带附加气室空气弹簧悬架动力学特性分析

基于气体热力学和气体动力学,推导了带附加气室空气弹簧垂向刚度表达式,建立了节流孔质量流率数学模型,并在AMESim平台下建立了带附加气室空气弹簧悬架的1/4仿真模型,分析了节流孔横截面积和附加气室容积对带附加气室空气弹簧悬架动力学特性的影响。研究结果表明：节流孔横截面积是影响带附加气室空气弹簧悬架阻尼特性的关键因素,随着节流孔横截面积的增大,带附加气室空气弹簧悬架阻尼特性呈现先增大后减小的趋势;增加附加气室可以减小带附加气室空气弹簧悬架系统刚度,增大附加气室容积可以降低带附加气室空气弹簧悬架系统的自振频率,有利于改善带附加气室空气弹簧悬架系统的隔振性能。     

动车组空气弹簧动态性能试验设计与研究

简要分析了一种带有附加气室的空气弹簧工作特点和动态性能计算方法,设计了一种新型用于自由振动试验的容积可调气室,并与受迫振动试验传统气室进行了分析与比对;通过在新型气室安装不同孔径节流阀,研究了不同容积气室和不同节流孔径对空气弹簧动态刚度、阻尼性能、共振频率和共振倍率的影响。结果表明,气室容积变小,空气弹簧动态刚度变大,阻尼性能、共振频率和共振倍率变化不明显;节流孔径变小,空气弹簧阻尼性能变大,动态刚度、共振频率和共振倍率变化不明显。     

空气弹簧有限元仿真方法的研究

介绍空气弹簧有限元仿真步骤,对螺钉紧固式和自密封式空气弹簧进行仿真模拟,并进行试验对比。利用螺钉紧固式空气弹簧仿真模型计算了胶囊的性能;利用自密封式空气弹簧仿真模型计算了整个空气弹簧(胶囊和辅助弹簧)的性能,包括胶囊气腔和附加气室在不同气体交换粘度下的空气弹簧载荷-气压关系、垂向刚度和横向刚度,据此提出空气弹簧的仿真模拟方案:先根据少量试验数据对比垂向刚度结果,优化出符合真实条件的空气弹簧系统的粘性特征,在此粘性条件下计算其他工况下空气弹簧的性能参数。     

双曲囊空气弹簧力学性能试验方案设计与检测

针对双曲囊式空气弹簧的力学性能试验,分析了膜式、囊式空气弹簧的结构及标准,设计了一种带附加气室并联组合试验方案。与单体式和无气室组合试验方案进行比对,研究了不同垂向预载对垂向刚度和横向刚度,不同振幅、频率对动刚度的影响。结果表明,垂向预载增加,双曲囊空气弹簧垂向刚度变大;横向刚度变小,垂向振幅增加,垂向动刚度变小,在0.5～1.5Hz区间频率增加对动刚度的影响不明显。     

曲囊式橡胶空气弹簧的一些力学问题

对曲囊式橡胶空气弹簧的承载面积、承载力、容积、内压和垂直刚度进行了力学分析，计算了胶囊经线方向断面圆弧的半个圆心角θ从８０°～１２０°范围变化时，橡胶空气弹簧各力学参数的数值     

胶囊容积计算宏应用于空气弹簧ANSYS多步分析

列举了空气弹簧ANSYS仿真过程中存在的一些问题和难点，针对空气弹簧分析过程中所存在的气压载荷问题，采取了多步分析的思路。在此思路的基础之上，提出了体积叠加法、离散求和法和拉格朗日插值函数法3种胶摩容积计算方法，并对每一种方法作了详细介绍。3种胶摩容积计算方法的提出，对于解决空气弹簧多步分析过程中的气压载荷问题有直接帮助，为胶囊容积计算宏的编写提供了思路和算法基础。最后将基于体积叠加法和离散求和法的胶囊容积计算宏应用于空气弹簧的垂向静态分析，得到了满意的结果。     

计量仪表的测量误差及防范措施

本文就计量仪表在测量中出现的误差,着重讨论了影响计量仪表误差较大的附加误差(流量系数、流束膨胀系数、节流件开孔直径、管道内径、被测流体密度和压差的误差等),同时提出了减小附加误差、提高测量精度的措施。     

石油模拟井流量调节阀流量特性与参数优化

针对流量调节阀流量特性差和压降特性不均匀的问题,利用数值模拟方法研究其节流口的流量特性与压差特性,发现节流口处流道面导致负压并引起压力非梯度变化是影响阀芯流通特性的重要因素.为此,以减小流阻提升流动特性为目标对节流口进行锐边优化设计.通过优化前后流动特性对比,说明倒角、圆角化等制造工艺可以大幅减少流体截面突变,有效提升...     

APDL实现空气弹簧动态试验仿真

介绍了EQ6111空气弹簧的试验方法和结构材料特点，并针对性地在ANSYS中建立了空气弹簧的三维有限元模型。针对空气弹簧分析过程中所存在的气压载荷问题，采取多步分析的思路，基于离散求和法APDL编写胶囊容积计算宏，应用于空气弹簧的垂向和横向动态力学性能分析，得出了位移载荷频率分别为0．5Hz，1Hz，2Hz和2．5Hz下的横向和垂向动态力学性能分析结果。研究表明，载荷频率是影响空气弹簧动态力学性能的关键外在因素之一。本文的研究为更进一步的空气弹簧动态力学性能的有限元分析奠定了基础。     

浮选柱结构参数对锶的浮选率影响的研究

研究了浮选柱浮选法对锶的浮选。考察了在锶最优浮选条件下浮选柱的高度、直径、布气室、微孔发泡器型号及柱形变化对浮选柱浮选法的影响。通过实验可知,浮选柱直径、发泡器、布气室、球型浮选柱都对锶的浮选率都有很大的影响;而浮选柱高度对浮选率的影响不大,但是在相同条件下,合适浮选柱高度可以缩短浮选时间;当选择合适的尺寸和球形柱,锶的浮选率最高可以达到97%。     

激光成像技术在气泡生成行为研究中的应用

针对液相中单喷嘴的气泡生成过程,采用激光成像技术结合电荷耦合器件(Charge Coupling Device, CCD)摄像机照相方法研究了甘油水溶液中的气泡生成行为,结果表明该法能够获得清晰的二维气泡放大图像. 考察了溶液浓度、气室体积、喷嘴直径和气体流量对气泡分离体积的影响,发现气泡分离体积分别随着溶液浓度和气室体积的增大而增大;在所研究的喷嘴直径(1, 1.5和2 mm)范围内,气泡分离体积随着喷嘴直径的增大而减小;气体流量对气泡分离体积的影响与喷嘴直径有关,当喷嘴直径为1和1.5 mm时,气泡分离体积随着气体流量的升高而增大,但当喷嘴直径为2 mm时,气泡分离体积随着气体流量的升高先减小后增大.     

BUBBLE FORMATION FROM AN ORIFICE SUBMERGED IN LIQUIDS

The phenomena of the bubble formation from an orifice submerged in a liquid is classified according to their formation mechanisms and the estimation expressions of the bubble volume are reviewed

The revised two-stage model of bubble formation accompanied by the pressure fluctuation in the gas chamber is presented and the results computed by this model are compared with the experimental results obtained for relatively wider range of gas chamber volume. Effects of some factors on the bubble volume, such as, gas chamber volume, orifice diameter, physical properties of gas and velocity of surrounding liquid are discussed     

流延设备负压真空箱流场仿真研究

采用Fluent软件对流延设备负压真空箱内部流场进行数值模拟研究,得到了真空箱内部的速度场和压力场,分析了压力损失过大的原因。提出了用单层均风孔板替代原双层均风孔板的优化方案,并分析了单层均风孔板位置、孔径和形状对真空箱性能的影响。分析结果表明,单层均风孔板位置、孔径和形状对真空箱进出口总压降影响不大,对真空箱均流效果影响显著。均风孔板距离真空箱背板150 mm,圆孔直径为6.8 mm时,真空箱综合性能最佳,优化后进出口总压降减少了10.1%。     

Effervescent atomization under sub-sonic and choked conditions—a theoretical approach

Spray formation of a bi-component mixture under sub- and choked-flow conditions has been studied. Special attention has been drawn to the processes inside the atomizer, i.e., the expansion chamber and two orifices. The relevant processes, which include the pressure drop at the inlet orifice, nuclei formation, bubble growth inside the expansion chamber, pressure drop at the discharge orifice, the velocity slip between the bubbles and the liquid bulk, and the flow regime (sub- and choked-flow) at the discharge orifice, have been analyzed by using a one-dimensional model approach.Three different operating regions have been identified. In the 1st, when the inlet to discharge orifices' diameter ratio is small, subsonic flow is anticipated, and no noticeable slip between the bubbles and the bulk liquid is expected. As the orifices' diameter ratio increases, the slip becomes more and more significant (2nd region). When the pressure at the expansion chamber exceeds the critical pressure, the flow chokes, and the slip maximizes. Further increase results in maximum slip (3rd region).The two main roles of the expansion chamber were described: (a) to provide the required time for the bubbles to grow till one bubble touches the other, and (b) to provide the discharge orifice with a well-mixed mixture to allow dominant flashing enhanced by shear stress disintegration. Optimized operation conditions for best atomization, optimized expansion chamber volume, and optimized orifices' diameter ratio are proposed in terms of the thermodynamic properties of the mixture.     

Equilibrium shapes and quasi-static formation of bubbles at submerged orifice

A detailed analysis of the effect of chamber volume, orifice radius, orifice submergence and contact angle on quasi-static formation of bubbles is presented. It is shown, that many aspects of slow bubble formation, involving phenomena leading to various modes of the bubble release, as well as the maximum orifice diameter which sustains a bubble at equilibrium, can be explained on the basis of information on equilibrium shapes and conditions. Scaling rules enabling adoption of results for water to other liquids are also presented.     

Multistep analysis of the mechanical performance of an air spring

New methods for testing air springs have received a lot of interest in recent years. In this article APDL (ANSYS parametric design language) was utilized to simulate static and dynamic test process of air springs. In the simulation, multiple load steps solution was carried out through APDL *DO‐LOOP and array parameter method. The program (capsule volume calculating macro) based on scatter sum method enabled the loop. The scalar quantity PRESSURE was established as inner tracking parameter to update inner pressure. Table parameter PRESSURES was established as inner pressure output parameter to export inner pressure of each load step. According to rubber elastic behavior and cord‐rubber composite aeolotropy, hyper elastic element and layer element were preferred for simulation. Comparison was done between static simulation results and corresponding test data to prove feasibility of multistep analysis. In consequence, some major parameters such as cord angle, initial inner pressure, and auxiliary chamber volume were taken into account, which have remarkable effect on static mechanical performance of EQ6111 air spring. Finally, the same method was applied to the simulation of dynamic test process, achieving abundant analysis results according to every 0.5 Hz increment of load frequencies varying from 0.5 to 2.5 Hz. Load frequency threw remarkable effect on the dynamic mechanical performance of EQ6111 air spring, because inertial effect and damping effect played important roles therein. The study aims to make contribution to the development of platform of air spring simulation and parameterized design (PASSPD). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(ethylene terephthalate) nanofibers prepared by CO2 laser supersonic drawing

Poly(ethylene terephthalate) (PET) nanofibers were prepared by irradiating a PET fiber with radiation from a carbon dioxide (CO₂) laser while drawing it at supersonic velocities. A supersonic jet was generated by blowing air into a vacuum chamber through the fiber injection orifice. The flow velocity from the orifice was estimated by computer simulation; the fastest flow velocity was calculated to be 401 m s⁻¹ at a chamber pressure of 6 kPa. A nanofiber obtained using a laser power of 8 W and a chamber pressure of 6 kPa had an average diameter of 193 nm and a draw ratio of about 900,000. This technique is a novel method for producing nanofibers.     

水平管内多孔板后的气液两相流型可视化实验

多孔板后是否形成均匀分散的泡状流流型是影响多孔板废气吸收装置吸收效果的关键因素。以空气和水作为两相介质,对气液两相混合物在水平管内流经多孔板后形成的流型进行实验。通过孔径分别为2、3、4、5 mm的4只多孔板在内径98.5 mm水平有机玻璃管内的可视化流动及高速摄像,研究了孔径大小、气相流量变化及液相流量变化对多孔板后流型的影响规律。实验结果表明：水平管内插入多孔板后,分层/塞状流转变边界向液相流量增大方向推移,塞状/泡状流转变边界向液相流量减小方向推移;随气相流量减小或液相流量增大,多孔板后流型趋于形成泡状流;孔径大小对多孔板后流型具有重要影响,减小孔径使塞状/泡状流转变边界移向更大气相流量和更小液相流量,即形成泡状流的两相流量范围增大;随孔径减小,孔板后流型趋于由分层流直接过渡至泡状流,塞状流趋于消失。为保证多孔板吸收装置的良好流型和吸收效果,建议多孔板孔径不大于3 mm。     

A New Electrospray Aerosol Generator with High Particle Transmission Efficiency

A new single-capillary electrospray (ES) aerosol generator has been developed for monodisperse particle production with maximal transmission efficiency. The new generator consists of both a spray chamber in a point-to-orifice-plate configuration and a charge reduction chamber that can hold up to 4 Nuclespot ionizers (Model P-2042, NRD Inc.). The 2 chambers are partitioned by an orifice plate. To optimize the particle transmission efficiency of the prototype, a systematic study was performed on the generator by varying the system setup and operation. Two key dimensions of the generator setup, the orifice diameter and the distance from the capillary tip to the orifice plate, were varied. Fluorescence analysis was applied to characterize the loss of ES-generated particles at different locations of the prototype. It was found that particle loss in the generator could be reduced by either increasing the orifice diameter or decreasing the distance between the capillary tip and the orifice plate. Increasing either the total radioactivity of the ionizers or the flowrate of the particle carrier gas also further decreased the particle loss in the system. The maximum particle transmission efficiency of 88.0% was obtained with the spray chamber fully opened to the charge reduction chamber, the capillary tip at the same level as the orifice plate, and 4 bipolar ionizers installed.