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关于浮力问题,初中阶段只讨论了流体在静止状态下的浮力,并给出了此时浮力计算公式F浮=ρ液gV排;高中物理教材中并没有专门讨论浮力问题,但是在讨论超重和失重状态时常会和浮力联系在一起,那么在超重和失重状态下浮力怎样计算呢?同学们是否能运用初中所学的知识解决新的问题呢?下面我们就利用初中和高中所学知识帮助同学们推导超重和失重情况下的浮力计算公式,并利用它讨论一些与超重、失重有关的浮力问题. 相似文献
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研究了高功率激光在封闭通道传输时,空气吸收激光能量引发的浮力对流对热晕效应的影响。建立了浮力对流下热晕效应的物理模型,采用数值计算方法分析了热传导和对流传热这两种影响光束质量的因素,发现浮力对流对封闭通道内热晕效应有削弱作用,并且会造成光束质心漂移。研究了不同排布方式下阵列光束的远场光斑形状、光束质量和光斑质心漂移。结果表明,阵列光束间相互作用下的浮力对流更强,对热晕效应的削弱作用更强,不同排布方式下不同位置处光束的情况不同,通过选择合适的排布方式可以找到优化的光束质量和质心漂移。验证了利用轴向风可以抑制热晕效应的方法,结果表明浮力对流的存在会促进热晕效应的减弱,当轴向风逐渐增大时,热晕逐渐被抑制,浮力对流的影响逐渐消失。 相似文献
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悬浮力是高温超导磁悬浮列车运行中的一个至关重要的参数.悬浮力的弛豫特性是高温超导磁悬浮列车安全运行的一大阻碍.适度降低工作温度是有效改善悬浮力弛豫特性的有效手段之一.本文从数值计算和实验两个层面研究了不同冷却温度和不同场冷间隙下的悬浮力的弛豫现象.发现悬浮力的弛豫现象随着超导块冷却温度的降低而减弱,随着场冷间隙的增大而略微增大,但是随着冷却温度的降低,增大程度会有所减弱.该研究有助于通过合理设计高温超导材料工作温度,以提高磁悬浮系统性能表现. 相似文献
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在考虑空气浮力和阻力情况下,对垂直下落物体运动进行了分析.通过数值计算的方法,对比萨斜塔铁球下落及雨滴下落两个运动进行了描述. 相似文献
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本文在前人研究的基础上,计入浮力、表面张力、不同流体密度比等因素对弹性膜附近气泡运动的影响,结合不可压缩理想流体理论,建立气泡与弹性膜耦合动力学数值模型,采用边界元方法进行求解,计算值与Turangan等的实验结果符合良好.通过对弹性膜附近气泡运动的数值模拟,详细分析了弹性膜两侧为同种密度液体以及不同密度液体时气泡的运动,随后又分析气泡在弹性膜和浮力的共同作用下气泡的射流特性.旨在为相关气泡与弹性膜相互作用特性的研究提供参考.
关键词:
弹性膜
边界元法
气泡
浮力 相似文献
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针对超导球体和圆形线圈之间的力的作用,介绍了一种简化而有效的计算悬浮力的方法。在此基础上,对线圈和超导球体的几何形状尺寸以及两者之间的相对位置关系对悬浮力的影响进行了综合的分析和讨论;对悬浮力在随着线圈和超导球体的具体参数的变化规律做了定量的分析。总结出的结论为超导悬浮系统的分析和设计提供重要的参照。 相似文献
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本文利用数值模拟研究了浮力对湍流预混V形火焰平均速度场的影响,发现浮力效应主要体现在远场区域,而在火焰刷附近非常有限;利用落塔和 OH-PLIF 方法在正常重力和微重力下观测了火焰皱褶,发现浮力压制火焰皱褶的程度与湍流强度密切相关。分析表明斜压机理是浮力影响火焰皱褶的重要原因。 相似文献
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Abstract Results are presented that illustrate the effect of augmenting or opposing thermal and solutal body forces on the flow, temperature and concentration distributions. For augmenting buoyancy forces, the flow field is very similar to that for a single-component fluid. Multicellular flow patterns are observed for opposing buoyancy forces that depend on the buoyancy parameter. The solutal buoyancy force does not dominate the flow field for all values of opposing body forces, because the solutal gradient is vertical. The concentration gradient affects the natural convection through both the additional buoyancy force and the thermophysical properties of the gas mixture. 相似文献
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针对学生难以理解和掌握液体浮力产生原因的问题,利用烧杯、石蜡等简易材料设计并制作了液体浮力演示装置.该实验装置可以通过控制烧杯中石蜡上下表面受到液体压力来操纵石蜡的沉浮,进而演示出浮力的实质. 相似文献
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Kyu Ho Van Jeong Park Sung Hwan Yoon Suk Ho Chung Min Suk Cha 《Proceedings of the Combustion Institute》2019,37(2):1997-2004
The oscillating lifted flame in a laminar nonpremixed nitrogen-diluted fuel jet is known to be a result of buoyancy, though the detailed physical mechanism of the initiation has not yet been properly addressed. We designed a systematic experiment to test the hypothesis that the oscillation is driven by competition between the positive buoyancy of flame and the negative buoyancy of a fuel stream heavier than the ambient air. The positive buoyancy was examined with various flame temperatures by changing fuel mole fraction, and the negative buoyancy was investigated with various fuel densities. The density of the coflow was also varied within a certain range by adding either helium or carbon dioxide to air, to study how it affected the positive and negative buoyancies at the same time. As a result, we found that the range of oscillation was well-correlated with the positive and the negative buoyancies; the former stabilized the oscillation while the latter triggered instability and became a source of the oscillation. Further measurements of the flow fields and OH radicals evidenced the important role of the negative buoyancy on the oscillation, detailing a periodic variation in the unburned flow velocity that affected the displacement of the flame. 相似文献
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为了弥补现行教科书中浮力产生原因的知识呈现的不足,设计了符合学生认知规律的正方体显压浮子实验装置.该装置的特征是通过“U”型压强计系统能够在正方体上直接显示上下表面所受压强不同,从而形象地表明浮力产生的原因. 相似文献
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The onset and stability of solutal (buoyancy and Marangoni) convection induced by a localized source of surface-active substance
placed under an interface were studied both experimentally and theoretically. It was shown that the competition between the
buoyancy and solutocapillary convection can lead to the onset of oscillatory convection. The period of the observed oscillations
appreciably depends on the relation of Grashof and Marangoni numbers and on the aspect ratio of the geometrical sizes of the
problem. It was found out that an increase of the buoyancy contribution leads to the onset of stationary convection instead
of oscillatory one. 相似文献
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水中工作固体火箭发动机处于重浮力同时作用环境下, 与工作于大气环境下的固体火箭发动机具有不同的工作特性. 为进一步掌握水下固体火箭发动机的工作特性, 对具有重浮力特征的水下射流进行研究, 重点分析重浮力作用下水平喷射射流结构及推力振荡情况, 采用VOF模型对水平喷射且具有重浮力特征的三维发动机模型进行仿真模拟, 对比有/无重浮力下射流气泡的上浮特征, 并采用动量原理对发动机工作初期的射流扰动进行分析, 获得了重浮力下水下固体火箭发动机的推力振荡特征. 研究结果表明: 由于重浮力逐渐占据主导地位, 射流气泡具有明显的上浮特征, 推力与重浮力耦合后在竖直方向产生的翻转力矩更大, 通过与文献中实验对比可见, 采用VOF模型并考虑重浮力后仿真所得射流结构与实验结果更吻合. 相似文献
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Effects of interstitial air on the motions of a large intruder in a shaken granular bed are studied experimentally as a function of ambient air pressure, particle size of the bed, and the density of the intruder. It is found that the intruder always rises from the granular bed in the absence of air. However, the intruder can acquire both positive and negative buoyancy in the presence of air. Negative buoyancy can be observed only when both the density of the intruder and the particle size of the bed are small enough. This negative buoyancy can be explained by the unusual air pressure distribution found in the bed. 相似文献