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1.
A parallel, finite-volume algorithm has been developed for large-eddy simulation (LES) of compressible turbulent flows. This algorithm includes piecewise linear least-square reconstruction, trilinear finite-element interpolation, Roe flux-difference splitting (FDS), and second-order MacCormack time marching. A systematic and consistent means of evaluating the surface and volume integrals of the control volume is described. Parallel implementation is done using the message-passing programming model. To validate the numerical method for turbulence simulation, LES of fully developed turbulent flow in a square duct is performed for a Reynolds number of 320 based on the average friction velocity and the hydraulic diameter of the duct. Direct numerical simulation (DNS) results are available for this test case, and the accuracy of this algorithm for turbulence simulations can be ascertained by comparing the LES solutions with the DNS results. For the first time, a finite volume method with Roe FDS was used for LES of turbulent flow in a square duct, and the effects of grid resolution, upwind numerical dissipation, and subgrid-scale dissipation on the accuracy of the LES are examined. Comparison with DNS results shows that the standard Roe FDS adversely affects the accuracy of the turbulence simulation. For accurate turbulence simulations, only 3–5% of the standard Roe FDS dissipation is needed.  相似文献
2.
加氢反应器分配器的数值模拟   总被引:2,自引:0,他引:2  
应用计算流体力学CFX软件对加氢反应器中联合油(Union Oil)公司的单个分配器的流场用标准k-ε方程进行了模拟,对计算结果的分析以及与型式试验结果的分析对比表明,CFX能较准确地模拟分配器气液分配时的流场。CFX可用于指导反应器内构件的研究、开发和设计。  相似文献
3.
拼接网格通量守恒插值算法研究   总被引:2,自引:0,他引:2  
提出一种通用的拼接网格通量守恒算法应用于拼接网格"找重"过程,为拼接网格预处理提供了高效、可靠的插值方法。该算法灵活利用图形学中"多边形裁剪"原理和曲线积分公式得到拼接面上相交多边形及其面积,算法实现复杂度低,简单并健壮性较好,能够通用于结构网格和非结构网格问题。实验结果表明在大网格量、复杂拼接区域时该拼接网格插值计算方法仍能得到较理想的结果。  相似文献
4.
CAE在强化传热节能减排中的应用   总被引:2,自引:0,他引:2       下载免费PDF全文
为解决管壳式换热器传热效率低下的问题,以最典型的列管式换热器为研究对象,建立换热管内置转子组合式强化传热装置的三维模型,模拟换热管内流场、温度场、压力场以及换热过程,得到管内流体的流动规律和传热性能的计算结果. 模拟计算结果显示,内置转子组合式强化传热装置的换热管内尤其是近壁区域有较强的湍流度;转子与管壁之间缝隙内的流体有明显的螺旋环绕流动,可显著提高传热系数,并具有自清洁作用. 研究表明,利用CAE手段解决热交换过程的瓶颈问题,可大幅度提高能源利用效率,为实现节能减排的战略目标作出贡献.  相似文献
5.
催化裂化汽提器的流体动力学数值模拟   总被引:2,自引:1,他引:1  
提出了一种新型填料式汽提器,并采用气固双流体模型模拟了新型汽提器和传统汽提器内气固流体流动行为.模拟结果显示新型填料式汽提器在改善颗粒流动,提高颗粒分布均匀性和汽提器空间利用率方面要优于传统盘环挡板汽提器.  相似文献
6.
飞艇动力学仿真   总被引:2,自引:1,他引:1  
刚体假设条件下,飞艇动力学行为的核心问题之一是如何获取气动导数和推进系统螺旋桨的性能参数.针对静导数,采用分块粘结技术和O型网格,生成结构化贴体网格单元,利用SST(Shear Stress Transport)湍流模型进行CFD仿真,动导数采用半经验的方法,附加质量采用边条理论计算.螺旋桨性能参数采用结构化网格与非结构化网格相结合的方法,利用旋转机械CFD软件计算.在此基础上给出了飞艇纵向静稳定性的判别方法,建立飞艇非线性动力学方程和小扰动方程.为验证上述方程,给出了纵向阶跃响应,仿真结果表明该方法是有效的,可用于飞艇后续的飞行控制研究.  相似文献
7.
Computational fluid dynamic analysis and design optimization of jet pumps   总被引:2,自引:0,他引:2  
Jet pumps have a wide variety of applications and are commonly used in thermal power plants and refrigeration systems. An initial jet-pump design was developed using an analytical approach and its efficiency was improved using an efficient and accurate computational fluid dynamics model of the compressible turbulent flow in the pump, whose predictions agreed well with corresponding experimental data. Parametric studies were performed to determine the influence of the pump’s geometry on its performance and the high fidelity CFD solutions were used to build surrogate models of the pump’s behavior using the moving least squares method. Global optimization was carried out using the surrogates. This approach resulted in pump efficiency increasing from 29% to 33% and enabled the energy requirements of the pump to be reduced by over 20%.  相似文献
8.
电泳芯片跑道效应CFD软件仿真与优化设计   总被引:1,自引:0,他引:1  
介绍了CFDRC软件的特点,利用该仿真软件以数值模拟的方式,对于弯沟道电泳芯片的跑道效应进行仿真,给出优化设计模型,分析导致电场集中的原因,探讨解决方式,研究结果为电泳芯片的实用化奠定了基础.  相似文献
9.
Efficiency of shock wave compression in a microchannel   总被引:1,自引:0,他引:1  
The efficiency of compression processes tends to decrease dramatically when the overall dimensions are scaled down to micron level. Then it can be assumed that the compression is more efficient if no moving parts are involved in the process. This is achieved by replacing, at least partially, turbo-compressor stages with a wave rotor. The work starts with estimating wave rotor efficiency at microscale by extrapolation. Then, an analytical model is introduced from which the theoretical efficiency of compression process in a microchannel is deduced. Knowing the inlet conditions and the pressure gain across the shock, the overall efficiency of the compression can be calculated. The model assumes constant friction along the walls and no heat exchange with the surroundings. The results suggest that an efficiency of 70–80% can be achieved in the channels of an ultra-micro wave rotor. It is shown that if the inlet temperature is high enough (about 1500 K), the efficiency is even higher, up to 90%.  相似文献
10.
仿生鱼鳍中形状记忆合金驱动器的水下变形精度分析   总被引:1,自引:1,他引:0  
章永华  何建慧  张世武  杨杰 《机器人》2007,29(4):320-325
简要介绍了仿生鱼鳍的基本机构和工作原理.为了提高形状记忆合金仿生鱼鳍的变形精度,理论计算了作为鱼鳍驱动器的形状记忆合金薄板对端部的水下变形误差.给出了形状记忆合金薄板表面的流体无量纲阻力系数随时间的变化关系,同时给出了某一时刻薄板表面及其周边的压力分布和薄板尾迹中的卡门涡街形态.最后,通过实验验证了理论推导的正确性.  相似文献
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