共查询到20条相似文献,搜索用时 93 毫秒
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利用幂律流体的本构方程建立了幂律流体在斜齿齿轮泵间隙中的泄漏模型,并得到了最佳间隙的隐函数式及摩擦功率,同时给出实例并进行了数值计算。研究结果为聚合物齿轮泵的间隙优化设计及漏流特性提供了重要的理论依据。 相似文献
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动涡旋盘的轴向串动间隙对涡旋压缩机的工作性能影响极大,为了确定其最佳值,利用一种动盘轴向间隙的可调结构,通过实验测得了不同间隙值下的容积效率、比功率和机械效率等性能参数的大小,分析了这些参数的变化规律,确定了最佳动盘轴向间隙值,对涡旋压缩机的设计具有一定的指导意义。 相似文献
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指出了离心空压机气封轴向间隙存在的问题及造成的危害。根据实例分析了轴向间隙的影响因素,提出了解决轴向间隙不合理的方法。 相似文献
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低滞后刷式密封泄漏流动数值模拟及结构优化 总被引:4,自引:0,他引:4
基于多孔介质模型,采用计算流体力学软件Fluent对常规、低滞后矩形及翼型3种刷式密封泄漏流动特性进行数值模拟,结果表明:相比于常规刷式密封,矩形刷式密封迟滞性并没有得到改善,翼型刷式密封在降低迟滞性的同时泄漏量却大大增加。为改进低滞后刷式密封的性能,提出背板轴向间隙的概念,并研究背板轴向间隙对低滞后刷式密封泄漏流动特性的影响,结果表明:在前后压比一定的条件下,泄漏量与轴向间隙成正比,而泄漏增加量与轴向间隙成反比,且均在轴向间隙较小时变化较明显;相较于矩形刷式密封,轴向间隙密封随着轴向间隙的增大,背板处压力值除在保护高度区域内略有提高外,在其他区域均明显下降,且轴向间隙由0增大到0.1 mm时的压力下降效果最明显。 相似文献
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不确定环境下再制造发动机曲轴轴向间隙优化控制 总被引:1,自引:1,他引:0
再制造发动机曲轴轴向间隙既是影响再制造发动机性能的重要因素,也是不确定环境下再制造发动机装配过程质量控制的难点。以再制造发动机装配过程中曲轴轴向间隙优化控制为研究目标,分析不确定环境下再制造发动机曲轴轴向间隙影响因素,并构建基于信息熵的装配尺寸不确定测度模型,进而研究再制造发动机装配过程中曲轴轴向间隙质量耦合内在关系;在确保再制造发动机曲轴轴向间隙装配尺寸熵不大于新品的前提下,通过数学公式推导出再制造曲轴第一轴颈宽度和缸体轴承座宽度分级选配尺寸公差宽放系数;提出基于分级选配的再制造发动机曲轴轴向间隙优化控制方法;通过某再制造发动机企业的实例验证了该方法的有效性和可行性。 相似文献
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轴向绕组磁流变液阻尼器的磁场特性分析 总被引:1,自引:0,他引:1
运用ANSYS有限元分析软件,针对轴向绕组结构的磁流变液阻尼器,建立电磁场有限元计算模型,分析阻尼间隙通道的磁场特性,并建立径向线圈磁路结构的电磁场有限元模型,分析径向结构的阻尼间隙通道的磁场分布特性,对比有限元理论分析得出轴向绕组结构能在阻尼间隙通道产生近似平行平板磁场特性的均匀磁场.然后对轴向绕组结构在阻尼间隙通道产生的磁场进行测试,试验得出轴向绕组结构的阻尼器间隙通道磁场特性优良,更有利于磁流变效应;试验结果与理论分析基本一致,有限元分析方法为轴向绕组阻尼器的理论研究提供了方法参考. 相似文献
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航空发动机低压涡轮带冠叶片篦齿和机匣之间的叶尖间隙参数以及篦齿轴向窜动参数的在线高精度测量是保证涡轮发动机安全运作和气动效率的关键。传统的电容式叶尖间隙测量系统对噪声敏感度大,且不能对篦齿的轴向窜动参数同时进行测量。因此研制了一种“人”字形电容传感器,提出了一种基于频谱的篦齿叶尖间隙参数和轴向窜动参数的提取方法。建立了“人”字形电容传感器测量模型。仿真分析了测量信号的幅度谱特征并提出了一种最优谱线选择方法。提出了基于转速和信号特征频率估计的自适应频域滤波,信号整周期等角度采样,幅度谱估计以及二元多项式曲面拟合相融合的信号处理方法,实现了叶尖间隙参数和轴向窜动参数的动态测量。在实验室环境下搭建了篦齿叶尖间隙参数和轴向窜动参数测试实验平台,完成了标定和测量实验。实验结果显示,篦齿盘工作在1 900 r/min以下时,测量系统在0.5~1.5 mm叶尖间隙及±1 mm轴向窜动范围内,叶尖间隙测量精度达18μm,轴向窜动测量精度达30μm。 相似文献
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Experimental investigations have been carried out to determine the drag reduction produced by polymer additives in coal water mixture (CWM) and hydraulic tranports. Different values of flow velocities, polymer concentrations and different temperatures were adopted to obtain a clear picture about the process involved. The additives are polyox WSR-301 and separan AP-273 in coal and deionized water mixtures. The experiments were undertaken with a test section pipe diameter 9.8mm and lenght 3500mm in a closed loop. The criteria used is to produce the amount of drag reduction and have the stability against degradation with reliable polymer additives. It is found that the drag reduction on CWM containing polymer is greater at higher flow velocities and in “pure” polymer solutions than CWM containing polymer. Furthermore, polymer concentrations at which drag reduction reached a maximum have been investigated. 相似文献
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堆叠式高分子材料椎体扩张器前端的高分子管在工作状态下受轴向压力堆叠成"高分子团"以扩张塌陷椎体,高分子团的形状和尺寸直接影响椎体后凸成形手术的质量和效果。因此研究高分子管管壁切缝尺寸及分布与由其堆叠而成的高分子团尺寸、形状之间的关系,是椎体扩张器研发的关键问题之一。通过建立数学模型,推演出手术要求的高分子团的规格与高分子管管壁上切缝的尺寸及分布的规律,得出数学计算公式,并举例验证了切缝尺寸计算公式和分布规律的正确性,从而提高椎体扩张器的工作可靠性和效果可预测性。 相似文献
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In polymer composites the interaction between polymer matrix and filler particles often results in nucleation of spherulites. The principles of polymer crystal nucleation and spherulite growth are investigated using scanning transmission electron microscopy (STEM) and microdiffraction techniques in combination with polarized light microscopy. Simultaneous diffraction patterns from the interface of the filler and the polymer were obtained. Special precautions for successful recording of the diffraction patterns were used to overcome the rapid loss of polymer crystallinity, resulting from electron beam damage. Analysis of the diffraction patterns has shown that partial epitaxial correlation between the atomic periodicity of the particle surface and the molecular periodicity of polymer chains is always present when spherulites are nucleated. STEM images show that only large particles, with well developed facets (cleavage planes), are nucleating. The nucleating efficiency of the filler is therefore dependent on the size as well as on the crystallographic orientation of the facet. Small particles, or those with no suitable facets, do not affect the crystalline structure of the polymer. It is also shown that anisotropic polymer structures can be formed by inhomogeneous dispersion of nucleating filler particles. 相似文献
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A molecular dynamics simulations model of nanoimprint lithography (NIL) is proposed in order to study the pattern transfer
and its related phenomena. The proposed model is similar to a real NIL process imprinting an α-quartz stamp with a rectangular
line pattern into an amorphous poly-(methylmethacrylate) (PMMA) film. The polymer deformation behavior and the adhesion and
friction effects between the stamp and the polymer film are investigated and their dependency on the pattern aspect ratio
is discussed. Force fields including bond, angle, torsion, van der Waals, and electrostatic potentials are used to describe
intermolecular and intramolecular interacting forces. Nosé-Hoover thermostat is used to control the temperature of the polymer
film and cell multipole method is adopted to treat long range interactions. The deformation of the polymer film is observed
for two stamps having different aspect ratio patterns. The distributions of density and stress in the polymer film are calculated
for the detail analysis of deformation behavior. For a high aspect ratio pattern (aspect ratio = 2.5, imprint depth = 8.0 nm),
large amount of springback of the residual polymer film is observed, which is mainly due to the residual compressive stress
left in the polymer film. However, for a low aspect ratio pattern (aspect ratio = 1.0, imprint depth = 3.0 nm), the springback
is not observed. In addition, adhesion and friction forces are obtained by dividing the polymer film into subregions and calculating
the interacting force between each subregion and the stamp. While the adhesion force is nearly constant regardless of the
pattern aspect ratio, the friction force increases as the pattern aspect ratio grows, so the friction force becomes larger
than the adhesion force when the pattern aspect ratio increases. 相似文献
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This paper investigates the thermomechanical formation and recovery of nanometer-scale indents in a shape memory polymer (SMP), studied using a heated atomic force microscope (AFM) tip and hot-stage atomic force microscopy. The material tested is a tert-butyl acrylate (tBA)-based polymer, which has a glass transition temperature of 60 degrees C. The AFM tip forms indents in the polymer in the temperature range 25-250 degrees C. The shape recovery of the indents is studied while the polymer is heated up to 100 degrees C. The temperature required for complete annealing of the indents depends upon the indentation formation conditions, with higher temperature formation corresponding to higher temperature recovery. 相似文献
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基于硅桥的新型甲醛气体传感器的研究 总被引:1,自引:0,他引:1
提出了一种基于高分子薄膜溶胀效应的新型MEMS压阻式甲醛气体传感器,其结构由嵌入惠斯通电桥的硅桥和一层改性丙烯酸酯气敏薄膜构成,敏感薄膜因吸收甲醛气体发生溶胀使硅桥上的惠斯通电桥产生输出电压,从而实现对甲醛气体的检测.基于弹性力学薄板原理构建了该气体传感器中硅桥与改性丙烯酸酯薄膜相互作用的模型,并推导出传感器的输出公式.实验结果验证了理论分析模型,实验结果表明该传感器有很好的线性,选择性.实验测得该传感器灵敏度为0.975×106ecr,分辨率为10×10-6,响应时间和恢复时间分别为50s和65s.该传感器结构简单、无须加热,工艺成熟、成本低,应用MEMS 工艺技术可实现与信号处理电路的集成. 相似文献