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LED板状肋片散热器性能的方向效应 总被引:1,自引:1,他引:0
为考察装配板状肋片散热器的多角度照射型LED灯的自然对流散热性能的方向效应,以一款LED投光灯的关键散热结构为研究对象,采用实验测量法验证数值模拟的计算精度,并将数值模拟的温度和流体数据用于分析3种驱动电流和7个出光倾角下最大温升和温度均匀性的散热机制。结果表明:不同倾角下的散热器肋间风道内的流速分布的较大差异,是导致最大温升和温度均匀性变化的根本原因;最高温度点的上、下游流速的差值可用于定量解释温度均匀性的变化规律。不同倾角下肋片间距对最大温升的影响趋势表明:最佳间距附近的散热器性能对倾角的敏感度最高,散热能力的方向效应不容忽视。 相似文献
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针对HPR1000压水堆堆芯,开展了应用MOX (混合氧化物燃料)组件的燃料管理方案初步研究。对MOX燃料组件进行设计,研究了MOX燃料成分及燃料棒在组件内的布置。在此基础上,开展了1/4堆芯年换料、18个月长周期换料,并装载50%MOX组件这两种燃料管理方案研究。通过与UO2堆芯的对比,分析了装载50%MOX组件堆芯的核特性。分析结果表明,两种50%堆芯装载MOX组件的燃料管理方案,其堆芯主要物理参数均满足核设计准则要求。 相似文献
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燃料组件变形状态是堆芯运行过程中的重要监测指标,基于水下双目视觉的变形检测系统不仅能获得燃料组件关键参数的三维尺寸,还可以测量组件的整体轮廓。根据水下大型燃料组件的高热、高辐射特点,研制了一种基于16台摄像单元的水下双目检测系统,并给出各组成模块的详细设计;通过联合Harris特征点和区域灰度互相关方法,实现辐射噪声干扰下的双目摄像模块的组内快速图像配准。经模拟水池和核电现场实验,验证系统局部参数测量精度优于0.2 mm,全局参数测量精度满足0.5 mm,为高热、高辐射的水下乏燃料组件的局部变形和整体弯曲等参数测量提供有力工具。 相似文献
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发展建立了用于多体分离等包含动边界的非定常流场数值模拟方法,建立了笛卡尔坐标系下边界以任意速度运动的控制体上的流动控制方程,结合几何守恒律确定网格速度,发展了基于结构网格的动网格方法,网格移动量采用加权插值方法得到.通过数值模拟二维翼型及三维机翼的强迫振荡非定常流场,表明该方法可以数值模拟包含动边界的非定常流场. 相似文献
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We introduce boundary adapted wavelets, which are orthogonal and have the same scale in the three spatial directions. The construction thus yields a multiresolution analysis. We analyse direct numerical simulation data of turbulent channel flow computed at a friction Reynolds number of 395, and investigate the role of coherent vorticity. Thresholding of the vorticity wavelet coefficients allows us to split the flow into two parts, coherent and incoherent flows. The coherent vorticity is reconstructed from its few intense wavelet coefficients and the coherent velocity is reconstructed using Biot–Savart's law. The statistics of the coherent flow, i.e. energy and enstrophy spectra, are close to the statistics of the total flow, and moreover, the nonlinear energy budgets of the total flow are very well preserved. The remaining incoherent part, represented by the large majority of the weak wavelet coefficients, corresponds to a structureless, i.e. noise-like, background flow whose energy is equidistributed. 相似文献
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压力管嵌入式燃料部件内冷却剂管道间不存在横向交混,若燃料辐照肿胀或碎片进入冷却管道内,容易引发堵流事故,造成局部冷却条件恶化,使燃料烧毁。考虑到次临界能源包层流动路径长、方向弯曲等特点,针对入口堵流事故提出一种多尺度热工模拟方法,通过RELAP5程序给计算流体力学(CFD)软件提供边界条件,对核功率密度最高的燃料部件入口处第一排单根流道部分堵塞和全部堵塞工况进行数值模拟,分析事故条件下燃料热工安全特性。结果表明:第一排单根流道部分堵塞时燃料温度仍满足安全限值,而全部堵塞时峰值温度将超过燃料相变温度限值。 相似文献
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压力管嵌入式燃料部件内冷却剂管道间不存在横向交混,若燃料辐照肿胀或碎片进入冷却管道内,容易引发堵流事故,造成局部冷却条件恶化,使燃料烧毁。考虑到次临界能源包层流动路径长、方向弯曲等特点,针对入口堵流事故提出一种多尺度热工模拟方法,通过RELAP5程序给计算流体力学(CFD)软件提供边界条件,对核功率密度最高的燃料部件入口处第一排单根流道部分堵塞和全部堵塞工况进行数值模拟,分析事故条件下燃料热工安全特性。结果表明:第一排单根流道部分堵塞时燃料温度仍满足安全限值,而全部堵塞时峰值温度将超过燃料相变温度限值。 相似文献
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Self-organized phenomena of pedestrian counter flow in a channel under periodic boundary conditions
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In this paper we investigate self-organized phenomena such as lane formation generated by pedestrian counter flow in a channel.The lattice gas model is extended to take the effect of walkers in the opposite direction into account simultaneously when they are in the view field of a walker,i.e.,walkers tend to follow the leaders in the same direction and avoid conflicts with those walking towards them.The improved model is then used to mimic pedestrian counter flow in a channel under periodic boundary conditions.Numerical simulations show that lane formation is well reproduced,and this process is rather rapid which coincides with real pedestrian traffic.The average velocity and critical density are found to increase to some degree with the consideration of view field. 相似文献
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以往的实验研究中,已经知道粗糙边界条件下,二维颗粒流的颗粒流量是以通道中心横向对称分布的,颗粒流横向分布既受通道宽度的影响,同时也受通道斜面倾斜角的影响,而且颗粒在通道两侧的分布明显少于通道中间. 主要研究粗糙边界附近颗粒分布随通道宽度以及通道斜面倾斜角的变化规律. 在稀疏流状态以及保持边界墙体的粗糙度不变的条件下,对应不同通道宽度,粗糙边界附近10d范围内的颗粒流量密度(ξ=ρv)随斜面倾斜角的增大而减小,颗粒流量密度随通道宽度的变化存在一临界宽度Wc;在通道宽度小于Wc时,粗糙墙体附近10d范围内颗粒流量密度ξ随sinθ呈指数衰减,通道宽度大于Wc时,颗粒流量密度ξ_sinθ曲线随θ增大几乎呈线性减小.
关键词:
二维颗粒流
颗粒物质
颗粒流量密度 相似文献
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Sangster TC Goncharov VN Radha PB Smalyuk VA Betti R Craxton RS Delettrez JA Edgell DH Glebov VY Harding DR Jacobs-Perkins D Knauer JP Marshall FJ McCrory RL McKenty PW Meyerhofer DD Regan SP Seka W Short RW Skupsky S Soures JM Stoeckl C Yaakobi B Shvarts D Frenje JA Li CK Petrasso RD Séguin FH 《Physical review letters》2008,100(18):185006
The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)10.1016/S0030-4018(96)00325-2]. Neutron-averaged areal densities of 202+/-7 mg/cm2 and 182+/-7 mg/cm2 (corresponding to estimated peak fuel densities in excess of 100 g/cm3) were inferred using an 18-kJ direct-drive pulse designed to put the converging fuel on an adiabat of 2.5. These areal densities are in good agreement with the predictions of hydrodynamic simulations indicating that the fuel adiabat can be accurately controlled under ignition-relevant conditions. 相似文献
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实验研究了粗糙边界条件、不同通道宽度以及不同斜面倾斜角下二维颗粒流的颗粒分布 ,发现颗粒流在稀疏流状态下尽管在现象上表现出类似流体的性质,但由于颗粒流系统的能 量耗散,所以颗粒流的速度和密度分布和牛顿流体完全不同,颗粒流在通道中的分布既受通 道宽度的影响同时也受重力场的影响,颗粒在通道中以通道中轴线呈对称分布,通道两侧的 颗粒密度明显高于通道中间,由于通道中颗粒受剪切力的作用,导致颗粒在通道中的密度分 布的变化,通道边界粗糙度明显影响着颗粒流横向分布.
关键词:
二维颗粒流
颗粒物质
稀疏流 相似文献
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An analytical version of the discrete-ordinates method is used to solve the classical problems of Poiseuille flow and thermal-creep flow in a plane channel. The kinetic theory for the rarefied-gas flow is based on the S model (a generalization of the BGK model), and in addition to the use of the diffuse-specular reflection model (based on a single accommodation coefficient) for describing particle scattering from the channel walls, the Cercignani-Lampis model defined in terms of normal and tangential accommodation coefficients is implemented. The established solution is tested numerically, and results for the velocity and heat-flow profiles, the particle-flow rate and the heat-flow rate thought to be correct to many significant figures are reported for various values of the channel width. 相似文献
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S. P. Medvedev A. N. Polenov S. V. Khomik B. E. Gel’fand 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(1):70-74
The results of studying deflagration-to-detonation transition (DDT) in hydrogen-methane (propane)-air in a detonation tube
with uniformly spaced annular obstacles are presented. The effect of the scaling factor on the DDT was identified. The boundary
between fast deflagration and detonation regimes was calculated using a criterion based on a comparison of the gasdynamic
and chemical characteristic times for the ignition of the mixture behind the shock wave reflected from an obstacle. 相似文献