内燃机整机振动模糊控制系统的设计

作者将模糊控制技术应用于内燃机整机振动动力减振器中，设计一种模糊控制系统，对减振器的刚度进行调节，使减振力能随内燃机振动的变化而变化，从而达到最优的减振效果。应用MATLAB进行仿真对比实验，结果表明这种控制系统是行之有效的。     

基于仿生设计学的内燃机活塞设计分析

对壳类拱形结构与活塞的受力特点进行了相似性分析,并对带加强筋的拱形结构进行了计算分析,在顶部小面积压力载荷作用下,带加强筋的拱形结构活塞不但有较好的承载能力,而且应力分布比较均匀,不会形成大的应力峰值,同时还可以改善热量的传递,降低温度,达到耐高负荷的目的,并且还可以减轻材料质量。     

基于仿生设计学的内燃机活塞设计分析

对壳类拱形结构与活塞的受力特点进行了相似性分析，并对带加强筋的拱形结构进行了计算分析，在顶部小面积压力载荷作用下，带加强筋的拱形结构活塞不但有较好的承载能力，而且应力分布比较均匀，不会形成大的应力峰值，同时还可以改善热量的传递，降低温度，达到耐高负荷的目的，并且还可以减轻材料质量。     

单缸发动机惯性力测试校正理论与实验的研究

单缸发动机中曲柄连杆机构的惯性力的大小与方向对车辆的振动和舒适性有相当大的影响,在中小排量的发动机中一般采用过量平衡调整一次惯性力的方法,但长期以来缺乏有效的实验研究手段。讨论了单缸曲柄连杆机构的理论惯性力曲线“力椭圆”和实验惯性力曲线“力8字”的关系,提出在摆架上逐点偏移气缸进行惯性力实验的方法,得到的实验惯性力曲线完全反映了惯性力的主要参数。在单缸发动机惯性力数学模型的基础上,研究了曲柄连杆机构的合成旋转质量的位置及与往复质量的比值这两个重要的设计参数与一次最大惯性力、主趋角、不平衡率的变化关系,讨论了单缸发动机惯性力参数选择依据。提出了惯性力参数的实验校正算法。     

碧口水电站~#1水轮机组增容改造后异常振动分析及处理

针对大唐公司碧口水电站#1机组增容技术改造后启动时的异常振动问题,通过采集上机架水平振动、主轴摆度等分析了引起#1机组异常振动的主要因素。分析结果表明,机组在不同运行状态下的综合稳定性特性是质量力、电磁力和水动力共同作用的结果,且在转子检修工艺中,应严格控制转子圆度,即使偏差在允许范围内,也要防止正偏差或负偏差集中到一侧。介绍了用动平衡方法解决碧口电站#1水轮机组异常振动问题的过程,提出了水电机组A级检修后的稳定性分析方法,同时提出了水轮机组技术改造和新机安装时的注意事项。     

华苑煤业10号煤层回采巷道围岩支护稳定性研究

为了解决因非对称力造成的巷道围岩大变形失稳,对原设计方案进行了改进,通过数值模拟的方法验证改进方案的可行性。结果表明,针对倾斜煤层,采用直墙半圆拱形巷道断面能够消除巷道顶板围岩中的应力集中现象,巷道顶板围岩破坏和下沉变形较原方案分别降低了42.85%和67.16%。     

V型双缸发动机惯性力测试及其调整方法研究

在分析V型双缸发动机惯性力数学模型的基础上,研究了理论惯性力曲线“力椭圆”和实验惯性力曲线“力八字”的关系,研究了曲柄连杆机构的合成旋转质量的位置及与往复质量的比值这两个重要的设计参数与一次最大惯性力、主趋角、不平衡率的变化关系,讨论了V型双缸发动机惯性力参数选择依据,提出了惯性力参数的实验校正算法。     

平面闸门启闭过程中的动水垂直力数值模拟研究

动水垂直力是影响闸门启闭力的重要因素,为准确计算闸门启闭力采用RNGk-ε方程紊流模型与物体移动模型(GMO)相结合的方法,对平面闸门启闭过程中的动水垂直力进行了数值模拟研究,以积石峡水电站泄洪洞闸门为例,分析了闸门不同底缘型式和不同启闭速率在闸门启闭过程中对动水垂直力的影响及动水垂直力在闸门启闭过程中的变化规律。     

Design of an integrated propulsion, guidance, and levitation system by magnetically excited transverse flux linear motor (TFM-LM)

A magnetically levitated vehicle dedicated for transportation systems requires propulsion, guidance, and levitation forces. The components used to generate these forces, such as linear motors and magnets, must have less mass especially because the magnetically levitated vehicle has to carry its own linear motor and magnet. In this paper, an integrated propulsion, guidance, and levitation system by magnetically excited transverse flux linear motor (TFM-LM) with high force and high efficiency is introduced. Analytical equations with one-dimensional magnetic equivalent circuit are developed to predict the propulsion force and to guide the design of TFM-LM. A three-dimensional (3-D) finite-element (FE) program calculates the propulsion force, the guidance force, and the levitation force of TFM-LM also, in order to verify the given specification. To verify the results of 3-D FE calculation, the computed propulsion force, guidance force, and levitation force are compared with the experimentally measured forces detected on the experimental setup. The calculated and measured performances of TFM-LM reveal a high potential of mass reduction for magnetic-levitated vehicles.     

测量活塞环切向弹力的新方法

在国际和国家有关活塞环的标准中,为消除摩擦力对活塞环弹力测量的影响,规定了先紧后松法和振动法,但均有缺点。基于摩擦力对活塞环和薄钢带受力的理论分析,得到了薄钢带拉紧活塞环至闭口间隙时的切向弹力Ftp和薄钢带放松活塞环至闭口间隙时的切向弹力Ftn与无摩擦力时的切向弹力Fto之间的表达式,建议了测量活塞环弹力的新方法;提出了求解摩擦系数,的非线性方程及其用割线法的求解方法;在摩擦系数,小于0．1的一般情况下,无需进行摩擦力影响的具体计算,可直接以(Ftp Ftn)／2作为Fto的实际值,这对正确而简单地改进活塞环弹力的测量有积极的意义。     

货车缓冲器关键参数对调车冲击影响的研究

在分析调车工况冲击过程的基础上,建立了详细的货车及车钩缓冲器参数化仿真模型;研究了货车缓冲器初压力、最大行程和最大阻抗力等参数对调车过程的影响;比较了刚性与柔性缓冲器对调车冲击的影响。研究结果表明：调车冲击时车钩力最大值随缓冲器预压力与最大行程的增大而减小,货车缓冲器最大行程取80—83mm为最佳;额定阻抗力的提高会增大缓冲器的回复力并产生更大的车钩力;性能优异的货车缓冲器必须具有刚性与柔性双重特性。     

Measurement method and results of ice adhesion force on the curved surface of a wind turbine blade

Experimental adhesion force measurements were conducted on accumulated ice on the leading edge of a scaled wind turbine blade in both glaze and rime icing regimes. An apparatus was first designed for specifically measuring the adhesion force of ice on a curved surface at climatic temperature where a vertical force was applied to the mounted structure in the test apparatus. Adhesion force measurements were measured and adhesion pressure calculated for plain and ice-mitigated test specimens. Results are presented for the increase in force of ice adhesion over a curved surface area in proportion to degree centigrade decrease in temperature.     

Gas diffusion layer deformation and its effect on the transport characteristics and performance of proton exchange membrane fuel cell

Cell/stack assembly force can strongly affect the transport characteristics and performance of a proton exchange membrane fuel cell (PEMFC) through causing the structural deformation. In this study, a mathematical model has been developed to investigate the effect of the assembly force for different gas diffusion layers (GDL) and membranes. The results indicate that the predominant deformation of the cell structure occurs in the porous GDL due to its weak mechanical strength. Thicker GDLs result into lower water content in the GDL structure, and can sustain a larger assembly force without the risk of “electrode flooding”; while thinner GDLs have higher water content, can maintain the hydration required for the membrane, and yield a better cell performance with less sensitivity to the variations in the assembly force. Thinner membranes yield better cell performance, but the cell performance is more sensitive to the changes in the assembly force. A combination of thin GDL and membrane is beneficial for better cell performance with reasonable sensitivity to the assembly force. For thinner GDLs, an optimal assembly force exists beyond which the cell performance is reduced; and practical cell assembly force will limit the GDL thickness.     

Force density limits in low-speed permanent-magnet machines due to saturation

This work discusses the practical limits imposed by magnetic saturation for the force density in low-speed permanent-magnet electric machines. The force density dependence on current density and slot depth is investigated with the aid of finite-element modeling. For saturation reasons, shallow slots are more favorable for achieving high force densities. However, for thermal reasons, deeper slots become favorable. Therefore, an optimum slot depth that maximizes the force density for each current density level exists. The maximum allowable slot depth range for four low-speed applications has been identified for a given maximum motor diameter.     

电磁力对导电流体二维流动的影响

导电流体在磁场中会受到电磁力的作用而导致流体运动发生改变。本文模拟了不可压缩粘性导电流体在不同外加条件下的流动状况。模拟结果表明：（1）电磁力与外加磁场和外加电场有关,对于不同的外加磁场和外加电场,导电流体所受到的电磁力作用也不同。对于外加垂直方向均匀磁场的导电流体在两电极间的流动,外加磁场和外加电场越大,电磁力越大;在外加电场和外加磁场相同的情况下,对于不同的进口流动速度,入口速度越大,导电流体的流动受电磁力影响越小。（2）在电极附近会产生端部效应影响导电流体的流动。     

风电叶片疲劳加载试验电磁激振特性研究

提出一种基于电磁力驱动的风电叶片疲劳加载新方法。为进一步得到电磁机构参数对激振力特性的影响规律,首先,以螺线管式电磁铁为加载装置,采用解析法构建电磁疲劳加载系统数学模型;其次,设计多阶段电磁激振力并通过能量守恒定律得到电磁力与叶片振幅和频率的关系;最后,利用ANSYS Maxwell软件建立磁场仿真模型,验证电磁激振力设计的合理性,并分析电磁铁结构参数对加载力及速度的影响,得出在给定的叶片规格下满足测试要求的电磁机构的线圈匝数、形状参数、铁心长度、铁心外径的优选范围,可为后续电磁式疲劳加载试验台的开发奠定理论基础。     

自动变速器用比例电磁阀电磁力计算及试验研究

介绍了自动变速器用比例电磁阀电磁力的2种计算方法即经验公式法和模拟计算法,通过Flux软件模拟分析电磁阀的电流、电磁阀行程和电磁力之间的关系,以及隔磁环的位置对电磁力的影响,并通过对隔磁环位置为4.5 mm的电磁阀试验,得到的电磁力验证了模拟计算的结果。     

体积力场对预混火焰面形状的影响

介绍了一种在燃烧场中产生大于1g体积力的实验系统,分析了影响体积力场的因素．利用实时摄像的方法,研究了在燃烧过程中体积力对预混火焰面形状的影响．结果表明,高温烟气在体积力场中的浮力效应,使火焰面向与体积力相反的方向弯曲、偏转．体积力增加将导致火焰面变形程度增加,并导致燃烧过程不稳定,以致发生熄火．气流的射流角不同,体积力对火焰面的影响效果不同,火焰面会发生弯曲、拉伸或压缩．当射流角为负值时,火焰容易发生吹熄．     

Magnetizing force modeled and numerically solved for natural convection of air in a cubic enclosure: effect of the direction of the magnetic field

Magnetizing force is modeled by considering magnetic susceptibility as a function of temperature and is included in a momentum balance equation as an external force term in addition to the buoyant force term. Under ideal gas behavior, the magnetizing force term can be represented by a new and simple non-dimensional parameter group γ, which represents the ratio of magnetizing force to the gravitational force. This magnetizing force acts on material of high magnetic susceptibility, like oxygen gas in a temperature gradient field, and affects the convection in addition to gravity. Sample computation was carried out for air in a cubic box that is heated from one vertical wall and cooled from the opposing wall, and has the other four walls thermally insulated. With an increase in the magnetic strength, the upward and downward natural convection in the gravity field becomes horizontal circulation under a cusp-shaped magnetic field.