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Thomas Höhne Deendarlianto Dirk Lucas 《International Journal of Heat and Fluid Flow》2011,32(5):1047-1056
In order to improve the understanding of counter-current two-phase flows and to validate new physical models, CFD simulations of 1/3rd scale model of the hot leg of a German Konvoi PWR with rectangular cross section was performed. Selected counter-current flow limitation (CCFL) experiments at the Helmholtz–Zentrum Dresden–Rossendorf (HZDR) were calculated with ANSYS CFX 12.1 using the multi-fluid Euler–Euler modeling approach. The transient calculations were carried out using a gas/liquid inhomogeneous multiphase flow model coupled with a k-ω turbulence model for each phase. In the simulation, the surface drag was approached by a new correlation inside the Algebraic Interfacial Area Density (AIAD) model. The AIAD model allows the detection of the morphological form of the two phase flow and the corresponding switching via a blending function of each correlation from one object pair to another. As a result this model can distinguish between bubbles, droplets and the free surface using the local liquid phase volume fraction value. A comparison with the high-speed video observations shows a good qualitative agreement. The results indicated that quantitative agreement of the CCFL characteristics between calculation and experimental data was obtained. The goal is to provide an easy usable AIAD framework for all Code users, with the possibility of the implementation of their own correlations. 相似文献
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traditional package method of a yellow phosphor with a blue chip. However, its light efficiency needs to be further improved for the use of backlights for LCDs. 相似文献
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背光组件中主要的发光器件冷阴极荧光灯(CCFL)具有特定的电气特性,通过实验研究了CCFL的与发光亮度和发光效率有关的特性,定性地分析了CCFL的自激振荡电路的工作原理。并在此基础上,对逆变振荡电路进行了定量的理论分析,为设计高效率驱动电路提供参考依据。 相似文献
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脉宽调制亮度调节方式下冷阴极荧光灯性能的实验研究 总被引:2,自引:1,他引:1
从电学的角度看,由于冷阴极荧光灯(Cold cathode fluorescent lamp,CCFL)具有十分复杂的阻抗特性,例如,灯管的阻抗几乎随工作电流的增加而减小,因此对其亮度进行调节也十分困难,尤其是大亮度调节比的场合。在对逆变电路进行优良设计并进行同步调光的前提下,脉宽调制(Pulse width modulating,PWM)可以实现高达2000:1的亮度调节比。这种大范围亮度调节特性,可以满足机载显示器的亮度调节性能要求。另一方面,CCFL的亮度输出与PWM的占空比之间具有良好的线性关系。此外,还不会对CCFL的寿命造成任何的影响,从而保证了军用显示器件的可靠性。实验结果表明,PWM方式可以很好地调节多管并列式背光灯组的亮度,这是其他调节方式无法做到的。 相似文献
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用四种方法合成发红光的小颗粒 Y2O3:Eu 荧光粉,并将其加入到白光的三元化合物荧光粉中,可来制作高亮度、亚微型的 CCFLs 并运用在 LCD 显示器的背光源领域.连续的工艺流程使得大规模的制造成为可能. 相似文献
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特种液晶显示器对背光源提出特殊要求。介绍了特种液晶显示器用背光源的主流类型CCFL(冷阴极荧光灯)和LED(发光二极管)。从亮度、功耗、色彩、可靠性等方面详细讨论了各自的技术特点。分析了LED背光源在特种液晶显示器技术中的重要地位。 相似文献
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背光源的发展趋势(第一部分) 总被引:1,自引:1,他引:0
介绍了LCD背光源的市场及技术的发展。LCD已广泛用于手机、计算机显示器、笔记本电脑,目前正在冲击TV市场,预计LCD的快速增长将持续到2010年。因此LCD背光源模组也会得到快速增长。
讨论了带有CCFL、EEFL、HCFL以及LED的背光源。扫描型HCFL背光源可改善LCDs的图像质量,LED背光源则可获得大的色域,但是它们的功耗仍然大于CCFL,而且成本也很高。 相似文献