操作状态下板式塔自振频率的影响因素

操作状态下的板式塔发生自振时,板上操作介质产生额外偏心惯性力矩,影响塔体的自振频率。通过对偏心惯性力矩的分析,得到了操作状态下板式塔自振频率的影响因素。对四个板式塔的计算表明,塔板直径大的板式塔应该考虑偏心惯性力矩。直径为2.4m的板式塔,塔板直径增加一倍,塔体一阶自振频率也相应增加一倍。板上介质液面高度增加,塔体自振频率增大。液面高度增加一倍,四个板式塔的一阶和八阶自振频率最大增加分别13.2%和16.2%。板上介质密度增加使塔体的各阶自振频率减小,长径比为13.5的板式塔,介质密度增加一倍,塔体自振频率减小50%。对结构相同的板式塔,操作介质密度对高阶自振频率的影响大于低阶自振频率。     

关于塔器许用挠度的探讨

本文对塔器许用挠度进行了探讨,说明控制塔器挠度的目的在于控制塔板上液层高度差,当某一块塔板处的塔体挠度使该塔板上液层高度层Δ′值等于该块塔板干板压降h_c的0.5倍时,该块塔板处的塔体挠度,即为该高度处的塔器许用挠度。     

自重对均布风载下等截面高塔塔顶挠度的影响

在对自支承式塔设备建立合理的力学模型并进行受力分析的基础上，采用材料力学中的叠加法，计算了高塔设备在均布风载荷、自重联合作用下的塔顶静挠度，提出对于自重和长细比均较大的高塔，塔体自重对塔顶挠度的影响不可忽视，并推导出了计算这种影响的表达式。     

一起罕见的高塔共振现象

一九八五年七月二日十三点五十分,兰州化学工业公司石油化工厂第二砂子炉车间正在被检修的丙烯—丙烷分离塔突然发生激烈的晃动。晃动时塔顶挠度达到1米左右,塔体弯曲如弓,大约每2秒钟晃动一个周期,晃动历时二个小时后逐渐减弱而停止。周围其它设备没有发现晃动现象。当时天空睛,有小风,无地震,基础无变化。这次晃动现象,塔顶挠度之大,时间之长,实为罕见。     

计算等截面高塔塔顶挠度的新方法

采用材料力学的叠加法和自编的MATLAB程序，计算了高塔设备在风载荷和自重联合作用下的塔顶静挠度，并推出了考虑自重影响时塔顶静挠度的计算公式。分析和计算的结果表明，对于自重和长径比均较大的高塔，必须考虑塔体自重对塔顶挠度的影响，且只要将高塔分三段以上进行类似的分析，就足以满足工程计算的精度要求。     

塔设备在内部流动载荷作用下的振动分析

塔设备的固有频率和相应振型由塔结构、材料特性、流动载荷以及约束等条件共同决定。当塔的振动频率与固有频率相同时将诱发共振,危害塔的正常工作。选取某石化企业的板式塔作为研究对象,在设计工况下分别采用传统理论的折算质量法与Workbench多物理场求解平台提供的流固耦合计算方法,对塔设备进行结构计算、模态分析和谐响应分析。其中流固耦合算法先对内部流场进行气液两相流稳态计算,然后对塔体进行静力结构计算,载荷条件有重力以及通过流固耦合界面施加到塔体的流动压力,计算得到了不同塔板数的塔结构位移、应力、固有频率及其振型等结果和规律。采用模态叠加法对板式塔进行了谐响应分析,得到了内部流动载荷对塔设备动响应的影响规律,为设备的安全运行提供技术支持。     

高耸塔器的风振模拟及其采用侧向支撑的减振分析

以某炼化工程中的高耸塔为研究对象,选取Davenport风速谱,基于M.Shinozuka谐波叠加法编制MATLAB程序,得到塔体脉动风载荷时程样本,对塔体进行顺风向的风振响应分析。结果表明,模拟的风载荷功率谱与目标谱吻合较好,且风载荷数据符合均值为零的正态分布,脉动风载荷模拟质量高;单独塔体在脉动风载荷作用1200 s,风振效应明显,塔顶最大位移可达到0.512 m;当塔体侧向支撑采用弹簧时,塔体晃动的减弱效果不明显;当塔体侧向支撑采用阻尼器时,塔顶最大位移随着阻尼系数的增加迅速减小,其值可减小到约0.1 m,塔体侧向设置阻尼器能够大幅防止塔体风振,有效提高塔体的抗风性能。     

焦炭塔塔壁温度场特性的研究（二）—周向温度场模型及其实测分析

根据焦炭塔的进料口结构和流体力学理论分析下介质进塔过程的流态,推断流态在塔内引起的周向不均匀温度场,理论分析表明：气密及预热时径向进料,热油和冷焦水经过塔底弯头进料是使介质产生偏流的主要因素;焦层孔道,塔壁硬垢以及弯头出口轴线与塔体中心轴线不一致对介质在塔内偏流起恶化作用,是次要因素,通过对实测结果的比较和分析,结果表明焦炭塔壁在整个操作过程中都存在周向不均匀温度场,并验证了关于进料流态的理论分析。     

风力发电机组塔筒的横向振动分析

结合有限元方法和工程计算对风力发电机组塔筒的横向振动进行分析.通过塔筒固有频率和风振频率的对比,判断塔筒容易发生共振的区域.给出并分析塔筒发生横向振动时塔顶最大位移、惯性力和特征弯矩的简化计算方法,并给出算例.计算了塔筒发生横向振动时的疲劳损伤.结果表明塔筒底部容易因横向振动而发生共振.     

摆塔式缆索式起重机塔架的技术特性

三峡摆塔式缆索式起重机塔架的下部支承选用径向轴承,可避免塔架纵向摆动时在塔架截面上产生弯矩；塔架底部设置了可阻止塔架扭动的防扭装置,塔架顶部采用可摆动的牵引索上支悬挂滑轮支架,可减少塔顶与塔架底部导向滑轮间的牵引索的斜拉,塔架标准塔节的结构便于制作及现场拼装。     

A new approach for bending analysis of thin circular plates with large deflection

This paper is concerned with bending analysis of an axisymmetric simply supported circular plate with large deflection. Based on the linear theory of thin plates, the incremental load technique is developed for solving the bending problem of a thin circular plate with large deflection. In the proposed method, the total applied load is divided into various small load steps. In each load step, the plate stress behavior is simplified to be linear. The incremental formulations are presented for the deflection and stresses of the plate when external loads increase. A numerical example is given to show simplicity and accuracy of the present method. It is found that the proposed method can be an alternative useful tool for engineering applications.     

面向绝对重力仪的光束垂直性快速调节

为了减小自由落体式光学干涉型绝对重力仪中光束垂直度对重力测量准确度的影响,提出了一种基于双层液体光楔对光束的可变偏折实现光束垂直性自校正的快速调节方法。当光束偏离铅锤方向时,利用液面天然水平的特性,使液体在重力的作用下形成可变液体光楔,自上而下的光束经双层液体光楔时光束传播方向发生偏转,合理地匹配双层液体的折射率,使它偏离铅锤方向的夹角得到实时修正。搭建光束垂直性自校正装置并进行实验验证,结果表明,装置的角度抑制比优于18.0,当装置倾斜角度不大于2.7′时,出射光束偏离铅锤方向不超过9.0″,对应于重力加速度的测量误差小于1 μGal (1 μGal=10^-8 m/s²)。将本方案用于自由落体式的重力加速度测量,仅通过条式水平仪调平便可实现光束垂直性的快速准确调节,同时还能抑制测量过程中光束垂直性缓变带来的影响。     

Strength calculation for forged straight bevel gear teeth having a linking web

When bevel gears are forged, a thin web results on the back of the teeth. This web, which results from the clearance between the dies, gives an additional strength not accounted for when the Lewis design criteria is used. To account for this extra strength a plate model is developed. The solution for this plate model can be obtained by assuming a polynomial deflection function. Using the Galerkin variational method the constants in this assumed deflection function can be calculated. The plate model is compared with a finite element model, using a general purpose program and also with experimental strain measurements. This proposed plate solution indicates an increase in strength of more than 25% in excess of that suggested by the cantilever beam model of Lewis when compared with the finite element results.     

Modelling of low velocity impact damage in Laminated Composites

In this study a simple model is developed that predicts impact damage in a composite laminate avoiding the need of the time-consuming dynamic finite element method (FEM). The analytical model uses a non-linear approximation method (Rayleigh-Ritz) and the large deflection plate theory to predict the number of failed plies and damage area in a quasi-isotropic composite circular plate (axisymmetric problem) due to a point impact load at its centre. It is assumed that the deformation due to a static transverse load is similar to that oc curred in a low velocity impact. It is found that the model, despite its simplicity, is in good agreement with FEM predictions and experimental data for the deflection of the composite plate and gives a good estimate of the number of failed plies due to fibre breakage. The predicted damage zone could be used with a fracture mechanics model developed by the second investigator and co-workers to calculate the compression after impact strength of such laminates. This approach could save significant running time when compared to FEM solutions.     

双缸体旋转斜盘式液压变压器特性分析

针对旋转配流盘式液压变压器在变压范围、流量脉动以及噪声控制上的不足,提出一种小流量脉动低噪音液压变压器方案。分析目前液压变压器的主要特点,基于一种旋转斜盘式双缸体液压变压器方案,通过增加柱塞数量并结合斜盘转角的初始位置控制,达到减小流量脉动和噪声的效果。分析斜盘转动的转角及其阻力矩变化规律,并进行变压比样机试验测试。结果表明,旋转斜盘式液压变压器宜将上止点与A口中点重合时作为斜盘初始位置,在斜盘转角小于100°时,新型液压变压器使得输出流量不均匀系数减小了约40%,随着转角的继续增大,输出流量不均匀系数趋于一致,试验结果表明新方案可实现较大范围的变压比。     

Nonlinear model-based control algorithm for a distillation column using software sensor

This paper presents the design of model-based globally linearizing control (GLC) structure for a distillation process within the differential geometric framework. The model of a nonideal binary distillation column, whose characteristics were highly nonlinear and strongly interactive, is used as a real process. The classical GLC law is comprised of a transformer (input-output linearizing state feedback), a nonlinear state observer, and an external PI controller. The tray temperature based short-cut observer (TTBSCO) has been used as a state estimator within the control structure, in which all tray temperatures were considered to be measured. Accordingly, the liquid phase composition of each tray was calculated online using the derived temperature-composition correlation. In the simulation experiment, the proposed GLC coupled with TTBSCO (GLC-TTBSCO) outperformed a conventional PI controller based on servo performances with and without measurement noise as well as on regulatory behaviors. In the subsequent part, the GLC law has been synthesized in conjunction with tray temperature based reduced-order observer (GLC-TTBROO) where the distillate and bottom compositions of the distillation process have been inferred from top and bottom product temperatures respectively, which were measured online. Finally, the comparative performance of the GLC-TTBSCO and the GLC-TTBROO has been addressed under parametric uncertainty and the GLC-TTBSCO algorithm provided slightly better performance than the GLC-TTBROO. The resulting control laws are rather general and can be easily adopted for other binary distillation columns.     

A dynamic model and numerical study on the liquid balancer used in an automatic washing machine

The rotational system of an automatic washing machine has two major technical difficulties. One is the collision of the tub against the frame at the beginning of its early spinning stage. A factor that causes such instability of the rotational object can be attributed to the deflection of the liquid inside the liquid balancer due to the unbalance mass. This study proposes the installation of a middle plate to avoid the deflection of the liquid and a CFD method is used to verify its effectiveness. The other is the whirling vibration occurred during the high speed rotation of the basket and it shakes the center of its rotational axis. This is because the balancer cannot generate enough restoration forces during its high speed rotation. It is necessary to employ the multi-race in the balancer in order to increase restoration forces. The analysis for the configuration has been performed using a dynamic model.     

下顶式压力机立柱的优化设计

以铜自动包装生产线致密工位中下顶式压力机为研究对象,运用ANSYS参数设计语言APDL进行建模,根据在偏斜载荷作用下立柱出现摆动的最大值,采用一阶法以压力机立柱半径为设计变量进行优化,从结果判断出符合使用范围的最优解,为该压力机的设计提供了理论依据。