面系、度量标准以及若干特征参数的定义,并在该评价体系内以数值模拟的方式研究了直喷式柴油机湍流扩散燃烧火焰浮起不对称性的相关问题.在所建CFD三维数值分析模型的有效性得到相关试验数据的验证后,采用验证后的模型分别研究了火焰浮起不对称性的各表征参数随时间发展、贴壁程度和涡流转速的变化趋势.分析结果表明,喷油油束的贴壁程度以及缸内的涡流转速是产生火焰浮起不对称性的主要原因.该研究为采取有效措施调控火焰浮起长度、降低柴油机碳烟排放奠定了基础.     

共轨系统高压泵用进油流量控制阀的开发

应用有限元分析软件建立了进油流量控制阀的仿真计算模型,自主开发了共轨泵用进油流量控制阀。确定了基本结构参数并进行优化,缩短了开发周期。设计开发了试验系统验证了进油流量控制阀的性能。试验结果表明:自主开发的进油流量控制阀电流-流量曲线线性度好,电流上升和电流下降的电流-流量曲线误差小,进油流量控制阀的轨压调节响应特性在0.2s以内,完全能满足共轨系统的工作要求。     

多油楔动压轴承的修理

活动多油楔动压轴承具有主轴刚度好 ,回转精度高 ,磨损小等优点 ,因此被广泛应用于磨床主轴的支承。活动多油楔动压轴承 ,常见的有短三瓦和长五瓦两种类型 ,支承点分可调和固定两种形式。其特点区别在于 :前者承载能力稍差 ,但制造容易 ,装配较简单 ,维修方便。后者回转精度高 ,承载能力大 ,使用寿命长 ,但装配及维修时技术性较高。对于活动多油楔动压轴承的修理 ,除了要掌握必要的修理知识和一定的操作技能外 ,经验对于修理来讲也是非常重要和不可缺的。现本人根据多年的磨床维修实践 ,总结出活动多油楔动压轴承修理过程中应注意的几点 ,仅…     

注油泵出口压力对抽水蓄能机组推力轴承油膜特性的影响研究

为探究洪屏电站机组在抽水调相启动过程中高压注油泵出口压力降低对轴承油膜表面压力分布和承载力的影响,本文建立了1/12推力轴瓦模型.采用结构化网格和非结构化网格相结合的方式对计算域进行空间离散,基于ANSYS Fluent软件,结合N-S方程、SST k-ω湍流模型,对机组启动过程中注油泵出口压力最低点对应的转速工况进行数模计算.结论如下:进油压力变化对油膜表面压力分布规律的影响并不大,高压力区总是位于瓦面中心靠近主轴位置,呈椭圆形分布,以压力递减的趋势向外一圈一圈扩散;进油压力主要影响油膜表面的压力值大小,且随着进油压力不断增加,油膜表面最高压力几乎呈线性增加.针对注油泵因启动压力降低而频繁报警的问题,经计算,建议将注油泵低压报警值从原来的6.7MPa调整到5.5MPa.     

内燃机曲轴滑动轴承(轴瓦)设计计算(Ⅱ)

5轴瓦结构要素形状、尺寸、公差5.1油槽5.1.1油槽形状、尺寸、公差主轴瓦的油槽是为向连杆轴承供油而设置的,其宽度和深度尺寸取决于供油量,并与轴颈油孔尺寸有关。两种油槽形状、尺寸与极限公差应符合GB/T3162-91规定,参照表30和表31。     

4JR3柴油机轴向间隙检测数值过小的工艺解决方案

对4JR3柴油机曲轴轴向间隙检测数值过小进行分析,详细分析各零部件对轴向间隙的影响,在装配中消除主轴止推瓦错位对曲轴轴向间隙的影响。     

9F燃气轮机透平轴承漏油分析及处理

某燃气轮机电厂9F燃气轮机存在透平轴承漏油现象,影响机组安全稳定运行。通过分析排查,确定透平轴承漏油的原因为油封齿间隙变大、进油压力过大,或者油封回油能力不够,并采取一系列改造措施,如更换节流孔板以降低进油压力、油封齿槽开孔以增加回油量,以及减少油封齿间隙,最终透平轴承漏油问题得到解决。研究成果可为9F燃气轮机解决类似的问题提供一定的借鉴意义。     

进油横腔对共轨喷油器喷油性能的影响研究

在喷油性能试验中,喷油器总成上的进油横腔分为无进油滤芯和有进油滤芯2种.为了分析不同进油横腔对喷油器性能的影响,选取无进油滤芯和有进油滤芯的横腔安装在同一喷油器总成上,进行不同轨压下的喷油性能测试.测试结果结合计算流体动力学(CFD)进行流动仿真分析,发现进油横腔对共轨喷油器喷油量及其均方差有一定的影响,对喷油持续期影...     

柴油两段喷射中预喷对主喷燃烧特性影响试验研究

采用可视化定容弹搭配高速数码相机研究柴油两段喷射过程中预喷对主喷喷雾在低温下的燃烧特性的影响。通过对单段喷雾燃烧过程的试验研究发现,随喷射压力增大单段喷雾燃烧的着火延迟期与燃烧持续期减小,而火焰浮起长度与液相长度增大。同时,在相同喷射压力与喷射脉宽下对比单段喷雾燃烧过程与两段喷射主喷燃烧过程得到:两段喷雾的主喷着火位置更靠近喷嘴;主喷的着火延迟期大大缩短,但预喷量对其影响较小;两段喷雾的主喷燃烧持续期增大,且随着预喷量的增大而增大;两段喷雾的主喷燃烧火焰浮起长度小于单段喷雾燃烧火焰浮起长度,且随着预喷量的增大略有增大;两段喷雾燃烧的液相长度小于单段喷雾燃烧的液相长度,且随着预喷量的增大而减小。     

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。