气流式水平姿态传感器数据拟合技术的研究

为了提高气流式水平姿态传感器的环境性能,将数据插值拟合方法应用在该传感器的软件温度补偿中。采用拉格朗日插值和分段线性插值法,运用Matlab软件计算并比较2种算法,把算法应用在温度补偿中,计算出温度补偿完成后零位电压值。结果表明,高次插值的runge现象使得拉格朗日数据拟合精度降低;而分段线性插值法更能准确地反映环境温度与零位电压的变化,可以为温度补偿提供精确的参考值。采用分段线性插值进行温度补偿后,环境温度的影响几乎为零,零位电压稳定在2．0V／℃,同时分段线性插值运算量少。这两点有利于提高后续补偿的精度,降低传感器的响应时间,对气流式水平姿态传感器的实用化研究和批量生产有重要意义。     

无应力组合贴片天线传感器温度性能模拟测试

基于组合式贴片天线的无源无线传感器可应用于结构形变的测量,但环境温度的变化会影响组合式贴片天线的电磁性能。针对环境温度变化影响天线传感器性能的问题,通过温度效应影响理论研究了材料温度系数(热膨胀)和介电常数变化(电磁场变化)对组合式天线谐振频率的影响规律,采用多物理场耦合方法对组合式贴片天线传感器进行了温度效应的数值模拟,对受热膨胀和基板介电常数受热变化的影响进行了量化分析。基于数值模拟明确了天线谐振频率变化的主要原因是基板受热导致介电常数变化,材料受热膨胀引起的谐振频率变化约为主因引起变化的20%,且为负相关。通过试验进一步研究温度对谐振频率的影响,将组合式贴片天线置于温箱中测定了温度梯度下谐振频率变化。模拟和试验结果均表明,随温度的升高,组合式贴片天线一阶纵向谐振频率增加,且具有线性关系,线性拟合系数均高于0.93,模型仿真平均增量预测误差小于20%。明确了该类组合式天线可采用线性温度补偿机制进行形变测量值的修正,为组合式天线传感器在实际工程应用中提供了技术基础。     

差动变压器式互感传感器测量性能分析

差动变压器式互感传感器具有既能测定物体形变大小,又能测定形变方向的良好特性,在许多场合下得到了重要应用。但由于传感器内部零点残余电压以及温度误差等因素的存在,会使传感器的测量性能受到重要影响。对此,首先分析推导了差动变压器式互感传感器的工作过程;然后通过实验对传感器的测量性能进行了验证,其中主要对影响测量性能的零点残余电压及温度变化因素进行了讨论,并给出了一些定量结果。通过该种方式的处理,可以为充分把握传感器的测量性能以及在实际中更好地应用该种传感器奠定基础。     

高精度压力传感器中温度补偿技术研究

半导体的温度特性会使压阻式压力传感器的零点和灵敏度随温度而发生漂移,是造成压力传感器测量误差的主要因素.对于高精度压力检测系统,温度漂移已成为提高其系统性能的重要障碍,在环境温度变化较大的应用领域更是如此.在分析多种温补方法优缺点的基础上,提出了一种结合多项式曲线拟合和三次样条插值的温度补偿方法,可以较好地提高测量压力...     

层状火焰中透镜效应的理论研究

燃烧场的温度与浓度的准确和及时测量是一个非常重要而又较棘手的问题,通过激光全息照片获取信息来间接测量目前是最好的方法之一.为了得到高质量的照片必须研究层状火焰的透镜效应.通过研究缝型燃烧器中预混气体燃烧气流形成层状结构,建立了其分界面的模拟曲面方程,通过对燃烧气流的光透射率和厚度灵敏因子的计算和测试,对所设计的膜系结构的各个膜层的膜层厚度进行修正,得到精确的火焰透镜焦距;然后引进光学材料的规化热差系数T和规化色差系数C,建立了无热差光学系统的方程,给出了消除环境温度和气流温度变化对其焦距的影响的设计方案.     

加速度对三维密闭腔体的温度场和流场影响的有限元分析

利用Ansys软件,通过分析加速度对三维密闭腔体的温度场和流场的影响,对气流式加速度传感器的优化设计进行探讨.采用有限元方法,通过建立三维实体模型、划分网格、加载和求解等途径,进行有限元仿真.结果表明:在流体梯度大的地方,网格划分得密一些,有助于节约计算时间和提高计算精度;利用Ansys软件的切片功能,观察不同加速度下三维密闭腔体内部的温度场和对流场的分布,与二维建模相比较,三维建模得到的计算结果更加全面和准确,为气流式加速度传感器的优化设计提供可靠的依据.     

气流式水平姿态传感器的三维建模及计算

利用ANSYS-FLOTRAN CFD软件,采用有限元方法,通过建立气流式水平姿态传感器敏感元件的三维实体模型、划分网格、加载和求解等途径,进行了有限元仿真,计算了敏感元件内部的流场,并采用了按实际尺寸比例大小建立整体模型的方法。结果表明：三维实体建模与二位平面建模相比较,这种全尺寸的三维实体建模方法可以使得计算结果更加全面准确,为气流式水平姿态传感器的实用化研究提供更加可靠完备的理论依据。     

层叛变火焰中透镜效应的理论研究

燃烧场的温度与浓度的准确和及时测量是一个非常重要而又较棘手的问题,通过激光全息照片获取信息来间接测量目前是最好的方法之一,为了得到高质量的照片必须研究层状火焰的透镜效应,通过研究缝型燃烧器中预混气体燃气流形以状结构,建立了其分界面的模拟曲面方程,通过对燃烧气流的光透射率和厚度灵敏因子的计算和测试,对所设计的模系结构的各个膜层的膜层厚度进行修正,得到精确的火焰透镜焦距,然后引进光学材料的规化热差系数T和规化色差系数C,建立了无热差光学系统方程,给出了消除环境温度和气流温度变化对其焦距的影响的设计方案。     

成人纸尿裤的内环境温度测试研究

纸尿裤的内环境直接影响穿着者皮肤的健康。为探究成人纸尿裤的内环境温度的分布和变化,利用传感器测试纸尿裤内不同部位的温度,分析实验者穿着纸尿裤后随时间的增加,温度、血压、心跳的变化。结果表明:搭口式结构的纸尿裤六分钟内温度变化小于1℃,透气性更好,适合长期卧床患者;内裤式结构的纸尿裤六分钟内温度变化达到3℃左右,透气性不好,但较贴身,适合能活动的失禁人群白天使用。纸尿裤内环境温度分布十分不匀,臀部温度最低,腹股沟随时间延长温度升高最为明显,温度变化最大。     

热线风速仪输出电压的补偿公式

温差引起的气体物性变化对热线风速仪输出电压有较大的影响，为提高热线风速仪对有传热边界条件的流场的测试精度，本文将温差与气体物性变化间的关系引入探针传热平衡方程，从而获得了一个新的温度补偿公式，并通过改变气流温度的标定试验证明其具有较高的精度．     

Design optimization of flow control device for multi-strand tundish

The fluid flow phenomena in tundish have a strong influence not only on the uniform of composition and temperature of bath, but also on the separation of non-metallic inclusions, especially for the multi-strand tundish. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of dam+weir and baffle on the uniform of composition and temperature of bath for different nozzles has been studied. The residence time distribution curves of the fluid flow were measured by SG800. Comparing the photos of the flow pattern in tundish, the optimum arrangement of baf-fle+dam was obtained. This new structure is benefit not only to uniform the temperature among different SENs (submerge entry nozzles) but also to separate the non-inclusions from the liquid steel, it can be widely used in multi-strand tundish.     

Dispersive bubble wall--a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall (DBW) is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW weir on the flow pattern has been studied. The results show that this new structure of DBW weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.     

基于底盘测功机的乘用车制动器温度场性能测试与评价

为有效评估制动器在连续下长坡后的温度场性能,设计基于底盘测功机的乘用车制动器温度场性能测试系统。首先,分析制动器的升温机理,构建基于美国NI CompactRIO平台的测试系统,并对制动液压力传感器、制动器和制动液温度传感器、制动踏板角位移和踏板力传感器进行选型,基于LabVIEW实现对测试系统采集与分析软件的快速编程;其次,考虑底盘测功机驱动模式的影响,设计升温和降温工况,构建包含整车制动器最高温度、升温速率和降温速率的评价指标对制动器温度场性能进行综合评价,并进行了实车试验。试验结果表明设计的测试系统能够稳定可靠工作,制动器温度场性能测试方法可行的。     

一种低流速气体流量传感器的研制

提出一种基于温差测量原理测量低流速气体流量的方法并进行了实验验证.传感器由一对集成温度传感器芯片与片状铂电阻热源构成,专门设计的片上恒流供电电路保证了热源加热功率的稳定.对该流量传感器样品进行测试,结果表明它能够提供与方根流速近似成线性关系的输出.在低于0.5 cm/s的低流速下,该传感器具有数十至数百毫伏的输出信号幅度,其测量下限可低至0.5 cm/s.这与理论分析结果基本相符.该流量传感器在低流速条件下具有高灵敏度和较高的稳定性.     

基于高分子乳化剂的共聚物流变行为及稳定性

考察了高分子乳化剂和小分子乳化剂共混使用对共聚物乳液流变行为和稳定性的影响规律.利用VT550旋转黏度仪研究了基于高分子乳化剂（聚乙烯醇）的丙烯酸丁酯/苯乙烯/丙烯腈三元共聚物乳液的流变特性，并分析了乳液的耐电解质(CaCl2)稳定性.实验结果表明，随着温度升高，共聚物的表观黏度下降，流动指数增大，体系黏度特性逐渐由假塑性流体向宾汉塑性流体转变.高分子乳化剂的加入明显增加了乳液体系的黏度，使得乳液流动指数增大，体系的耐电解质稳定性也大幅度提高.     

New friction factor and Nusselt number equations for laminar forced convection of liquid with variable properties

Friction factor and heat transfer coefficient of liquid flow with variable properties can significantly differ from that with constant properties. Existing equations obtained by regression analysis of experimental data use correction factors to account for variable property effect. They are limited to specific kind of fluid and low or medium temperature differences. The correction factors of the equations for heating and cooling conditions are different. New explicit friction factor and Nusselt number equations for laminar forced convection of liquid with variable properties are derived with a first order approximation of dynamic viscosity-temperature variation. The new equations are applicable to all kinds of liquids and can be used for large temperature differences. Governing equations of laminar forced convection of water and ethanol are numerically solved using computational fluid dynamics(CFD)method and the results are used to verify the derived equations. The derived equations show good predictions of friction factors and Nusselt numbers for both heating and cooling conditions and show more accurate predictions than the existing equations. A dimensionless number is also introduced based on theoretical analysis to evaluate property variation effects on friction factors and heat transfer coefficients.     

Dispersive bubble wall——a new method of flow control in tundish

Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall （DBW） is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW＋weir on the flow pattern has been studied. The results show that this new structure of DBW＋weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.     

Investigation of convection cooling guide vane with conjugate heat transfer method

This paper studied a certain blade with ten radial cooling holes which employed conjugate heat transfer method. The cooling air entered the cooling channel from the bottom of the blade and went out from the top, it was not ejected into the main flow. This paper used different numerical conditions including different turbulence models,turbulence intensities,thermal conduction coefficients and the influence on fluid property via temperature variation. The temperature distribution and pressure distribution of the blade were compared with experimental data. The results show that the numerical results using different turbulence models are almost identical to experimental data even little deviation occurs at shock wave location. The trends of temperature distribution under different numerical conditions are coincident to experimental data,especially Reynolds stress turbulence model. It can be concluded that anisotropic turbulence models can simulate the transition from laminar to turbulence,and the influence of turbulence intensity on laminar region and transition region is more than that on developed turbulent region.     

Dissymmetric flow phenomenon in a multistrand tundish

The dissymmetric flow phenomenon exists in a symmetric multistrand tundish. It was studied by the physical simulation experiment. The fundamental flow characteristic of dissymmetry was analyzed. The asymmetry of the flow field, the temperature field, and the inclusions distribution without flow-control devices (FCDs) were compared with those with FCDs. It is proved that the asymmetry of the flow and temperature field along the outlets at the long range is more obvious. The symmetric FCDs installation has a slight effect on the dissymmetric temperature field, simultaneously, the symmetry of the average residence time and the fluid flow pattern has improved, and the fluid flow in the tundish has been more reasonable. In case of a symmetric multistrand tundish having a large volume, the influence of the dissymmetric phenomenon should be considered and the flow behaviors in the whole tun- dish should be studied completely.     

数字式超声波相关流量测量研究

利用上下游流体流动噪声的相关性，提出了一种基于数字相关分析的相关流量计的设计，环境及流体自身的多种变化对流量测量精度没有任何影响．它特别适用于化工企业的多测试点的流量巡回检测工作。