汽车离合器用磁流变液不同转速下传递转矩的分析

介绍了磁流变液离合器的工作原理,并通过实验对汽车磁流变液离合器系统中磁流变液在不同转速工况下的传递转矩工作性能进行了分析。     

汽车用磁流变液离合器中的磁流变液性能分析

介绍了磁流变液这种智能材料的组成、特性及流变机理,并通过实验对汽车磁流变液离合器系统中磁流变液磁扭转力与电流及其自身磁粉固含量之间的曲线关系进行了分析.     

扭曲椭圆管换热的壳程强化传热特性

通过搭建扭曲椭圆管换热器壳程传热与压降性能测试平台,对扭曲椭圆管换热器壳程传热与压降性能进行了实验测试,以实验数据为基础对前人得到的壳程传热与压降性能计算准则关系式的应用范围进行了分析,同时拟合得到了测试用扭曲椭圆管换热器壳程传热与压降性能计算准则关系式,设计了与测试扭曲椭圆管换热器结构类似的折流板换热器以及折流杆换热器,采用相关计算方法对换热器的传热与压降性能进行了计算和比较,并分析了3台换热器的综合性能,结果显示扭曲椭圆管换热器传热效果好、压降低,具有很好的工业应用前景。     

风洞真空排气系统直接接触传热过程

某风洞真空排气系统在运行过程中,会产生大量含水蒸气的混合气体。为了提高排气效率降低能耗,本文引入冷凝塔工艺,采用直接接触换热冷凝方式使来流含水蒸气的混合气体降温冷凝。基于微元塔高传质模型,对进入冷凝塔的热流气体与冷却水直接接触换热过程分析,推导出传质系数数学方程表达式。结合实验数据考察了进气压力与冷凝降温排出气体中水蒸气含量的影响,并拟合得到一定温度下进气压力与该气体水蒸气含量的数学表达式;也考察了冷却水质量通量和气液比变化对传质系数、体积传热系数、出气温度的影响,在此基础上拟合得到针对风洞气流直接接触换热气液比与体积传热系数数学关系式,并计算出最优气液比。实验得出的规律对风洞气流的直接接触换热优化设计和应用起到了指导作用。     

三面加热窄矩形通道内饱和沸腾起始点的实验研究

以去离子水为实验介质,对截面为3 mm×43 mm的三面加热窄矩形通道内饱和沸腾（FDB）起始点进行了实验研究。分析了部分热工参数对饱和沸腾起始点的影响,对三面加热窄矩形通道内饱和沸腾起始点的数据进行非线性回归分析,得到适用于三面加热窄矩形通道饱和沸腾起始点热通量的经验关系式。结果表明：新拟合得到的关系式能较准确地预测三面加热窄矩形通道内饱和沸腾起始点的热通量,其预测值的相对误差为15.17%。将新关系式计算结果与现有实验数据进行比较,源于单面加热窄矩形通道的实验数据与新关系式符合程度较好,表明新关系式可适用于单面加热窄矩形通道。     

磁场对正丁醇-水物系汽液平衡的影响

为探讨磁场对二元共沸物系汽液平衡的影响,在不同磁感应强度的磁场中,研究了正丁醇-水物系的汽液平衡.结果表明,外加磁场对正丁醇-水物系的汽液平衡有一定的影响,总体上呈正效应,即外加磁场有利于该物系的精馏过程.采用NRTL模型对正丁醇-水物系的汽液平衡数据进行了拟合,得到了不同磁感应强度下的NRTL模型参数,并进行了热力学一致性检验,验证了试验数据的可靠性.     

三面加热窄矩形通道内饱和沸腾起始点的实验研究

以去离子水为实验介质,对截面为3 mm×43 mm的三面加热窄矩形通道内饱和沸腾(FDB)起始点进行了实验研究。分析了部分热工参数对饱和沸腾起始点的影响,对三面加热窄矩形通道内饱和沸腾起始点的数据进行非线性回归分析,得到适用于三面加热窄矩形通道饱和沸腾起始点热通量的经验关系式。结果表明:新拟合得到的关系式能较准确地预测三面加热窄矩形通道内饱和沸腾起始点的热通量,其预测值的相对误差为15.17%。将新关系式计算结果与现有实验数据进行比较,源于单面加热窄矩形通道的实验数据与新关系式符合程度较好,表明新关系式可适用于单面加热窄矩形通道。     

一定CO2浓度下压强与天然物性参数的关系

随着人类对CO2资源需求的增大,人们探究CO2与天然气物性参数的具体关系式已不可避免。本文首先从天然气的物性参数与二氧化碳含量的数据出发,以固定某一变量,结合MATLAB软件,得出其它变量之间的基本关系;然后对线性与非线性关系进行分析,从低纬度到高维度组合公式,拟合出变量之间的具体表达式;在此基础上,对此方法进行更加深入的研究,得到从一堆数据中快速得出变量之间的具体表达式。这对人们开采含一定量的CO2天然气具有重要意义。     

一定CO2浓度下压强与天然物性参数的关系

随着人类对CO2资源需求的增大,人们探究CO2与天然气物性参数的具体关系式已不可避免。本文首先从天然气的物性参数与二氧化碳含量的数据出发,以固定某一变量,结合MATLAB软件,得出其它变量之间的基本关系;然后对线性与非线性关系进行分析,从低纬度到高维度组合公式,拟合出变量之间的具体表达式;在此基础上,对此方法进行更加深入的研究,得到从一堆数据中快速得出变量之间的具体表达式。这对人们开采含一定量的CO2天然气具有重要意义。     

流动反应器催化反应转化率与温度及空速的关系式

通过实验考察了四个不同催化反应的温度T及空速Hv对流动反应器催化转化率x的影响：（1）柴油所含芳烃的加氢饱和;（2）甲醇分解制氢;（3）渣油加氢脱硫;（4）一氧化碳水煤气变换反应,研究了流动反应器中催化反应转化率x与反应温度T及空速Hv的关系。对所得实验数据进行了拟合,提出一个新的反应转化率x表达式,其中α为反映空速Hv对转化率x影响的参数．k′i（i=1,2,3）为与温度有关的系数。以此关系式对实验数据的拟合结果令人满意,平均相对误差小于2.0％。     

非中心入射流旋转圆盘水跃现象的实验与模拟

针对非中心入射流旋转圆盘,设计了利用高速摄像系统记录液膜流动的旋转圆盘装置,对圆盘表面的流体流动现象进行了研究。利用VOF（Volume of Fluid）多相流模型,建立了非中心入射流旋转圆盘进口区域气液两相流模型,并与实验测量结果进行对比,模拟值与实验值的平均相对误差为9%,证明了CFD模型的准确性。随后通过CFD方法分别研究了进口流量和圆盘旋转速度对非中心入射流旋转圆盘进口区域水跃现象的影响,结果表明在进口旋转方向前方,进口流量越大,圆盘旋转速度越小,水跃半径越大,水跃现象越明显;在进口旋转方向后方,进口流量越大,水跃半径越大,而随着圆盘旋转速度的增加,水跃半径先增大后减小。对进口旋转方向后方的水跃半径与进口流量和旋转速度的关系进行拟合,得到相关经验关联式,拟合值与模拟值的误差范围在15%以内。     

DRAG AND TORQUE ON A SLOWLY TRANSLATING DISK IN A ROTATING FLUID; EFFECTS OF A PLANE WALL, ANOTHER DISK OR A SIDE WALL

A previously presented analytical method for determining the Stokes drag on a disk sedimenting in the presence of fixed boundaries (Davis, 1990) is adapted to the case of a disk translating broadside in a rotating fluid, possibly with relative rotation. By carefully simplifying the potentially lengthy algebra, concise formulations are again developed for the cases of two disks translating together with opposite relative rotations, a disk translating towards a rigid plane that rotates with the fluid and a disk translating within a similarly rotating concentric circular container. Flows that are asymmetric allow the possibility of adjusting the relative rotation so that the disk is torque free. Values of the Taylor number, based on the disk radius, up to 50 are considered.     

Metal deposition in magnetoelectrolysis employing low frequency sine-pulse trains

The effect of uniform magnetic fields on the electrolytic deposition of copper in electric fields consisting of a d.c. bias voltage and a superimposed rectified sine-pulse train of 1 mHz-0.1 Hz frequency was investigated in an experimental cell. At appropriate combinations of magnetic flux density and potential frequency, good quality deposits can be obtained at elevated cathode current densities. Current oscillations observed under certain conditions are directly related to strong surface deterioration.     

基于有限元方法分析不同参量对裂纹漏磁场的影响

用有限元方法研究了裂纹深度、永磁体厚度、极靴间距及气隙等参量值变化对裂纹漏磁场强度和密度的影响,并给出它们的关系曲线。     

检测装置运行速度对管道漏磁检测的影响

针对天然气管道漏磁检测装置运行状态是影响检测结果准确性的重要因素,研究了漏磁检测装置不同运动状态下缺陷漏磁信号与检测装置运行速度的关系。应用有限元方法仿真分析了运动引起的电流密度变化和磁化水平变化对漏磁场的影响;并通过实验验证了仿真计算的准确性。实验结果表明:有效检测漏磁信号的检测装置运行速度范围为0~6 m/s。     

Electromagnetic coupling field strengthening of WC-TiC-Co cermet tools

This work proposes the application of pulsed electromagnetic coupling field processing (EMCFP) to enhance the lifetime and cutting performance of WC-15TiC-6Co cermet tool for the first time. Firstly, the developed electromagnetic field coupling equipment is introduced, the treatment process is analyzed, and the magnetization characteristics of WC-15TiC-6Co cermet tool are evaluated. Secondly, the strengthening effect of the EMCFP treatment is demonstrated by mechanical properties testing and cutting experiments, which reveal that the optimally treated tools exhibit a fracture toughness increased by 18%, an average cutting temperature decreased by 10%, and a friction coefficient for the rank face decreased by 7.9%. Collectively, these enhancements result in a tool lifetime increased by a factor of 1.92 relative to the lifetime of untreated tools. In addition, the results of simulation demonstrate that the simultaneously pulsed magnetic and electric fields contribute toward greater magnetic flux density and current density on the surface of the WC-15TiC-6Co cermet tool than would be obtained from the magnetic and electric fields alone.     

Non-contact mechanical property measurements at ultrahigh temperatures

The “Electro-Magnetic Mechanical Apparatus”, a novel non-contact method of mechanical testing of ultrahigh temperature ceramics at high temperatures, was developed where a mechanical stress is applied using Lorenz forces on a sample heated to high temperatures with an electric current. The design of the apparatus and an analysis relating stress to magnetic flux density, electrical current, and specimen dimensions are presented here. Significant creep deformations were observed in ZrB₂–SiC samples deformed under 20 MPa of flexural stress resulting in 0.08% strain after 240 s at 1600 °C and 0.21% strain after 150 s at 1750 °C. A fatigue load of 6 MPa at 60 Hz frequency at 1700 °C in air increased the oxidation rate. This mechanical apparatus has potential application not only for high temperature creep and fatigue experiments but also fracture and elasticity. Though developed for ceramics, this technique can be used to study high temperature mechanical properties of any conducting material.     

圆柱形橡胶试样硫化过程的有限元分析与实验研究

利用低场核磁交联密度测定仪分析不同硫化时间下橡胶材料的交联密度，并与相同时刻下盘式硫化仪测得的扭矩对比，定量地发现扭矩与交联密度近似成线性关系。通过有限元传热分析和硫化程度场分布的二次算法开发，圆柱形橡胶试样表面和芯部的温升历程和硫化程度的仿真结果与实验数据高度吻合。该研究对于橡胶制品的硫化工艺设计提供参考。     

Quantitative Analysis of Mixer‐Type Rheometers using the Couette Analogy

A procedure based on a Couette analogy, to quantitatively analyze torque/rotor speed data in order to extract viscosity/shear‐rate curves using non‐conventional geometries is presented. It is first validated using a relatively simple geometry for which the equivalent internal radius used in the analogy can be analytically obtained. The results showed that the equivalent internal radius depends only slightly on the nature of the fluid and that there is an optimal radial position r* in the analog Couette gap where the calculations can be easily performed for computing the viscosity/shear‐rate data from torque/rotational speed data. The experimental results with complex geometries and complex fluids are found to coincide, within experimental errors, with those obtained using standard geometries over a wide range of shear rates. The approach is also found to be very useful to evaluate shear‐rate and viscosity data in Couette viscometers when large gaps are used with non‐Newtonian fluids.     

磁流变液的摩擦学研究现状及展望

磁流变液的摩擦学性能对磁流变液的服役性能和耐久性能以及磁流变器件的设计和主动控制有着重要影响,在评价其性能时,应结合实际工况,将磁流变液的摩擦学性能作为一项重要指标进行考察。本文将磁流变液与电流变液和磁流体的摩擦学性能进行了对比,提出可以通过选择合适的摩擦改进剂来改善磁流变液边界润滑条件下的摩擦学性能。从两个角度综述了磁流变液的摩擦学研究现状,并指出发生在其中的边界润滑和颗粒自磨损问题严重影响磁流变液的服役性和耐久性。最后针对磁流变液摩擦学研究的不足,从设计摩擦磨损检测装置、建立流变与摩擦的联系和摩擦主动控制等角度对磁流变液的摩擦学研究在未来的进一步发展进行了 展望。