共查询到20条相似文献,搜索用时 93 毫秒
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针对传统架空输变电线路杆塔结构可靠性分析方法没有明确杆塔可靠度,导致存在可靠性分析效果较差的问题,提出基于蒙特卡罗法的架空输变电线路杆塔结构可靠性分析方法。依据架空输变电线路,分析架空输变电线路杆塔结构。采用蒙特卡罗法,获取架空输变电线路杆塔可靠度,随机抽样分析架空输变电线路杆塔结构的可靠性,确定结构是否出现失效情况,利用随机变量统计法,并结合正态分布函数,得到杆塔结构可靠性与实际失效概率的关系,实现对架空输变电线路杆塔结构可靠性的分析。实验结果表明,该方法可靠性分析性能更好,有助于保证整个电力网络的安全有效运行。 相似文献
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基于ANSYS的锻件感应加热温度场的数值模拟研究 总被引:2,自引:0,他引:2
针对感应加热过程中工件温度难以测量的问题,应用电磁学和传热学基本理论,建立了锻铸坯料电磁场和温度场分布的数学模型,运用ANSYS软件对感应加热过程温度分布进行变参数研究,为揭示铸坯感应加热过程的规律、优化工艺参数提供理论依据。 相似文献
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以相变材料石蜡作为研究对象,采用数值模拟方法分析同心套管蓄热装置(以下简称蓄热装置)内换热管与石蜡相变的温差(以下简称换热温差)对石蜡相变传热的影响。研究石蜡在不同换热温差下随时间变化的液相率和熔化速率。6种工况下的相变传热过程均为自然对流传热与导热的共同作用,自然对流传热对熔化过程起关键作用,加快了石蜡的熔化速率,上半部分的熔化速率远大于下半部分,造成石蜡液相率分布的不均匀性。换热温差越大,相同时刻的石蜡液相率越大。下半部分未熔化的石蜡未受到浮升力的作用,且未熔化的石蜡离加热管壁面越来越远,导致热阻越来越大,熔化需要的时间越长。采用3/4熔化时间能够提高蓄热效率。 相似文献
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对椭圆芯管矩形翅片和大功率晶闸管用热管散热器偏心圆芯管矩形翅片的传热进行了分析和数值模拟,获得了相应的肋效率曲线,并与已有的近似解作了比较。初步考查了偏心度、材料变物性和翅基温度的不均匀性对偏心圆芯管矩形翅片传热的影响。 相似文献
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Study on the thermal ignition of gasoline-air mixture in underground oil depots based on experiment and numerical simulation 总被引:1,自引:0,他引:1
The study on the special phenomenon, occurrence process and control mechanism of gasoline-air mixture thermal ignition in underground oil depots is of important academic and applied value for enriching scientific theories of explosion safety, developing protective technology against fire and decreasing the number of fire accidents. In this paper, the research on thermal ignition process of gasoline-air mixture in model underground oil depots tun- nel has been carried out by using experiment and numerical simulation methods. The calculation result has been demonstrated by the experiment data. The five stages of thermal ignition course, which are slow oxidation stage, rapid oxidation stage, fire stage, flameout stage and quench stage, have been firstly defined and accurately descried. According to the magnitude order of concentration, the species have been divided into six categories, which lay the foundation for explosion-proof design based on the role of different species. The influence of space scale on thermal ignition in small-scale space has been found, and the mechanism for not easy to fire is that the wall reflection causes the reflux of fluids and changes the distribution of heat and mass, so that the progress of chemical reactions in the whole space are also changed. The novel mathematical model on the basis of unification chemical kinetics and thermodynamics established in this paper provides supplementary means for the analysis of process and mechanism of thermal ignition. 相似文献
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Multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation 总被引:1,自引:0,他引:1
A free-piston linear alternator (FPLA) is being developed by the Beijing Institute of Technology to improve the thermal efficiency relative to conventional crank-driven engines. A two-stroke scavenging process recharges the engine and is crucial to realizing the continuous operation of a free-piston engine. In order to study the FPLA scavenging process, the scavenging system was configured using computational fluid dynamics. As the piston dynamics of the FPLA are different to conventional crank-driven two-stroke engines, a time-based numerical simulation program was built using Matlab to define the piston’s motion profiles. A wide range of design and operating options were investigated including effective stroke length, valve overlapping distance, operating frequency and charging pressure to find out their effects on the scavenging performance. The results indicate that a combination of high effective stroke length to bore ratio and long valve overlapping distance with a low supercharging pressure has the potential to achieve high scavenging and trapping efficiencies with low short-circuiting losses. 相似文献
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The specific characteristics of the Greek geothermal fields on the volcanic islands of Milos and Nisyros are described, with emphasis on the characteristics affecting well casing. Overpressure, high temperatures and highly saline brines are typical features of the Greek fields. A new treatment of the different load conditions along the casing string in proposed that takes into consideration the possible formation overpressure, the axial thermal stresses and their effect on burst and collapse resistance. This treatment is further applied to some typical wells that have experienced casing failure. 相似文献
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针对U型地埋管换热器的特点,在分析单井换热器换热量的基础上,考虑到多井换热器井与井之间传热的相互干扰,提出了一种用于U型地埋管井群换热器数值计算的9井模型,这种模型在数值计算时既能代表一般井群换热的规律,又便于计算机处理,为实际工程中分析井群换热规律提供了很好的理论依据。 相似文献
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建立了蒸汽喷射器热力学模型,并验证了该模型性能及结构计算的可靠性。并针对实际情况中,对该模型进行了动态模拟。结果显示:当工作流体的温度升高时,工质流体的质量流量都会增加,引射系数存在峰值,峰值所对应温度为热力学模型设定温度值;当引射流体的温度升高时,其质量流量也会随之增大,而工作流体的质量流量则较稳定,因此引射流体温度与压力的升高可以改善喷射器的性能;当背压升高时,在一定压力范围内,工质流体的质量流量都趋于稳定,而当背压超过热力学模型设定背压值时,引射流体的质量流量便随背压的升高而急剧下降,喷射器性能严重恶化,故认为该压力值为喷射器的临界背压。本文研究结果对喷射器的设计计算具有一定的指导作用。
关键词:蒸汽喷射器;热力学模型;数值模拟;引射系数 相似文献
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液流框是锌溴液流电池电堆的核心部件之一,为了对已付诸应用的液流框流道设计进行评估,本文针对流道建立物理模型,以真实电解液物性参数为研究对象,借助数值模拟,进行流体仿真计算(CFD).文章详细探讨了电解液在流道内的流场分布,出口流量均匀度,流道进出口压差以及不同黏度与进口流量对压降的影响.结果表明:现有的流道设计可实现各出口流量均等,但电解液在扇形坡面设计并未能实现均匀分布,坡面结构有待优化;250 mL/min,0.018 Pa·s工况下的电解液在流道内的压降为22.3 kPa;电解液在流道内的压差与黏度的0.7次方成正比,与流量的1.3次方成正比. 相似文献
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电助熔炉采用电极直接对物料加热,广泛应用于玻璃生产、冶金、固废处理领域,炉内电阻设计是电极助熔炉设计的关键指标。采用数值模拟方法,在二维电阻计算公式的基础上,分析浆液深度与宽度约束对电阻的影响,计算三维三相三电极底插熔融炉的电阻,修正了现有的电阻计算公式。针对熔融炉实验平台,对比实验结果、数值模拟结果、修正公式计算结果,验证该公式的可靠性。结果表明,利用修正公式计算的电阻与实验值相比相对偏差为4.43%,对比数值模拟结果的相对偏差3.51%,但节约了计算时间,该公式可用于指导工程设计。 相似文献