DESIGN SENSITIVITY ANALYSIS OF ROTATING MACHINERY BY MODAL SYNTHESIS METHOD

A new method which is a combination of sensitivity analysis and modal synthesis technique was applied to the simple calculation of design sensitivities of the dynamic characteristics of substructurally combined rotating systems. In this paper the free interface mode method was introduced as a basic tool for the modal synthesis technique. As an example, the sensitivities of the critical speeds of a high-specd winding mechanism on textile machine with respect to design modifications were obtained by the new method introduced in this paper and compared with the values obtained by using another method.     

Kinematics and dynamics analysis of drive mechanism of parallel four-bar energy-saving pumping unit

The conventional beam pumping unit consumes a large amount of energy due to its unsmooth movement. In this work, we design a new energy-saving parallel four-bar pumping unit and derive the kinematic and dynamic law of the drive mechanism systematically by theoretical method. For the given target technical parameter, the theoretical results are verified by computer simulation, which shows that the simulation dynamic curves agree well with the theoretical ones and the calculated power consumption is low. Theoretical analysis shows that the newly designed pumping unit reduces average power by 28.8% compared with its conventional counterpart. The much lower theoretical energy consumption and the better dynamic performance indicate that the new energy-saving pumping unit is well designed and will have a significant application prospect.     

Design Criterion for Fixture Layout Based on the State Space Model in Multistation Assembly Processes

The fixture layout is crucial to assure the product quality in a multistation assembly process （MAP）. A well-designed fixture layout will make the final product＇s variability be insensitive to the fixture variation inputs. As the basis of the fixture layout design, the design criterion plays an important role in the effectiveness of a solution and the optimization efficiency. In this paper, an effective and efficient design criterion is proposed for the fixture layout with a fixed reference point （FRP） in an MAP. First of all, a state space model for the individual port＇s variation propagation and accumulation is developed, which is the mathematical foundation of the proposed criterion. Then, based on this model, a novel design criterion used to evaluate the performance of the fixture layout is proposed for the fixture layout with an FRP. Finally, a method extracted from the proposed design criterion is developed for quick fixture layout design. A four-station assembly process is used to validate the effectiveness and efficiency of the proposed models and methods.     

A New Sample-Selection and Modeling Method Based on Near-Infrared Spectroscopy and Its Industrial Application

Near-infrared （NIR） spectroscopy has been widely employed as a process analytical tool （PAT） in various fields; the most important reason for the use of this method is its ability to record spectra in real time to capture process properties. In quantitative online applications, the robustness of the established NIR model is often deteriorated by process condition variations, nonlinear of the properties or the high-dimensional of the NIR data set. To cope with such situation, a novel method based on principal component analysis （PCA） and artificial neural network （ANN） is proposed and a new sample-selection method is mentioned. The advantage of the presented approach is that it can select proper calibration samples and establish robust model effectively. The performance of the method was tested on a spectroscopic data set from a refinery process. Compared with traditional partial leastsquares （PLS） , principal component regression （PCR） and several other modeling methods, the proposed approach was found to achieve good accuracy in the prediction of gasoline properties. An application of the proposed method is also reported.     

Research on dynamic characteristics model test scheme for middle pylon of multi pylon multi span suspension bridges

Multi-pylon multi-span suspension bridge is a new type super flexible structure system, and the rigidity design of middle pylon is one of the main difficult technical issues. Due to the requirements of longitudinal rigidity, the structural form and the corresponding foundation type of middle pylon are different from those of the ordinary steel pylon, and the complicated dynamic characteristics make the calculation quite difficult. In this article, exploration has been made in selection of similarity ratio, selection of model materials, section simulation, restriction conditions simulation, fixing of mass blocks, fabrication scheme and testing method by taking into account different construction and working conditions such as restriction conditions and working environment of a 3-pylon suspension bridge, to conduct the test experimental design of the dynamic behavior of the middle pylon, with the purpose to reveal its dynamic characteristics and make comparison and analysis with theoretical assumptions, to provide basis for anti-wind and anti-seismic design and as a reference for the design and research of 3-pylon 2-span suspension bridges in the future.     

Theoretical analysis of a method for segmented heat exchanger design

In the process of the design of heat exchangers,it is difficult to establish the factors governing the optimal points of the design objective functions due to the contradictions and uncertainties of the design objectives.The variation of fluid properties is one of the main factors causing this type of uncertainty.Conventional design methods have not completely solved these problems.In the present work,based on the logarithmic mean temperature difference,a new heat exchanger design method(called the segmented design method) is proposed which takes into account the variation of fluid properties with respect to the temperature.In this method,the whole heat exchanger is first divided into several segments.Then by applying the principle of the conservation of energy and taking into account the initial conditions as well as the connecting conditions of the adjacent segments,the inlet and outlet temperatures of each segment are determined.Finally,the application of the logarithmic mean temperature difference method on each segment defines the heat transfer area.     

Study on conditions of internally carried air-launched launch vehicles based on the virtual prototype technology

A method based on the virtual prototype technology simulating the separation of a launch vehicle from its aircraft in the aircraft wake was proposed based on the internally carried air-launched launch vehicle program. In this method, the full-scale model of the aircraft, the vehicle and the parachute are constructed. Then, they are imported into the ADAMS software, constraint solutions and driving forces are then added for visual dynamic simulation. The unsteady aerodynamic forces of the vehicle in the aircraft wake are calculated by CFD and the moving grid technique. The forces generated by the parachute can be derived from the Kirchhoff motion equation. Through comparing and analyzing the simulation results under different launch conditions, it has been proven that this method simulates the separation of a launch vehicle from the aircraft in the aircraft wake accurately. It provides the foundation for the aggregate project of internally carried air-launch vehicles, and offers a new ref- erenced method for multi-body dynamic simulation.     

Investigation on wavelength switching of widely tunable SGDBR lasers

The sampled-grating distributed Bragg reflector （SGDBR） laser is a typical and important photonic integrated device, and has potential wide application to agile optical networks. A new dynamic model for this device has been developed, which combines the traveling-wave method for the active region and the transfer-matrix method for the passive sections into a single procedure. The behaviors of wavelength switching of the SGDBR laser, which include the transient spectrum and mode competition, have been studied in detail using this model. A new efficient way has been proposed to improve the wavelength switching performance only by increasing the coupling coefficients without changing the carrier density.     

Mechanical-Delay Dynamic Model of Magnetorheological Damper

In the dynamic characteristic experiment of magnetorheological（ MR） damper, a strange feature which the improved Bouc-Wen model based on tanh function cannot accurately describe has been shown when MR damper is reversing or at a low speed. In order to describe this phenomenon,a new mechanicaldelay dynamic model based on the improved Bouc-Wen model has been proposed for MR damper. This new model comprehensively considers the coupling effect on the structural flexibility of MR damper and the MR effect of MR fluid. The identification results show that the new mechanical-delay dynamic model for MR damper has a good coherence with experiment whenever at low or high speed.     

Optimization of Quality Consistency Problem of Electromechanical Component due to Manufacturing Uncertainties with a Novel Tolerance Design Method

The consistency problem caused by uncertainties in manufacturing process is a significant factor influencing the quality of electromechanical components. Currently, there are two approaches for reducing the influence of uncertainties. The first one is to improve the resistance capability of design scheme by using robust parameter design（ RPD） method with nonlinear feature of controllable factors. The second one is to control the influence of uncertainties by using robust tolerance design（ RTD） method with quality loss function,setting the optimal tolerance with the minimum total product loss as the objective. However, as for the electromechanical component, it is difficult to achieve nonlinear region owing to the restrictions of design parameters. In addition,the establishment of cost function in manufacturing process is also confronted by practical difficulties. In order to solve the quality consistency problem under the influence of manufacturing uncertainties,a novel tolerance design method was proposed for the electromechanical components. Through the experiment design and contribution rate analysis, key factors influencing the quality consistency were determined,and the tolerance allocation scheme was confirmed according to the consistency objective of quality.Then, quality distribution characteristics before and after the consistency optimization were analyzed and verified through the Monte Carlo stochastic simulation. The application result of electromagnetic relay proves the effectiveness of the method proposed in this paper.     

以CFD方法研究液压集成块设计策略

为使设计的液压集成块具有良好的通流品质,运用计算流体动力学(CFD)方法研究了其流道内部的流动特性.研究结果表明,孔道的布局及连通关系设计对块体性能优劣产生重要影响.在布局上具有相似性的孔道连通结构,应优先选择同面或邻面的布局方式;为提高孔道通流品质,根据工艺孔道结构与流道压降之间的关系,提出满足结构需求前提下缩短工艺孔道长度、增大孔径的优化设计方向,并通过计算低雷诺数局部阻力系数对直角转向的性能品质影响进行直角转向优化设计.从性能角度确立了集成块结构优化设计策略,为液压集成块性能约束与结构约束相结合进行全局性寻优设计奠定了基础.     

CFD辅助液压集成块管网优化设计

针对液压集成块(HMB)的结构优化设计问题,应用计算流体动力学方法(CFD),从提高块内管网液流的性能品质出发,建立了求解区域的几何网格及三维瞬态数值模拟的初边值条件.通过对管网典型流道结构数值模拟,定性地分析了液流在正交管路中的流态,得到了典型流道的结构形式对液阻性能的影响规律,进而提出流道在几何结构上的改进措施.HMB管网内流系统三维数值模拟结果表明,采用CFD方法研究HMB流道中典型结构的设计问题可以较准确地获得管网流场的基本结构特征,得到较为理想的管道布局结构,有效提高块体结构优化设计品质.     

滑动轴承动力特性的数值计算方法

将计算流体动力学与简谐激励法应用于滑动轴承动力特性系数的求解,通过采用全新的变流域动网格技术提出一种基于瞬态流场计算的滑动轴承动特性的计算方法。利用所提出的方法计算典型滑动轴承的刚度、阻尼系数,并与已有的经典计算结果进行比较。结果表明:两种方法的计算结果基本吻合,提出的新方法不仅考虑了计算初值的影响,而且计入了实际存在的油膜破裂现象,满足精度要求,有效可行。     

液压集成块装配过程仿真系统关键技术研究

为检验和比较液压集成块的设计结果,设计了液压集成块装配过程仿真系统.该系统在三维装配环境下,采用基于特征体素的参数化造型方法完成装配单元的实体模型表达;深入研究了装配路径的规划算法,根据液压集成块的特点,提出应用优化的启发式搜索算法A*进行装配路径规划;采用基于空间约束关系的坐标驱动技术实现液压集成块装配过程仿真;通过实例展示装配过程,验证了装配过程仿真系统的实用性和有效性.     

功率键合图法在血液循环系统计算机仿真中的应用

根据生物流体系同工程流体系统所具有的相似性，将功率键合图建模方法应用于人体血液循环系统的计算机仿真当中，对一个简化的人体血液循环系统模型进行了仿真研究，所得仿真数据同基本的生理规律符合较好，为生理医学仿真提供了一种易于理解和统一的建模方法。     

内燃机缸内气体CFD瞬态分析中动态网格划分技术

文中深入分析了在发动机CFD瞬态分析中的4类动态网格划分技术:弹性平滑方法、动态层方法、局部重划方法和ALE方法.在此基础上,研究分析了发动机CFD瞬态分析中动态网格划分技术的改进措施,提出了基于有限容积法的组合式动态网格技术更为适合发动机CFD瞬态分析中动态网格划分.最后,文中还以屋顶式双气门发动机为例进行了二维动态网格划分,并且运用基于有限容积法的组合式发动机动态网格技术方法实现了切向进气道发动机进气过程的三维瞬态数值模拟,得到了与实验观察相一致的结果.     

切向/螺旋进气道稳流实验与数值仿真

为了研究内燃机进气道及缸内的流动规律,并验证数值仿真在内燃机中流动的可行性,对典型的内燃机切向/螺旋组合进气系统的三维流场进行了稳流实验,并用商业软件Fluent数值仿真了实验条件下进气道及缸内流场.由文中给出的算法计算的涡流比及流量系数与实验结果具有较好的一致性.通过仿真流场分析发现,随着气流逐渐远离气缸盖,垂直于气缸轴向的截面上速度分布越规整,越易形成单一方向的旋涡.研究结果表明,数值仿真可以较准确地得到直观的进气道和缸内流场,补充了稳流实验.     

基于系统仿真和CFD的双系统冷凝器管路优化

将制冷系统仿真与计算流体动力学（CFD）模拟相结合,对一风冷双系统屋顶机的冷凝器进行管路布置的优化研究.CFD模拟空气的流动,得到冷凝器迎风面速度分布.通过制冷系统模型,对管路布置优化前后的冷凝器和制冷系统进行仿真计算.从部件和系统两个层面评价管路布置的改善效果.在部件层面,改进后的管路布置使冷凝器的换热量提高24.1%.在系统层面,单个系统运行时的制冷量增加3.6%,制冷系统性能系数（COP）提高8.1%.本研究思路对于相关产品的优化设计具有参考价值.     

独立B型液化天然气运输船绝热层#br# 局部失效对结构安全的影响

摘要： 根据独立B(SPB)型液化天然气(LNG)运输船绝热层失效后船体的传热特点,提出通过温度影响因子和面积影响因子分析船体结构温度场和内层对流空间空气温度场的耦合关系.选取液舱绝热层典型的局部失效模式,采用计算流体动力学(CFD)数值模拟和有限元分析求解失效前后船体温度场和温度应力,分析了绝热层局部失效对船体结构安全性的影响.对事故工况下SPB型LNG船的安全性评估具有一定的参考意义.     

基于CFD与最小二乘法的翼伞动力学建模

襟翼偏转气动计算是翼伞建模的关键问题,为提高翼伞动力学模型精度,本文引入襟翼偏转气动模型,提出CFD数值模拟与最小二乘辨识相结合的方法:数值模拟借助动网格动态捕捉翼伞外形与姿态变化,获取襟翼偏转气动数据;最小二乘法进行模型参数辨识,修正翼伞气动计算.研究表明襟翼偏转气动模型较好反映翼伞气动规律,对应动力学模型与空投试验数据接近,验证本文建模方法的有效性,为翼伞精确建模提供新思路.