共查询到19条相似文献,搜索用时 125 毫秒
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《节能技术》2016,(3)
在非能动核电站当中,PRHR(非能动余热排出,Passive Residual Heat Removal)是非能动安全系统的重要组成,是事故后、尤其是全厂断电事故后,用于载出堆芯衰变热的重要途径。在高度比例降低的整体试验中,要保证PRHR中的现象与原型的相似性,需要通过理论分析和推导,从理论上证明模拟的准确性,并得到相关的设计准则,才能保证整体试验结果的准确性。通过对事故进程中PRHR主要物理过程和现象进行识别和分析,并进行PRHR的比例分析,得到PRHR在整体试验台架进行事故模拟过程时所需满足的关键比例准则。对不同缩比尺度的比例分析和失真评价结果表明,缩比台架中PRHR的相似准则不能同时得到满足,需要根据试验目的进行选择和取舍;台架整体的高度比(长度比)越接近1,则失真越小。 相似文献
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钢管外包钢筋混凝土在内水压力作用下,限裂设计的准则中,裂缝开展宽度的计算是一关键问题,但一直未解决.本文从考虑径向压力的观点,以粘结滑移理论推导了新公式,本公式适宜于曲杆和坝内埋管及输水管道的裂缝宽度计算,因而有普遍意义和经济意义.从混凝土开裂后钢筋应力增量观点,提出了合适的配筋率,指出只要强度满足则裂缝宽度可不进行计算,以简化设计.讨论了混凝土开裂截面的必然位置,提出不连续配筋的经济合理方案,同时也讨论了设计安全系数的计算方法. 相似文献
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对汽轮发电机组-基础系统模化过程的动力特性相似准则关系进行研究,作者根据相似理论,分别采用量纲分析法和方程分析法建立了模型和原型之间的动力特性相似准则关系。依据相似准则关系,设计并建立了某电厂600MW汽轮发电机线-基础系统的1:20模型,并对该模型进行了模态试验和动力响应试验等动力特性研究工作;根据模型和原型之间的动力特性相似准则关系,推算出该汽轮发电机组-基础系统原型的动力特性参数,从而达到了研究汽轮发电机组-基础系统动力特性的目的。 相似文献
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流化床的放大效应十分显著,使得流化床的试验研究在大型工业流化床设计中的应用发生问题。近年来在国外发展起来的流化床模拟放大技术是从流态化现象的基本控制方程出发,根据相似原理导出一组无量纲相似准则数。这些准则数建立了不同条件下(结构尺寸、温度、压力和床料特性等)的流化性能间相似的内在关系,对流化床的试验研究及设计实践有重要的指导意义及应用前景。 相似文献
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以鹰式二号波浪能发电装置为研究对象,基于捕获宽度达到最优为准则,通过对波浪中运动的装置建立频域运动方程,计算装置运动模态响应、获得最优负载阻尼和主要结构点受力等设计要素,并根据万山岛海域波浪条件开展能量转换系统负载设计、提供结构强度设计支持数据等。研究结果表明:在不同波况下装置获得捕获宽度对应的最优阻尼也不同;鹰式二号波浪能装置对于周期约2 s小周期波浪也具有良好的响应,捕获宽度达50%以上,在主要设计波况3~6 s最高捕获宽度达到300%,在万山岛海域波浪能试验场波况最高捕获宽度达到200%。 相似文献
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Nuclear vendors and utilities perform numerous simulations and analyses in order to ensure the safe operation of nuclear power plants (NPPs). In general, the simulations are carried out using vendor-specific design codes and best-estimate system analysis codes, most of which were developed based on one-dimensional lumped parameter models. During the past decade, however, computers, parallel computation methods, and three-dimensional computational fluid dynamics (CFD) codes have been dramatically enhanced. The use of advanced commercial CFD codes is considered beneficial in the safety analysis and design of NPPs. The present work analyzes the flow distribution in the downcomer and lower plenum of Korean standard nuclear power plants using STAR-CD. The lower plenum geometry of a pressurized water reactor (PWR) is very complicated, as there are many reactor internals, which hinders CFD analysis for real reactor geometry up to now. The present work takes advantage of 3D CAD model so that real geometry of a PWR is used. The results give a clear figure about flow fields in the downcomer and lower plenum of a PWR, which is one of major safety concerns. The calculated pressure drop across the downcomer and lower plenum appears to be in good agreement with the data in engineering calculation. An algorithm that can evaluate the head loss coefficient, which is necessary for thermal-hydraulic system code running, was suggested based on these CFD analysis results. 相似文献
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水煤浆气化炉激冷室内合成气穿越液池过程是复杂的气液固三相的流动过程,该过程起到合成气的进一步冷却及其所含凝渣捕集的作用。将欧拉和拉格朗日方法相结合,用VOF模型跟踪气液界面,用直接模拟蒙特卡罗方法(DSMC)计算颗粒碰撞。对含渣气体穿越液池的气液固三相流动过程进行了数值模拟,探讨了不同粒径、气流速度以及下降管出口淹没深度对气液流场以及对固体颗粒分离的影响。研究表明:气体出下降管后做流动方向急剧突变的流动,穿越过程气液形成具有一定周期的波状流动;含尘气体穿越液池过程对颗粒具有较高的捕集效率;颗粒的捕集效率随着粒径的增大而提高;随着气流出流速度以及下降管出口淹没深度的增加,液体的扰动加强,产生更多的液滴,有助于颗粒捕集效率的提高,但气流速度及淹没深度对颗粒捕获效率的影响逐渐减弱。 相似文献
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Yong Sung Kim Sylvie Lorente Adrian Bejan 《International Journal of Heat and Mass Transfer》2009,52(9-10):2362-2369
This paper shows that the architecture of a steam generator for a power plant can be deduced on the basis of the constructal law. According to constructal theory, the flow architecture emerges in time such that it provides progressively greater access to its currents. The circulation of water is driven by buoyancy in one large tube (the downcomer) and many parallel smaller tubes (the riser). The total flow volume is fixed. Two flow models are used: single phase liquid in the downcomer and riser, and liquid–vapor mixture in the riser tubes. Features that result from constructal design are: the tube diameters, the number of riser tubes, the water circulation rate, the rate of steam production, and how the flow architecture should change when the operating pressure and the size of the flow system change. 相似文献
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通过对锅筒下降管相贯环焊缝裂纹原因的分析,采取了相应的改进措施。结果表明,措施是得当的。取得了良好的效果。 相似文献
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This study shows that the main features of a steam generator can be determined based on the method of constructal design. The generator is endowed with freedom to morph, and then is optimized by putting the right components in the right places. The number of steam tubes is sufficiently large, so that the steam generator may be modeled as continuous. The total volume of the assembly and the volume of the steam tubes are fixed. The geometry is free to vary in the search for maximum heat transfer density. The steam flow in the tubes is modeled in two ways: single‐phase and two‐phase fully developed turbulent flow. Results of the analysis are: the location of the flow reversal (i.e. the demarcation between the tubes of the downcomer and those of the riser), the optimal spacing between adjacent tubes, and the number of tubes for the downcomer and the riser. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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《International Journal of Pressure Vessels and Piping》2001,78(2-3):185-196
The APEX Test Facility at Oregon State University has been modified to simulate a typical 2×4 loop Combustion Engineering nuclear plant. The new configuration, APEX-CE, will be used to perform a series of separate effects and integral systems overcooling tests that examine the conditions that lead to primary loop stagnation and cold leg thermal stratification. RELAP5 calculations will be compared to the test data to assess its ability to predict the onset of loop stagnation. A computational fluid dynamics (CFD) code will be assessed against the APEX-CE cold leg and downcomer fluid mixing data. This work is part of the US nuclear regulatory commission's (USNRC) effort to review its existing pressurized thermal shock (PTS) guidance. 相似文献
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探讨下降管自悬吊结构的设计方法,利用CaesarⅡ应力分析软件对其进行分析,并采用增加下降管壁厚和增加导向的方法解决局部应力超标问题。 相似文献