瞬态流体激励下离心泵转子振动特性研究

以IS型离心泵三维模型为研究对象,采用计算流体动力学方法（CFD）对离心泵进行非定常流场数值模拟,进而得到作用在叶轮上的瞬态流体激振力。同时建立泵转子系统的二维有限元模型,将流体激振力作为外载荷施加在转子动力学模型上,研究了离心泵在不同工况下不平衡质量与所受流体激振力对叶轮处振动特性及其轴心轨迹的影响。通过对不同位置的轴承处特性进行对比,研究轴承处的振动特征。结果表明：叶轮所受流体激振力具有多种频率成分,且激振力随工况的偏移逐渐增大,泵转子系统在不平衡质量力与瞬态流体激振力作用下,叶轮处的振动幅值最大,其次为轴承处。     

电磁动态密炼机四棱异步剪切型转子的设计及模拟分析

设计电磁动态密炼机四棱异步剪切型转子,建立在电磁振动条件下转子的三维数学模型,并运用专业流体软件Polyflow动态模拟分析转子流场的压力场、速度场、剪切速率分布、粘度分布、混合指数分布和浓度场。结果表明:在电磁振动条件下,转子流场出现最高压力、最大速度、最大剪切速率和最大质量浓度的时间缩短,转子突棱处的粘度很小,转子平滑处的粘度较大,混合指数较小,从而使胶料快速完成混炼,提高混炼效率,降低混炼能耗。     

自驱型旋转式压力能交换器的结构优化与动态性能研究

通过建立不同结构与动态操作参数下的自驱动压力交换器数值模型,分析了转子长度、端盖通道覆盖孔道个数及螺旋升角等结构参数对设备性能的影响规律,得到了不同操作参数下设备动态运行特性的变化规律,研究结果表明:转子长度为影响体积混合度的主要结构参数,增大转子长度可有效控制流体混合程度;随着进流速度增大,转子转速线性增大,流体混合加剧,压力交换效率显著减小;孔道与端盖存在动静干涉,使得高压出口处产生压力脉动,导致流体压力出现损耗,且随着进流速度增大,压力损耗增大,有效压力交换减小;而进流压力的影响较小。     

大功率汽轮发电机组超半频振动的测试和分析

本文通过对不同机组的低频振动进行现场测试,对产生低频振动的机理进行分析,提出了合理的部分进汽和转子较小的偏心以及良好的安装有利于降低超半频振动。消除振动的措施。     

轴承预负荷及叶轮质量对高速泵转子动力性能的影响

为抑制振动、优化提升高速泵转子动力性能,对高速泵轴承及转子系统建模,分析轴承预负荷及不锈钢、钛合金诱导轮叶轮状态下对转子动力性能的影响,计算结果表明预负荷的增加能够抑制工作转速下的振动幅值,转子的稳定性降低,但对数衰减率在0.1之上,满足稳定性要求;相比不锈钢诱导轮叶轮,钛合金诱导轮叶轮状态下能够大幅提高转子的临界转速。试验及现场应用表明:振动位移的峰峰值能够控制在合理范围内。预负荷可倾瓦轴承及钛合金诱导轮叶轮的应用优化了转子的动力性能,解决了实际工程问题。     

基于ARMD的轴承特性对转子临界转速的影响

通过改变轴承的油楔数、宽径比和间隙比,运用转子动力学软件ARMD,得到国产某型号双级透平发电装置中转子不同轴承特性下的临界转速。结果表明:采用4油楔轴承的转子一阶临界转速最大,且减小其轴承宽径比及间隙比有利于转子一阶临界转速的提高。     

一起轴流压缩机振动间歇波动故障分析与处理

在工况稳定的条件下,一台轴流压缩机间歇性地出现剧烈的振动波动。通过分析轴流压缩机振动波动前后的波形、频谱和轴心轨迹等特征,确诊转子发生明显的油膜涡动,且涡动频率与转子一阶固有频率接近是出现剧烈波动的主要原因。通过更换老化的静叶O形圈来消除静叶与转子间的摩擦以减小扰动力,并缩小进气侧轴承顶隙以提高轴承稳定性,轴流压缩机的振动间歇波动就可完全消除。     

催化剂结垢引起的烟气轮机转子振动特性分析

采用ANSYS软件对烟气轮机转子进行数值建模,对叶片表面结垢引起的烟气轮机转子振动特性进行分析。研究了模型在带有催化剂结垢情况下的振动特性,并探索了催化剂结垢质量变化的情况下,烟气轮机转子振动特性的变化规律;预测不同位置和质量的结垢对烟气轮机转子振动特性的影响规律。结果表明:烟气轮机叶片表面结垢的3个参数(偏心距、周向角度、质量)对转子振动特性的影响各不相同。结垢质量大小和偏心距严重影响烟气轮机转子振动速度,质量越大、偏心距越大振动速度越大,而结垢的周向角度对转子振动速度的大小没有影响。     

低温液化气体储存容器的绝热性能评价指标研究

采用液氮为低温储存介质,分别进行了试验和数值模拟。得到了低温绝热容器内部介质在不同充装率下的压力和蒸发率变化规律,建立了压升速率与蒸发率之间的关系。说明了压升速率作为低温液化气体储存容器绝热性能评价指标的可行性。     

负压空气橡胶隔振器静态特性研究

设计了一种基于负压空气和帘线-橡胶复合气囊的全新低频隔振器,建立了有限元分析模型,得出的静态力学特性与试验结果吻合较好,验证了有限元模型的正确性;同时,研究了不同负压腔室压力大小下的特性曲线。结果表明,负压空气橡胶隔振器具有良好的低频隔振特性。     

振动注塑对IPP/HDPE共混物力学性能和凝聚态结构的影响

研究了振动频率、振动压力对等规聚丙烯/高密度聚乙烯(IPP/HDPE)共混物力学性能和凝聚态结构的影响。结果表明,与未施加振动的静态试样相比,振动试样的力学性能得到提高。随着振动压力的提高,低频率振动试样的力学性能呈明显上升趋势;振动频率对低振动压力试样的力学性能影响较小。在试样的表层及次表层,聚合物晶体沿熔体流动方向均有明显的取向。而对于试样芯层,则只有在成型温度为190℃、振动频率为0.23 Hz、振动压力为90 MPa的条件下才能观察到明显的晶体取向。     

二氧化碳压缩机高压缸异常振动原因分析及处理措施

为了解决尿素系统二氧化碳压缩机高压缸2009年大修开车后轴承、出口管线振动异常的问题，结合机组的检修和运行情况，对振动异常的原因从检修维护的角度进行了分析，找出了问题所在，并采取了相应的处理措施，取得了良好的效果。     

主轴承供油联锁系统故障分析及对策

供油联锁系统对确保主轴的润滑起到了保障作用,主轴承供油联锁系统常见的有油泵电机及主电机之间的“硬联锁”和供油压力与主电机之间的“软联锁”,“软联锁”比“硬联锁”要来得安全,可靠,但也可能由于压力控制器,控制线路及主电机交流接触器等方面和故障,导致供油联锁系统失效。通过分析,总结故障原因,提出一些完善主轴承断油的防范措施,制定了一套行之有效的管理制度,并成为设备安全管理的重要内容,有效地保证了窑、磨等主轴设备的安全运转。     

压缩机低压缸非驱动侧径向轴承故障原因分析

介绍了合成气压缩机低压缸非驱动侧轴承温度缓慢上涨,最终造成轴承振动高这一故障现象,根据检修拆检情况分析了低压缸非驱动侧轴承故障原因,10月份检修后,低压缸非驱动侧轴承运行正常。     

新型旋转填料床强化气膜控制传质过程

转子结构为相互嵌套填料环的新型旋转填料床是基于强化气膜控制传质过程的新型高效传质设备,可适用于受气膜控制的吸收、精馏和低浓度工业气体的净化等过程。分别以化学吸收体系CO2-NaOH和物理吸收体系NH3-H2O测定了不同气量、液气比和超重力因子条件下的有效比表面积a和气相体积传质系数kya,并由此得到气相传质系数ky,对其传质性能进行研究。实验结果表明：a、kya和ky均随着气量、液气比和超重力因子的增大而增大。通过对比可知,新型旋转填料床的气相体积传质系数在相近操作条件下是文献逆流旋转填料床的2倍。并对实验数据进行了回归,拟合出了a、kya和ky分别与气相雷诺数ReG、液相韦伯数WeL和伽利略数Ga之间的关联式。     

Improving the mechanical properties of polypropylene via melt vibration

The effect of melt vibration on the mechanical properties of polypropylene prepared by low-frequency vibration-assisted injection molding (VAIM) has been investigated. With the application of melt vibration technology, the mechanical properties of polypropylene are improved. The yield strength increases with the increment of the vibration frequency, and a peak stands at a special frequency for VAIM; the elongation at break decreases first and then increases with increasing vibration frequency, and a valley stands at a special frequency. The tensile properties increase sharply at an enlarged vibration pressure amplitude with sharply decreased elongation at break. The Young's modulus and impact strength also increase with the vibration frequency and pressure vibration amplitude. When it is prepared at 59.4 MPa and 0.7 Hz, the maximal yield strength is approximately 40 MPa versus 33.7 MPa for a conventional sample; an 18.7% increase in the tensile strength is produced. Self-reinforcing and self-toughening polypropylene molded parts have been found to be prepared at a high vibration frequency or at a large pressure vibration amplitude. Scanning electron micrographs have shown that, in the vibration field, the enhancement of the mechanical properties is attributable to more pronounced spherulite orientation and increased crystallinity in comparison with conventional injection moldings. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Performance characteristics of a packing with boundary layer turbulizers Part 1. Pressure drop and loading point

A novel design of a honeycomb packing with turbulizers in the region of the boundary layer (Turbo-Pack) has been designed and investigated. The presence of turbulizers is shown to decrease the pressure drop per mass transfer unit in cases of both gas-film and liquid-film controlled mass transfer. A comparison of the best packings known so far from the literature shows that, regarding such an important parameter as pressure drop per mass transfer unit, the novel packing has significant advantages. On the basis of experimental data obtained by studying 11 different packing designs in liquids of various viscosity, equations for determining the performance characteristics of the novel packing are obtained. In the first part of this work, the data on packing design, pressure drop and loading point are presented.     

Vibratory Compacting of Metal and Ceramic Powders

This investigation was concerned primarily with the forming of alumina, chromium-alumina, and nickel-titanium carbide powders by low-frequency vibration. The effect of a wide variety of particle-size distributions on the forming properties of these compositions was studied. An instrumentation system was developed for measuring the vibratory forces employed. Results obtained with various low-frequency vibratory forming procedures are reported. Similar compositions were formed by dry pressing followed by hydrostatic repressing, and the properties of the specimens formed by the two methods are compared. The vibratory forming method offers a number of advantages over the hydrostatic method.     

Measurement and Analysis of Cavity Pressure and Melt Filling Capacity During Injection Molding

Using an online measure system consisted of a high sensitivity pressure sensor, a spiral channel mold and a data collecting/analysis series. The cavity pressure and flow length response under different injection pressure, injection velocity, mold temperature and different vibration condition was measured and analyzed in this study. The results show that the cavity pressure and flow length increased with the increase of injection pressure, injection velocity and mold temperature. In vibration assisted injection molding (VAIM), the cavity pressure and flow length increased as a result of imposing vibration. The change of amplitude and frequency in VAIM had more distinct effect on flow length than injection pressure. The results also indicate that the measure system established in this study can accurately monitor and record the changes of cavity pressure, and could be used in the study of melt's filling capacity in injection molding process.