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胡效东王灏王世飞张景坡曾庆良 《振动与冲击》2017,(14):133-137
针对某型号搅拌反应器搅拌主轴因振动断裂的问题,基于流固耦合理论,采用CFD和FEM相结合的单向耦合稳态的数值模拟以及经验公式计算方法。在考虑流场作用的条件下分析多种方法得出搅拌器的临界转速结果。分析主轴断裂的原因及影响搅拌器的固有频率的流体因素,并对主轴结构进行改进。得出结论:主轴驱动电机转速大于主轴的最低设计转速是主轴产生振动断裂的主要原因;搅拌介质的流体力和阻尼作用对搅拌器的固有频率均有影响;可以将主轴适当加粗以提高其临界转速,从而远离共振范围并有效解决振动问题;采用流固耦合的方法能够考虑搅拌器转动、流体载荷和搅拌桨叶的影响。其计算结果比经验公式更接近实际情况。 相似文献
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《振动与冲击》2017,(14)
针对某型号搅拌反应器搅拌主轴因振动断裂的问题,基于流固耦合理论,采用CFD和FEM相结合的单向耦合稳态的数值模拟以及经验公式计算方法。在考虑流场作用的条件下分析多种方法得出搅拌器的临界转速结果。分析主轴断裂的原因及影响搅拌器的固有频率的流体因素,并对主轴结构进行改进。得出结论:主轴驱动电机转速大于主轴的最低设计转速是主轴产生振动断裂的主要原因;搅拌介质的流体力和阻尼作用对搅拌器的固有频率均有影响;可以将主轴适当加粗以提高其临界转速,从而远离共振范围并有效解决振动问题;采用流固耦合的方法能够考虑搅拌器转动、流体载荷和搅拌桨叶的影响。其计算结果比经验公式更接近实际情况。 相似文献
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《中国新技术新产品》2016,(7)
为了使流体得到有效的搅拌混合,需要考虑多种因素,如搅拌器位置、结构、转速、反应釜容量、流体物性、粘度等。本文仅针对流体粘度的变化情况,简要阐述了不同的搅拌器结构及其适用范围,为在实际生产生活中选择合适构型的搅拌器,以达到较好的搅拌效果提供一定的参考。 相似文献
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转子存在偏心距时,弯曲振动和扭转振动之间会相互作用产生弯扭耦合振动。目前对弯扭耦合振动的研究主要集中于其非线性特征,针对共振振幅大小和共振影响因素等共振特征的研究却比较少见。在实际的结构设计工作中,有时要利用耦合共振获取更大的振幅和振动能量。所以有必要从共振特征入手,对转子的弯扭耦合振动开展进一步的研究。首先建立偏心转子的弯扭耦合振动模型,使用小参数法对振动方程求解。其次分析扭转振动、弯扭振动产生耦合共振的条件,详细比较各振型共振振幅的大小和各参数对共振振幅的影响。然后以具体的算例,对各参数对弯扭耦合共振振幅大小的影响进行数值模拟,计算各阶共振振幅的大小,给出具有最大共振振幅时的参数条件,验证理论分析,为弯扭耦合振动的研究工作提供思路和依据。 相似文献
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反应器是化工生产中的核心设备,它的型式常见的有管式、塔式、釜式,其中最为普遍的是搅拌反应釜。搅拌反应釜广泛应用于染料、医药、试剂、食品及合成材料等工业工艺生产过程中的混合、传质、传热等,它通常由釜体、搅拌器、传动装置及轴封装置等组成。 相似文献
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利用颗粒离散元对深厚砂性土地基进行共振致密模拟与机理分析,详细地研究了高频共振致密过程中,土体内部孔隙率、位移、孔隙水压力的变化情况,以及振动杆杆端及杆周土体的力学特性;对振动频率、振幅及颗粒级配对共振致密效果的影响进行了分析。结果表明:高频共振致密能很好地用于处理深厚粉砂土地基,振动结束后,土体的孔隙率明显减小,表层位移明显,振动杆杆端及杆周的土体力学特性也发生较大变化;共振致密的效果受振动杆振幅、频率及土体级配状况等因素的影响,振幅和频率过大或过小都无法获得最佳致密效果。在实际工程中,应根据土体的特性确定最佳的振幅和频率。 相似文献
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滚动轴承常常在复杂工况下工作,当滚动轴承出现局部故障时,其振动信号中除了与故障信息相关的周期性瞬态冲击成分外,还包含轴转频等谐波成分和背景噪声。因此,在滚动轴承故障早期,对滚动轴承振动信号直接进行包络解调分析往往效果不佳。针对上述问题,提出了基于最优品质因子信号共振稀疏分解的滚动轴承故障诊断方法。该方法首先以信号共振稀疏分解低共振分量的峭度最大为目标,利用遗传算法对信号共振稀疏分解方法的品质因子进行优化,得到最优品质因子;然后利用最优品质因子对轴承振动信号进行信号共振稀疏分解,得到高共振分量和低共振分量;最后对低共振分量进行希尔伯特解调分析,提取轴承故障特征频率,进而诊断滚动轴承故障。仿真信号和试验信号的分析结果表明,该方法能有效提取轴承故障振动信号中的冲击成分,诊断轴承故障。 相似文献
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H. Puga J.C. Teixeira J. Barbosa E. Seabra S. Ribeiro M. Prokic 《Materials Letters》2009,63(24-25):2089-2092
The combined effect of high intensity ultrasound and melt stirring on the degassing of AlSi9Cu3 using simultaneously the novel MMM (Multi-frequency Multimode Modulated) ultrasonic technology to promote cavitation, and low frequency mechanical vibration to induce melt stirring, was studied. On a first stage single low frequency mechanical vibration experiments were carried out in water in order to visualize and characterize its individual effect on the liquid dynamics. On a second stage ultrasonic vibration combined with different mechanical vibration frequencies, melt temperatures and processing times were tested in liquid AlSi9Cu3 alloy and their influence on the degassing efficiency was evaluated and compared with the results of the single MMM ultrasonic degassing technique. Fixed ultrasonic parameters (frequency and electric power) were used, according to the best results obtained in former experimental works developed by the authors. For the experimental conditions used in this research, it was found that melt stirring significantly improves degassing efficiency, and such improvement depends on the metal temperature and the mechanical vibration frequency. The experimental results suggest that combining melt agitation and ultrasonic vibration it is possible to achieve almost the aluminum alloy theoretical density without increasing the processing time. 相似文献
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A kinetic study of molasses wastewater ozonation was carried out in a stirred tank reactor to obtain the rate constants for the decolorization reaction and the regime through which ozone is absorbed. First, fundamental mass transfer parameters such as ozone solubility, volumetric mass transfer coefficients and ozone decomposition kinetics were determined from semi-batch experiments in organic-free solutions with an ionic composition similar that of industrial wastewater. The influence of operating variables such as the stirring rate and gas flow rate on the kinetic and mass transfer parameters was also studied. The application of film theory allows to establish that the reactions between ozone and colored compounds in wastewater take place in the fast and pseudo-first-order regime, within the liquid film. The decolorization rate constants were evaluated at pH 8.7 and 25 degrees C, varying from 0.6 x 10(7) to 3.8 x 10(7)L mol(-1)s(-1), depending on the stirring rate and the inlet gas flow. 相似文献
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首先对燃料电池发动机反应堆进行初步设计,然后建立燃料电池发动机反应堆悬置系统振动力学模型,同时对反应堆悬置系统进行振动特性分析,最后采用移频减振原理对燃料电池发动机反应堆悬置刚度和阻尼进行优化设计;设计方法可以达到对燃料电池发动机反应堆进行隔振的设计要求。 相似文献
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目的探讨包装容器的扫频特性以及随机激励下的频域和时域特征,讨论不同内容物对包装容器振动特性的影响。方法针对液体、固体不同内容物对包装容器进行扫频和随机振动试验,以振动强度,内容物体积为变量对比分析不同容器加速度响应,频域分布特点和响应能量。结果在扫频试验中,内容物为固体时,共振频率集中在50 Hz附近;内容物为液体时,当其体积占包装容器总容积体积的比值为50%、80%时,容器一阶共振频率在20 Hz附近。在随机试验中,内容物为液体时包装容器响应加速度功率谱密度分布较固体时分散,加速度响应能量整体较固体大,在内容物占包装总容积体积的比值为50%时响应能量最大,激励强度增加对内容物为液体的包装容器响应影响明显,正态分布能很好地描述了包装容器的随机振动响应时域分布;内容物为液体时加速度响应分布与高斯分布偏离明显。结论内容物不同会造成包装容器共振频率、响应加速度、功率谱密度分布等的显著差异。 相似文献
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It is a difficult job to gauge the liquid fuel mass in a tank on spacecrafts under microgravity condition. Without the presence of strong buoyancy, the configuration of the liquid and gas in the tank is uncertain and more than one bubble may exist in the liquid part. All these will affect the measure accuracy of liquid mass gauge, especially for a method called Compression Mass Gauge (CMG). Four resonance resources affect the choice of compression frequency for CMG method. There are the structure resonance, liquid sloshing, transducer resonance and bubble resonance. Ground experimental apparatus are designed and built to validate the gauging method and the influence of different compression frequencies at different fill levels on the measurement accuracy. Harmonic phenomenon should be considered during filter design when processing test data. Results demonstrate the ground experiment system performances well with high accuracy and the measurement accuracy increases as the compression frequency climbs in low fill levels. But low compression frequencies should be the better choice for high fill levels. Liquid sloshing induces the measurement accuracy to degrade when the surface is excited to wave by external disturbance at the liquid natural frequency. The measurement accuracy is still acceptable at small amplitude vibration. 相似文献
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Gold nanorods have been prepared by the seed-mediated growth method, in order to find the effect of stirring during the synthesis to the final shape and optical properties. The presence or absence of stirring during each step of the preparation procedure was considered a parameter to control in order to adjust the optical absorption associated with the surface plasmon resonance of the nanorods. Results show that the longitudinal surface plasmon resonance band shifts to larger wavelengths in the absence of stirring of the growth solution. Width and intensity of the absorption band associated with the longitudinal surface plasmon is reduced upon stirring during the synthesis. On the contrary, the position of the transversal surface plasmon resonance band scarcely depends upon stirring. Theoretical calculations performed using the Gans model are coherent with experimental obtained results, showing that as the aspect ratio increases, longitudinal plasmons absorption shifts toward larger wavelengths and increases both intensity and bandwidth. 相似文献
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为研究某型采煤机螺旋滚筒振动可靠性,根据实际工况模拟螺旋滚筒的瞬时冲击载荷,建立螺旋滚筒的有限元模型,对其进行振动模态分析,识别出主要模态参数和振型规律,发现截齿部位振动变形明显;建立了螺旋滚筒共振失效准则,结合可靠性灵敏度分析理论和BP神经网络,得到了滚筒结构参数,振动可靠性灵敏度,分析结构参数对振动可靠性的影响。结果表明,螺旋滚筒振动可靠度为0.999549。基于共振失效准则,将协同仿真技术与BP神经网络和可靠性灵敏度分析理论相结合,为采煤机螺旋滚筒的振动特性分析与结构设计提供理论方法和数据支撑。 相似文献
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环形含液容器在以华龙一号、AP1000和CAP1400为代表的第三代核电站中得到普遍应用,其本身的动力特性与动力反应是有待解决的重要安全问题。该文以环形含液系统动力学方程的建立和求解为主要研究目的,基于势流体理论和第二类边界条件的Bessel函数展开,推导环形容器液体小幅振动的振动频率和动液压力响应的理论解。通过极限分析、与试验结果以及与有限元方法对比,验证理论公式的正确性。对环形水箱动力反应问题开展计算,初步分析了环形水箱内外环动水压力反应规律和特点,并与同几何尺寸的圆柱形水箱对比,分析其振动频率与动液压力响应规律的异同。结果表明:由于环形水箱与圆柱形水箱液体振动频率的差异,两者动水压力反应在可引发其中某一模型液体共振的荷载作用下将出现较大差异。该文研究可为环形含液容器的工程应用提供理论支持。 相似文献