异型排列管束蒸发器壳程流场数值模拟

制冷装置蒸发器应用广泛,其壳程内流体的流体力学行为对蒸发器蒸发性能影响显著.利用Gambit软件建立了5种管束排列方式下蒸发器壳程流体流动的二维模型,采用Fluent软件对流体在壳程通道内的流动进行数值模拟.模拟结果表明,相比管束正方形排列和转角正三角形排列,异型排列方式更有利于壳程流体与管换热面接触,流体绕流异型排列管束的压力损失小于正三角形排列.研究结果为蒸发器设计及生能优化提供参考依据.     

往复压缩机吸气阀通道内流场数值模拟研究

往复压缩机的效率首先取决于气阀,气体的非稳态流动是引起阀片的非正常运动(颤振、关闭延时)原因,也是气体流动损失的主要原因。利用标准k-ε模型对吸气阀口形状及进出口通流面积之比进行了流场数值模拟,结果表明,随着吸气阀口的倾斜角度增大,气阀通道出口两侧的涡旋区域越大,造成流体的压力损失也就越大,另外还研究发现吸气阀的进出口通流面积之比值越小,流体的压力损失越小。最后通过试验验证了仿真的正确性。     

水润滑轴承水膜压力损失机理研究

针对已有水膜压力无线传感测试方法中由于设置L型管道从而导致传递过程中水膜压力的损失问题,采用数值分析法建立了水润滑轴承系统管道压力损失数学模型,用ANSYS软件建立了物理模型,通过仿真分析了压力损失机理,并对试验结果进行了校正与分析。结果表明:管道入口处润滑水的流量越高,水膜压力损失越大;轴转速越高,局部压力损失越大;管道越长,L型管道直管段压力损失越大,在动态工况下管道的压力损失与能耗比静态工况下的大。     

内置扰流柱的人字形板式换热器的数值模拟

设计了一系列具有不同尺寸扰流柱的人字形板式换热器,基于COMSOL软件研究其传热效率.应用了冷热双通道模型,并创新性的提出了在人字形纹波中间添加空心的扰流柱.通过数值模拟方法研究了冷热双通道模型中的多物理场(流体流动和温度).仿真结果表明,扰流柱可以减小通道两侧速度较小的流动区域,从而使温度传递更加均匀.此外,内置扰流柱的通道出口处的压力损失很小.为了进一步降低压力损失,可以在出口处不设置扰流柱.同时,与传统板片相比,内置扰流柱板片可将传热效率提高3％.     

动力电池冷却系统流量分配特性研究

利用CATIA软件建立动力电池冷却系统的内部流体域几何模型,通过STAR CCM+软件对乙二醇冷却液的流动情况进行模拟,得出流场的流量分配情况及其压力损失值。理论分析冷却液的流动机理,并结合数值模拟结果对冷却系统流体域的几何结构模型进行优化改进。由于流场的流体分配主要受阻力作用和分流、汇流作用的影响,通过重置管路布置的方式来调节分流、汇流作用,改变进出口五通接头及排出(吸入)Y型三通接头等连接件的结构参数来调整各流道流动阻力,使系统内进行换热的各冷却液流道流量分配达到均匀。系统优化后的流量分配情况良好,各流道内流体的速度趋于一致,故各流道汇流时所产生的湍流混合冲击损失减少,降低了流体阻力损失。     

铰链机构磨损的数值仿真

以数值仿真技术对曲柄滑块机构中的铰链摩擦副磨损状态进行了研究；考虑到压力和温度的影响，建立了铰链机构的磨损仿真模型；对机构中三对铰链接触处的磨损提出了具体的算法方案，在Visual Basic环境下编写了通用程序，获得了更加准确的仿真结果。     

结构参数对抛物线型柔性铰链刚度的影响

刚度是衡量柔性铰链机械特性的重要指标,运用材料力学和微积分等理论,建立了抛物线型柔性铰链的弯曲刚度和拉伸刚度模型,获得了不同尺寸参数对应的解析解;分析了抛物线型柔性铰链刚度对结构参数的依赖程度,发现了其具有明显的尺寸效应;建立了抛物线型柔性铰链有限元模型并进行数值模拟,理论模型解析解与数值模拟结果的相对误差小于8.5%。研究结果为进一步优化设计铰链结构参数提供了重要依据。     

考虑最小尺寸控制的压力驱动柔顺机构拓扑优化设计

拓扑优化设计的压力驱动柔顺机构拓扑构型容易出现类铰链结构,导致难以制造加工。为了满足制造工艺要求,提出一种考虑最小尺寸控制的压力驱动柔顺机构拓扑优化设计方法。采用改进的固体各向同性材料惩罚模型,利用达西定律结合排水项计算流体压力载荷,以机构的互应变能最大化和应变能最小化为优化目标,采用Otsu算法和拓扑细化算法提取柔顺机构的骨架特征,从而构建最小特征尺寸控制,以结构体积和最小特征尺寸作为约束,建立考虑最小尺寸控制的压力驱动柔顺机构拓扑优化模型,采用移动渐近线算法进行压力驱动柔顺机构拓扑优化问题求解。数值算例结果表明,所提设计方法获得的压力驱动柔顺机构最小特征尺寸满足约束,能够有效地抑制类铰链结构,并且分析不同最小控制尺寸对柔顺机构拓扑优化结果影响规律。     

基于数值仿真技术求解铰链机构磨损概率寿命

以数值仿真技术对曲柄滑块机构中的铰链摩擦副磨损状态进行了研究,建立了同时考虑压力和温度影响时铰链机构的磨损仿真模型,对3对铰链接触处的磨损提出了具体的算法方案,在Visual Basic环境下编写了通用程序获得了更加准确的仿真结果。首次提出了磨损概率寿命的概念,在载荷呈正态随机分布时利用蒙特卡洛法计算出3对铰链摩擦副的磨损概率寿命。     

调压阀流体空化特性仿真及影响因素分析

针对船用二级调压阀空化问题,建立流域瞬态仿真模型,结合Singhal空化模型和标准k-ε湍流模型对调压阀流体空化现象进行数值模拟,通过流场气体体积分数分析,得出了流体空化强度及分布形态的演变规律,通过流体速度场和压力场分析,阐明了空化演变过程调压阀流场特性,进而研究了开度、流量和背压对调压阀流体空化现象的影响规律.结果...     

水铰链综合试验装置研制

为研究机械密封式水铰链在带载运转情况下的密封性能,指导水铰链的研制和开发,文中在以往试验装置的基础上,研制了水铰链综合试验装置。介绍了该装置的原理、整体结构及运行情况。该装置由温度调节系统、压力流量调节系统、伺服驱动系统及数据采集处理系统组成。该装置温度可控,转速可调,测试界面友好,测试数据直观可视,能进行水铰链在不同压力及流量下的运转试验。该装置为水铰链产品的研制及性能评价提供了有效的试验手段。     

回转接头耐久性试验液压加载方法及系统

为了测试回转接头的内泄漏、外泄漏、及回转接头各零件的强度,根据回转接头的加载要求,确定了回转接头的液压加载方法,采用了压降法测量回转接头的微小内泄漏,并推导了内泄漏量计算公式,提高了测量准确度、缩短了试验时间。构建了回转接头液压加载系统,采用高压发生器使回转接头高压通道压力长时间稳定在42 MPa,同时系统可以对回转接头高压通道、低压通道进行循环冷却,避免了回转接头温升过高,驱动电机卡死。系统满足耐久性试验对回转接头加载的要求,为国内回转接头耐久性试验方法及设备研究提供了参考。     

结构参数对液压旋转接头密封性能的影响

为探究结构参数对液压旋转接头间隙密封性能的影响规律,分别以泄漏量和压力损失作为液压旋转接头的性能指标,研究密封有效长度、密封直径、密封间隙值3种主要结构参数对旋转接头性能的影响。采用正交试验与Fluent流体仿真相结合的方法,分析液压旋转接头间隙密封在不同结构参数下的泄漏量和压力损失情况。结果表明：3种结构参数对泄漏的影响程度由大到小依次为密封间隙值、密封有效长度、密封直径,对压力损失的影响程度由大到小依次为密封有效长度、密封直径、密封间隙值;密封间隙值大小对泄漏量影响非常显著,泄漏量随着间隙的增大呈指数增长关系,而间隙密封有效长度、环形密封直径对泄漏量无显著影响;密封有效长度对压力损失有极其显著影响,而密封直径和密封间隙值对压力损失没有显著影响;从整体上看密封间隙值、间隙密封直径、密封有效长度都大致与压力损失呈一次函数关系,且前两者与压力损失呈正相关关系,后者则与压力损失呈负相关关系。     

Design method for flow tube structure of electromagnetic water meter with shrunk measurement tube based on pressure loss-flow restriction

Due to the low flow rate measurement demand for battery-powered electromagnetic water meter, shrunk measurement tubes (such as circular section transition to square section) are often used to enhance flow velocity and measurement performance at small flow rate. However, this will also result in an increase in sensor pressure loss, even exceeding the pressure loss limit. Therefore, it is necessary to study a flow tube structure design method based on pressure loss-flow restriction, and design a flow tube structure which can not only maximize the induced voltage, but also meet the actual pressure loss requirement. Because there are many unknown variables in the formula of pressure loss mechanism, it cannot be directly used in structural design. Therefore, taking DN100 sensor as an example, based on finite element software, the variation of pressure loss with the length, width and height of rectangular section is obtained by orthogonal test method, and the numerical model of pressure loss is established. According to the requirements of industry and induced voltage enhancement, the optimal rectangular section size is found with the established pressure loss numerical model, and the structure of flow tube transition section is further optimized to reduce pressure loss. Finally, the prototype is made according to the optimized structure. Pressure loss experiment shows that the error between simulated value and measured value is within ±2.68% (±0.4 KPa). It means the pressure loss-flow restriction based design method for flow tube structure of electromagnetic water meter with shrunk measurement tube is effective and reliable.     

Formation of transfer layer and its effect on friction and wear of carbon–graphite face seal under dry,water and steam environments

The present work aims to explore the friction and wear characteristics of antimony-impregnated-carbon–graphite material used in steam rotary joint and to study the transfer of graphite films from seals to mating metal surfaces. An experimental facility consisting of a 1.3 MPa capacity boiler to supply saturated steam, a torque sensor, a displacement sensor, two thermocouples, a data acquisition system, a bakelite coupling to insulate the torque sensor, a 2237 W (3 hp) A.C. motor with frequency drive to control the rotational speed of shafts, and actual rotary joint has been developed to measure the instant friction losses and calculate the wear loss of four seals used in rotary joint. Wear loss, friction torque and surface temperature of sealing surfaces have been measured under dry, water and steam lubrication conditions. The obtained results are tabulated and plotted for quick understanding of experimental findings. Discussions on the excessive wear rate due to the presence of abundant water, misalignment and closing force are presented. Finally design changes to enhance the seal life are recommended.     

一种新型棱镜型双通道光纤旋转连接器的设计

目的：光纤通信技术提高了信息传输的速率和容量,目前它已成为一种主要的信息传输技术。在某些信号旋转传输的特定场合中需要使用以光信号传输为基础的光纤旋转连接技术。光纤旋转连接器因其具有传输容量大、体积小、重量轻以及良好的电磁兼容特性等优点而被广泛研究和应用。方法：本文分析了棱镜型多通道光纤旋转连接器的结构及原理,对解旋转机制进行了分析,并由此设计了一种新型的方双柱面解旋转棱镜结构的双通道光纤旋转连接器。结果：通过对该结构的光纤旋转连接器的耦合特性分析,结果表明其损耗主要由机械误差和解旋转棱镜球差所产生,数值模拟结果表明该结构的光纤旋转连接器的插入损耗可低于2.0dB。结论：这一性能完全能满足雷达等相关军事装备对其应用的要求,具有广泛的应用前景。     

旋转式唇型圈停车密封开启全过程密封特性研究

为探究旋转式密封圈脱开全过程的密封性能参数变化,借助非线性有限元软件ANSYS,建立三维的"超弹性体"的两参数Mooney-Rivlin橡胶模型、弹簧和"刚体"的静止轴模型,研究传统唇型密封圈和2种新型唇形密封圈(G形与S形)在脱开过程中接触压力、接触宽度、摩擦力的变化规律,分析入口压力、过盈量、弹簧力、橡胶密度对脱开...     

偏心负载作用下摆动气缸速度稳定性的研究

本文针对偏心负载作用下的摆动气缸速度稳定性问题进行了研究.讨论了偏心负载下摆动气缸运动过程中不稳定现象的成因、特点和规律,并提出了一种偏心负载下摆动气缸速度稳定性优劣的评价指标αc,数值仿真和实验验证证明了该评价指标的有效性和合理性.研究结果为进一步解决偏心负载作用下摆动气缸速度稳定性问题提供了理论依据和衡量标准.     

Numerical and experimental investigation of the metering characteristic and pressure losses of the rotary tubular spool valve

This paper presents the results of numerical and experimental performance evaluation of the rotary tubular spool valve. The aim of this work is to develop further the novel design of the tubular spool valve by confirming experimentally the validity of the simulation model and its results, thereby proving the valve's potential to represent a feasible and more efficient alternative to conventionally used translation spool valves avoiding the use of two stage valve configurations. In this research the valve performance is assessed through numerical modelling and experimental studies of its metering characteristic and pressure losses. This paper demonstrates that the used valve model yields the results, which agree well with the conducted experimental study. Therefore, validation of the numerical model and the modelling results in the form of theoretical valve characteristics was accomplished. Firstly, the paper presents details of a numerical approach employed to evaluate valve performance and then analyzes the simulation results. Next, the valve performance is experimentally validated by testing a prototype valve on a hydraulic test rig capable of measuring the volume flow rate, pressure levels in up- and downstream lines of the valve across the entire spool angular stroke. Initially, average discrepancies between modelling and test results were 52.46% for the metering and 82.78% for the pressure loss characteristics. Correcting the model geometry aimed at eliminating differences between the valve model and the practically used prototype-test rig system enabled reduction of the error between experiment and modelling by 47.75% for the pressure loss function. This confirmed validity of the simulated characteristics of the valve. The benchmark comparison of pressure losses confirmed average 71.66% energy dissipation reduction compared to the industry-available analogue valve.     

机械动密封水铰链设计及其有限元分析

文中针对某机械动密封、自动补偿水铰链的技术指标要求,结合该水铰链的组成原理、密封形式、关键技术,计算得出有关参数.运用Pro/E软件建立其三维模型,并导入ANSYS软件进行有限元仿真分析,仿真结果为该水铰链的结构设计及优化设计提供了参考依据.