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王勤何巍王世宽郝楠徐象国陈光明徐璐陈达 《工程热物理学报》2014,(6):1053
本文搭建了带溶液泵的循环实验装置,并进行了提升管直径分别为6 mm、8 mm和12 mm的气泡泵用于输送12.5%、15%和17.5%三个质量浓度R134a-DMF溶液的性能实验。结果表明,在相同的R134a浓度下,三种管径气泡泵的气相流量随着输入功率的增加均呈大致线性增加趋势,提升效率随着气相流量的增加均明显减少,发生温度均随着输入功率的增加而线性增加,而输入功率对系统压力的影响不大。在相同的R134a浓度和相同气相流量下,8 mm管径气泡泵的提升效率最高,6 mm管径气泡泵的提升效率最低,R134a的浓度对提升效率的影响不明显。随着提升管直径的增大,气泡泵的启动加热量在所有R134a浓度下均增加,R134a的浓度对发生温度的影响不明显,但对系统压力的影响很大。这些实验结果对扩散吸收制冷系统的气泡泵设计具有重要参考价值。 相似文献
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为了进一步提高能源利用效率和实现其空冷化,在双效溴化锂吸收式制冷系统中利用两级气泡泵代替溴化锂吸收制冷系统中传统的机械溶液泵。本文重点对两级溴化锂气泡泵的泵起时间及其影响因素做相关的实验研究,并得出以下的主要研究结果:1)对于不同的管径,两级气泡泵的泵起时间随着加热功率、浸没高度、工质浓度的变化趋势是基本一致的;2)加热功率越大越有利于气泡泵的泵起;3)随着浸没高度的增大气泡泵的泵起时间逐渐减小;4)工质浓度的增大也会使气泡泵的泵起时间增大,但当溴化锂溶液浓度大于54%后影响不明显;5)一级气泡泵的气液成分及中间溶液的闪发一定程度上影响两级气泡泵的泵起时间,因而造成局部区域与上述规律的偏离。 相似文献
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We report the observation of a novel nonlinear optoacoustic phenomenon, that we name forward stimulated interpolarization scattering. When two frequency-offset laser signals are colaunched into orthogonally polarized guided modes of a birefringent small-core (1.8 μm diameter) photonic crystal fiber, a pattern of axially moving polarization fringes is produced, with a velocity and spacing that depends on the frequency offset. At values of frequency offset in the few-GHz range, the pattern of moving fringes can perfectly match the phase velocity and axial wavelength (3.9 mm) of the torsional-radial acoustic mode tightly guided in the core. An intense optoacoustic interaction ensues, leading to efficient nonlinear exchange of power from the higher frequency (pump) mode to the orthogonally polarized lower frequency (Stokes) mode. A full-vectorial theory is developed to explain the observations. 相似文献
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A novel shooting method with excellent simple control strategy is developed for solving the failure to convergence of the traditional shooting methods themselves in fiber lasers model. Compared with the published literature, the novel shooting method provides a clear physical understanding method for getting the threshold pump power and the exact results with given random functions in Yb3+-doped fiber lasers and Er3+-doped fiber lasers. Then, the results in Er3+-doped fiber lasers and Yb3+-doped fiber lasers demonstrate that the solutions using the novel shooting method has high accuracy of 10−8 W with several iteration steps, which have extended the applicable range of the end-pumped power even lower than 1 mW pump power. Furthermore, compared with 1480 nm pump for the threshold and slope efficiencies of the Er3+-doped fiber lasers, 978 nm fiber lasers can extend wider scope of application and be pump source in the coming future. Finally, the lower threshold and higher slope efficiency at 975 nm than those of 910 nm pump in Yb3+-doped fiber lasers, 975 nm pump laser provides for broad band excellent cladding pump source. 相似文献
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研究了带有圆孔的平板附近气泡动力学特性. 基于不可压缩势流理论, 建立了平板圆形破口附近气泡运动数值模型, 并针对气泡初始位置距离破口很近而导致计算结果发散的数值缺陷, 采用气泡壁和壁面融合的方法, 将流场分离为两个半无限域问题进行求解, 实现了在不同无量纲参数范围内的数值模拟, 数值结果与实验结果符合良好. 通过对圆孔附近气泡运动特性的研究发现, 圆孔对气泡的影响基本与壁面相反, 在膨胀阶段对气泡产生腔吸作用, 收缩阶段产生排斥, 在特定的工况下会产生对射流现象. 最后分析了气泡壁与壁面融合, 流场分离后的气泡动态特性以及各工况参数对其影响规律.
关键词:
气泡
边界元
射流
圆孔 相似文献
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根据含损耗系数的稳态速率方程组,对掺准二能级稀土粒子光纤激光器的泵浦阈值进行了分析和完全解析求解。求得了泵浦阈值功率的显函数解析式,得到了泵浦光阈值功率随光纤位置变化的隐函数表达式,以及信号光功率和上能级粒子数随光纤位置变化的解析表达式。对所得的解进行了数值分析,并与已有的理论和实验结果进行了比较分析。结果表明:由于忽略了信号光和泵浦光损耗系数,不同近似条件下给出的泵浦阈值功率均比实验值低,但所导出的理论研究结果与已有实验结果的差异最小。 相似文献