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紧致方法对流动换热及静态分岔的模拟 总被引:1,自引:0,他引:1
发展了基于投影法的紧致方法求解流动换热问题,对顶盖驱动流和侧壁加热的方腔内自然对流换热问题进行了数值模拟。与其它传统方法相比,紧致方法能在较少的网格结点下获得精度较高的计算结果。进一步,采用所发展的紧致方法对不同工况下的Rayleigh-Benard对流及其静态分岔现象进行了数值模拟。数值计算结果表明当长宽比变大时,底部努塞尔数会有小幅度增加。当长宽比为8时,用所发展的紧致方法不同的初场可以得出三种不同的流场和温度场。与基于QUICK格式的SIMPLE算法相比,所发展的紧致方法可以多预测一种静态分岔现象。 相似文献
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空间遥感器调焦机构组件动特性分析 总被引:3,自引:1,他引:2
为了研究某种空间遥感器调焦机构组件的动特性,对其进行了锤击法模态试验。通过采用有限元分析软件MSC/NASTRAN对空间遥感器调焦机构组件进行模态分析,得到了空间遥感器调焦机构组件的低阶固有振动频率和主振型。对空间遥感器调焦机构组件试验模态与计算模态进行了对比,并进行了相关性分析和评估。通过空间遥感器调焦机构组件试验模态与计算模态的对比可知:前四阶的固有频率相对误差均在5%以内;模态置信准则判据(MAC)的值均在0.95左右;模态贡献因子(MPF)的值均在0.9左右。说明空间遥感器调焦机构组件计算模态与试验模态具有比较好的相关性,有限元模型比较准确地反映了实际的空间遥感器调焦机构组件的动特性,并为空间遥感器调焦机构的进一步设计提供了依据。 相似文献
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一类各项异性半线性椭圆方程自然边界元与有限元耦合法 总被引:1,自引:0,他引:1
将冯康和余德浩提出的自然边界归化方法用于研究一类半线性椭圆方程外区域问题,提出一种自然边界元与有限元的耦合算法、针对某一类半线性椭圆方程,应用变分原理,研究其弱解性及Galerkin逼近,得到有限元解的误差估计及收敛阶O(h^n),最后给出相应数值例子。 相似文献
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Vibrational characteristics in small horizontal axis wind turbine system are presented in this study with a system concept called tactile response and substructuring. The main focus is on managing the dynamic properties like vibration, noise, and harshness that occur during the operational mode. Tactile response is defined as the response of subsystem which is induced when a human body touches a vibrating system. Sub structuring is a computational method used to reduce the dynamic behavior of a large complex system with a smaller number of degrees of freedom without disturbing the mesh size of the model. Sub structuring has the ability to combine numerical results along with the experimental results. Combination of substructuring and tactile response is applied in this study. Mode shapes of the system are analyzed and results obtained are correlated within this study to provide better optimization of the results. Wind turbine excited with wind energy depends on wind speed. Torsional vibration has a significant role in determining dynamic properties. Torsional vibration is caused as a result of the rotation of the turbine blade and depends on wind speed. The study gives importance to investigating the ability to simulate the numerical method and tactile response to predict and improve dynamic properties. 相似文献
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A 162.5 MHz, 2.1 MeV radio frequency quadruples (RFQ) structure is being designed for the Injector Scheme Ⅱ of the China Accelerator Driven Sub-critical System (C-ADS) linac. The RFQ will operate in continuous wave (CW) mode as required. For the CW normal conducting machine, the heat management will be one of the most important issues, since the temperature fluctuation may cause cavity deformation and lead to the resonant frequency shift. Therefore a detailed multi-physics analysis is necessary to ensure that the cavity can stably work at the required power level. The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and this process will be iterated for several cycles until a satisfactory solution can be found. As one of the widely accepted measures, the cooling water system is used for frequency fine tunning, so the tunning capability of the cooling water system is also studied under different conditions. The results indicate that with the cooling water system, both the temperature rise and the frequency shift can be controlled at an acceptable level. 相似文献
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A novel method for the static analysis of structures with interval parameters under uncertain loads is proposed, which overcomes the inherent conservatism introduced by the conventional interval analysis due to ignoring the dependency phenomenon. Instead of capturing the extremum of the structural static responses in the entire space spanned by uncertain parameters, their lower and upper bounds are calculated at the minimal and maximal point vectors obtained dimension by dimension with respect to uncertain parameters based on the Legend orthogonal polynomial approximation, overcoming the potential engineering insignificance caused by the optimization strategy. After performing its theoretical analysis, both the accuracy and applicability of the proposed method are verified. 相似文献
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紫外-可见吸收光谱法不仅可以应用于分析藻胆蛋白种类以及纯度,还可以用于分析并指导其提取纯化过程。以巢湖新鲜蓝藻为实验原料,以CellufineA-500与羟基磷灰石为填料,运用柱层析法精致纯化藻蓝蛋白和别藻蓝蛋白;根据两种填料对应的洗脱峰在洗脱曲线上的特点,充分利用藻红蛋白、藻蓝蛋白、别藻蓝蛋白与核酸、类胡萝卜素、一般蛋白质的紫外-可见光谱特性的差别,研判洗脱峰组分与含量的动态变化。通过紫外-可见吸收光谱法分段研究两种填料柱层析法精致纯化藻胆蛋白洗脱峰的光谱学特征及其变化规律,能够定性定量地判断出各洗脱峰的组分和含量变化;结合两种填料的特性,能够分析出藻蓝蛋白、别藻蓝蛋白、藻红蛋白等的电荷特性与配位能力强弱,从而揭示两种柱层析填料分段洗脱的内在机理和本质。在CellufineA-500纯化藻胆蛋白过程中,随着洗脱液的更换,洗脱曲线上会出现4个洗脱峰,经扫描取样点的紫外-可见吸收光谱分析后发现:Ⅰ峰主要成分为带正电荷或电中性的杂蛋白与类胡萝卜素;Ⅱ峰主要成分为带少量负电荷的藻红蛋白、杂蛋白与核酸;Ⅲ峰主要成分为带有较多负电荷的高纯度藻蓝蛋白及少量别藻蓝蛋白,且由于藻蓝蛋白与别藻蓝蛋白未能完全分离,制约了藻蓝蛋白纯度的进一步提高;Ⅳ峰主要成分为带有大量负电荷的杂蛋白与低纯度藻蓝蛋白。在羟基磷灰石纯化藻胆蛋白过程中,随着洗脱液的更换,洗脱曲线上出现3个洗脱峰,经扫描取样点的紫外-可见吸收光谱后发现:Ⅰ峰主要表征为阳离子或碱性蛋白质的杂蛋白、核酸与类胡萝卜素成分等;Ⅱ峰主要表征为与钙离子结合生成较弱配位键的高纯度藻蓝蛋白成分,且由于藻蓝蛋白与别藻蓝蛋白能完全分离,有利于藻蓝蛋白纯度的进一步提升;Ⅲ峰主要表征为与钙离子结合生成较强配位键的高纯度别藻蓝蛋白成分。 相似文献
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A 162.5 MHz, 2.1 MeV radio frequency quadruples (RFQ) structure is being designed for the Injector Scheme Ⅱ of the China Accelerator Driven Sub-critical System (C-ADS) linac. The RFQ will operate in continuous wave (CW) mode as required. For the CW normal conducting machine, the heat management will be one of the most important issues, since the temperature fluctuation may cause cavity deformation and lead to the resonant frequency shift. Therefore a detailed multi-physics analysis is necessary to ensure that the cavity can stably work at the required power level. The multi-physics analysis process includes RF electromagnetic analysis, thermal analysis, mechanical analysis, and this process will be iterated for several cycles until a satisfactory solution can be found. As one of the widely accepted measures, the cooling water system is used for frequency fine tunning, so the tunning capability of the cooling water system is also studied under different conditions. The results indicate that with the cooling water system, both the temperature rise and the frequency shift can be controlled at an acceptable level. 相似文献
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A full-wave modal analysis of two-dimensional, lossy and anisotropic optical waveguides using the finite element method (FEM) is presented. In order to describe the behavior of radiating fields, anisotropic perfectly matched layer boundary conditions are applied for the first time in modal solvers. The approach has been implemented using high order edge elements. The resulting sparse eigenvalue algebraic problem is solved through the Arnoldi method. Application to an antiresonant reflecting optical waveguide is reported. 相似文献
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针对某小型液压挖掘机驾驶室低频噪声过大问题,对驾驶室结构振动特性进行分析。基于有限元模型计算各工况下驾驶室噪声传递函数,运用统计学方法确定主要噪声峰值频率及相应工况;通过模态声学贡献度计算,确定危险工况下噪声贡献量较大的模态阶数,参照模态振型确定驾驶室振动变形最大的车身板件;并对该板件进行形貌优化处理,提高其一阶固有频率,进而降低驾驶室内噪声。优化结果表明,驾驶室噪声传递函数在危险频率下的峰值下降了2~4 dB。 相似文献
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B. M. Azizur Rahman A. K. M. Saiful Kabir Muttukrishnan Rajarajan Kenneth T. V. Grattan 《Optical and Quantum Electronics》2005,37(1-3):171-183
Modal solutions of planar photonic crystal waveguides with rectangular air-holes are presented by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations. 相似文献
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模态分析可以获得结构的动特性参数。对32级模块化Marx发生器机芯进行了力学特性仿真分析和模态试验,用以评估Marx发生器的力学环境适应性。首先,建立了模块化Marx机芯的有限元模型,获得了初步振型;其次,在自由边界条件下分别开展了Marx机芯整体模态试验、局部模态试验和传递特性试验,得到了整体和局部结构的模态参数。研究表明,模块化Marx机芯在23.58 Hz处出现整体一阶扭转;机芯局部结构固有频率较高;机芯在x,y,z三个方向的振动传递率的范围分别为5~15,6~10和10~35,为后续工程中Marx发生器机芯的针对性设计提供了参考。 相似文献
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用子结构模态综合法求解光学反射镜组件结构动响应 总被引:2,自引:1,他引:1
在航天光学成像仪器中光学反射镜组件结构复杂,相应的有限元分析模型大,因此分析效率较低。针对此问题,引入子结构模态综合法作为光学反射镜组件结构动响应的求解方法。具体讨论了子结构模态综合法求解结构动响应的基本原理,说明了该法在工程上的实现方法。以某反射镜组件为例进行了计算,结果表明,子结构模态综合法与经典的整体FE分析法比较,求解的前10个固有频率误差小于7%,计算时间前者为后者的2/3;加速度响应曲线符合良好,计算时间前者为后者的2/5,子结构模态综合法的计算效率明显提高,工程适用性良好。 相似文献
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理论上分析了静动结合的化学腐蚀法制备探针的具体机理及过程。在静态腐蚀的过程中, 利用流体力学Young-Laplace方程的一级近似解获得了光纤插入到HF酸中形成的新月形高度。在动态腐蚀过程中, 详细分析了当静态腐蚀时间和动态腐蚀时间分别取不同值时, 光纤移动速度对光纤探针结构的影响。利用此法可制备出尖端锐利、大锥角或多锥体等各种结构的光纤探针。这为实验上制备出性能优良的探针, 为拓宽扫描近场光学显微镜的应用范围奠定基础。将上述理论分析的结果与本文实验中所得初步结果进行了比较, 所得结果一致。 相似文献