冷却性能良好的风冷活塞式压缩机

导言压缩空气必须以经济方式获得,因在各个工业部门它是一种不可缺少的能源。欲使压缩空气价格合适,其首要前提是压缩机的投资费用应低,同时生产成本也应尽可能低廉。风冷活塞式压缩机能理想地符合上述二点要求。先进的压缩机制造厂一直最喜采用风冷式。现代风冷式压缩机组及工业用压缩机的研制系依据空气动力学理论,俾使冷却系统得到特别良好的效果。     

2Д100柴油机活塞的镀锡

根据现行技术条件的规定,当活塞裙部的镀锡层磨耗超过150厘米~2时活塞即报废。在更换缸套或活塞时,当活塞裙部的镀锡层磨耗超过30厘米~2时活塞就予以报废。     

高参数船用蒸汽透平设计的一些问题

本文是从各种文献中收集得的一些有关资料,这些资料叙述了在汽轮机制造业中运用高参数蒸汽所取得的经验,高参数蒸汽对船用蒸汽轮机主要特性的影响及改善这些特性的各种措施。     

高速柴油机的制造

本文简要地介绍了 Davey Paxman公司的柴油机制造工艺及程序。对于一种系列的柴油机,其部件制造的互换主要原则是:采用有专用机床的流水作业线或可以生产相同的主要     

最佳性能点燃式发动机的燃烧室设计(续)

<正> 4.连续循环中的不稳定性 众所周知,每次燃烧情况的不稳定使各循环之间、各缸之间所产生的压力不同。然而,若点火时刻为循环中的最佳点,则它的燃烧率接近于平均值;提前点火使燃烧循环加快,而滞后点火使燃烧循环减慢。而任何偏离循环的正常水平则意味着效率上的损失、功率上的损失,汽车驱动性降低。同时由于非均衡循环而导致非最佳点火时刻,引起废气失控。同样,最快燃烧速度的循环确定辛烷值极限值,因此其压缩比必须低于在循环中能连续反复进行燃烧的压缩比。     

摩擦阻力

11.粘性液体中物体运动概况把作用于船体浸水表面切线方向各单位力之合力,分成沿船体运动方向之分力,此分力称为摩擦阻力。在液体表面最近处之液体粘性最大。故研究固体近旁之液体流动为研究摩擦力之基础。一些研究的结果表明,液体速度在行动的固体     

論未来貨車的载重量

为了提高铁路运輸能力,除了采用新型牵引动力以外,还必須补充一批新型高效率的大吨位車辆。这些車辆应具有自重系数小,高速运行时运用可靠,有可能实行机械化装卸,及其造价最低等特点。尽可能地增大貨車的載重量及其单位长度的載荷,已具有特别重大的意义。这两个指标决定了机車車辆     

发动机活塞用不含镍的铝合金

<正> 汽车发动机活塞铸造用铝合金在工作温度范围内必须有较高的静力强度、动力强度和疲劳强度,同时温度膨胀系数低,耐磨性高,耐热性强。铝硅合金能在最大程度上满足上述要求。目前在苏联最普遍获得推广使用的有:КС245、АЛ30和АК10M2H牌号的合金(含硅13％以下),这些合金适用于制造柴油机的活塞,而AЛ25合金则可应用于制造拖拉机上柴油机的活塞。     

考虑不确定性因素的路径优化(英文)

A route optimization methodology in the frame of an onboard decision support/guidance system for the ship’s master has been developed and is presented in this paper.The method aims at the minimization of the fuel voyage cost and the risks related to the ship’s seakeeping performance expected to be within acceptable limits of voyage duration.Parts of this methodology were implemented by interfacing alternative probability assessment methods,such as Monte Carlo,first order reliability method(FORM) and second order reliability method(SORM),and a 3-D seakeeping code,including a software tool for the calculation of the added resistance in waves of NTUA-SDL.The entire system was integrated within the probabilistic analysis software PROBAN.Two of the main modules for the calculation of added resistance and the probabilistic assessment for the considered seakeeping hazards with respect to exceedance levels of predefined threshold values are herein elaborated and validation studies proved their efficiency in view of their implementation into an on-board optimization system.     

双平面焊接圆管截面DKT节点的中心撑杆鞍点及冠点位置的应力集中系数(英文)

A set of parametric stress analyses was carried out for two-planar tubular DKT-joints under different axial loading conditions.The analysis results were used to present general remarks on the effects of the geometrical parameters on stress concentration factors(SCFs) at the inner saddle,outer saddle,and crown positions on the central brace.Based on results of finite element(FE) analysis and through nonlinear regression analysis,a new set of SCF parametric equations was established for fatigue design purposes.An assessment study of equations was conducted against the experimental data and original SCF database.The satisfaction of acceptance criteria proposed by the UK Department of Energy(UK DoE) was also checked.Results of parametric study showed that highly remarkable differences exist between the SCF values in a multi-planar DKT-joint and the corresponding SCFs in an equivalent uni-planar KT-joint having the same geometrical properties.It can be clearly concluded from this observation that using the equations proposed for uni-planar KT-connections to compute the SCFs in multi-planar DKT-joints will lead to either considerably under-predicting or over-predicting results.Hence,it is necessary to develop SCF formulae specially designed for multi-planar DKT-joints.Good results of equation assessment according to UK DoE acceptance criteria,high values of correlation coefficients,and the satisfactory agreement between the predictions of the proposed equations and the experimental data guarantee the accuracy of the equations.Therefore,the developed equations can be reliably used for fatigue design of offshore structures.