共查询到19条相似文献,搜索用时 171 毫秒
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热声发动机驱动的脉管制冷机是一种完全无运动部件的低温制冷机,具有非常好的应用前景,本文介绍了本实验室在这方面取得的最新进展。首先我们对驻波热声发动机进行了改进设计,提高了其驱动压比,用氦气作为工质最大压比达到了1.15。在此基础上我们用其驱动同轴双向进气小孔型脉管制冷机,通过调整热声发动机的振荡频率,使之与脉管达到匹配,最终达到了84.3K的最低制冷温度,这也是目前用驻波热声发动机驱动脉管所达到的最低制冷温度。同时,在此实验过程中,一些抑制跳频的方法也得到了实验验证。 相似文献
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从描述囚禁离子与驻波激光场相互作用的Jaynes-Cummings(J-C)模型出发,导出了囚禁离子谐振动单量子共振激发相互作用的非线性J-C模型。通过求解这一模型下系统态和离子系统熵的演化规律,数值研究了囚禁离子的熵演化与Lamb-Dick参数 、离子在驻波激光场中的位置以及初始声子强度之间的关系。结果表明,离子熵的演化呈现非周期性的振荡。随着参数 的增大,囚禁离子熵演化的振荡频率变大,囚禁离子内外自由度退纠缠的时间变短。当离子质心的位置从驻波激光场的波节移向波腹,囚禁离子熵演化的振荡频率变小,离子与声子自由度退纠缠的时间变长。如果初始声子场强度较小,离子熵随时间的演化强烈地表现为不规则的振荡,且振荡频率较大;随着初始声子场强度变大,离子熵的演化类似于J-C模型中的场熵演化,不规则的振荡频率逐渐变小。 相似文献
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The flow field and the energy transport near thermoacoustic couples are simulated using a 2D full Navier-Stokes solver. The thermoacoustic couple plate is maintained at a constant temperature; plate lengths, which are "short" and "long" compared with the particle displacement lengths of the acoustic standing waves, are tested. Also investigated are the effects of plate spacing and the amplitude of the standing wave. Results are examined in the form of energy vectors, particle paths, and overall entropy generation rates. These show that a net heat-pumping effect appears only near the edges of thermoacoustic couple plates, within about a particle displacement distance from the ends. A heat-pumping effect can be seen even on the shortest plates tested when the plate spacing exceeds the thermal penetration depth. It is observed that energy dissipation near the plate increases quadratically as the plate spacing is reduced. The results also indicate that there may be a larger scale vortical motion outside the plates which disappears as the plate spacing is reduced. 相似文献
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Thermoacoustic refrigerators have been developed during the last 15 years, employing quasi-standing resonant acoustic waves inside fluid-filled cavities to transfer heat along a stack region. Because higher efficiency can be reached when a significant travelling wave component exists in the resonator, specific resonant thermoacoustic devices have been designed allowing to adjust more or less the ratio of travelling and standing wave components. However, the acoustic pressure field and the particle velocity field do not appear to be the optimal ones, for the thermal quantities of interest. Thus, it is the aim of the paper to present a new kind of thermoacoustic standing wave-like device which allows to control easily and independently the pressure field and the particle velocity field, after investigating the optimal acoustic field, in the stack region, for the main parameters of interest, i.e. the temperature gradient, the thermoacoustic heat flow and the coefficient of performance. 相似文献