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1.
小孔节流气体静压润滑的离散化和计算收敛   总被引:22,自引:6,他引:16       下载免费PDF全文
刘暾  彭春野 《摩擦学学报》2001,21(2):139-142
通过在雷诺方程式中增加一流量项,以避免求解雷诺方程时,为满足流量条件而求解压力梯度所带来的噪声和误差,并将不同坐标系内的雷诺方程式变换成为相同形式,以简化数值计算;对加权余量法和变分求极值法这2种将微分方程离散化的方法进行了分析;探讨了小气膜时出现发散的原因并提出了应对措施。  相似文献
2.
船用加筋板架爆炸载荷下动态响应数值分析   总被引:15,自引:0,他引:15  
针对船用加筋板架复杂结构在爆炸冲击波作用下的动态响应,采用商用高动态非线性有限元程序MSC/Dytran,讨论了大尺寸加强结构板架迎爆承载问题,提出了复杂板架结构爆炸冲击波作用下动态响应的有限元计算方法,并进行了模型试验.试验结果与计算结果吻合较好,验证了应用程序及计算模型参数的稳定性和可靠性.对加筋板架两种承载形式(大尺寸加强构件迎爆或背爆设置)在爆炸冲击波作用下的动态响应(板架中心挠度和塑性分布)差异的分析研究表明,大尺寸骨架(纵骨和肋骨)背向爆炸冲击波设置将分散爆炸冲击波的冲击作用、减小板架变形、增强其抵抗爆炸冲击波冲击的能力,使结构偏于安全.  相似文献
3.
非理想爆源爆炸波的数值计算   总被引:13,自引:0,他引:13  
丁云  丁大玉 《爆炸与冲击》1995,15(4):289-299
采用均匀能量加入模型,对非理想爆源爆炸所产生的爆炸波进行数值计算,数值解与实验结果吻合较好。  相似文献
4.
高速列车外形的气动性能数值计算和头部外形的改进   总被引:7,自引:0,他引:7  
运用流体力学数值计算软件CFX对我国200km/h电动旅客列车的空气动力性能进行了数值模拟计算,针对列车气动外形存在的问题,对列车头部外形进行了改进,并提出了三种列车头部外形改进方案且对其进行了数值模拟研究。计算结果表明,方案三优于其它两种方案,且较改进前列车的空气动力性能有了较大改善。  相似文献
5.
The particle dispersion characteristics in a confined swirling flow with a swirl number of approx. 0.5 were studied in detail by performing measurements using phase-Doppler anemometry (PDA) and numerical predictions. A mixture of gas and particles was injected without swirl into the test section, while the swirling airstream was provided through a co-flowing annular inlet. Two cases with different primary jet exit velocities were considered. For these flow conditions, a closed central recirculation bubble was established just downstream of the inlet.

The PDA measurements allowed the correlation between particle size and velocity to be obtained and also the spatial change in the particle size distribution throughout the flow field. For these results, the behaviour of different size classes in the entire particle size spectrum, ranging from about 15 to 80 μm, could be studied, and the response of the particles to the mean flow and the gas turbulence could be characterized. Due to the response characteristics of particles with different diameters to the mean flow and the flow turbulence, a considerable separation of the particles was observed which resulted in a streamwise increase in the particle mean number diameter in the core region of the central recirculation bubble. For the lower particle inlet velocity (i.e. low primary jet exit velocity), this effect is more pronounced, since here the particles have more time to respond to the flow reversal and the swirl velocity component. This also gave a higher mass of recirculating particle material.

The numerical predictions of the gas flow were performed by solving the time-averaged Navier-Stokes equations in connection with the well known kε turbulence model. Although this turbulence model is based on the assumption of isotropic turbulence, the agreement of the calculated mean velocity profiles compared to the measured gas velocities is very good. The gas-phase turbulent kinetic energy, however, is considerably underpredicted in the initial mixing region. The particle dispersion characteristics were calculated by using the Lagrangian approach, where the influence of the particulate phase on the gas flow could be neglected, since only very low mass loadings were considered. The calculated results for the particle mean velocity and the mass flux are also in good agreement with the experiments. Furthermore, the change in the particle mean diameter throughout the flow field was predicted approximately, which shows that the applied simple stochastic dispersion model also gives good results for such very complex flows. The variation of the gas and particle velocity in the primary inlet had a considerable impact on the particle dispersion behaviour in the swirling flow and the particle residence time in the central recirculation bubble, which could be determined from the numerical calculations. For the lower particle inlet velocity, the maximum particle size-dependence residence time within the recirculation region was considerably shifted towards larger particles.  相似文献

6.
一种减轻固粒对壁面冲蚀磨损的新方法   总被引:6,自引:1,他引:5       下载免费PDF全文
针对带固粒的近壁流场,提出了在壁面上开凿纵向浅沟槽以减轻固粒对壁面冲蚀磨损的方法.采用改进的κ-ε湍流模式和气-固两相双向耦合模型,计算了流场中颗粒的速度、轨迹以及固粒对壁面的冲蚀磨损,并进行了相应的试验对比.结果表明:在壁面上开凿纵向沟槽能减轻固粒对壁面的磨损;在一定的沟槽高度下,当沟槽宽度同沟槽问距离相等时,减轻磨损的效果最明显;在一定颗粒尺寸范围内,大颗粒导致磨损质量损失增大,当颗粒尺寸超过某一临界值后,颗粒尺寸对磨损的影响较小.进口处颗粒运动方向对壁面磨损具有直接影响.  相似文献
7.
数值研究平板方舵激波-湍流边界层干扰   总被引:4,自引:0,他引:4  
邓小刚  张涵信 《力学学报》1993,25(6):651-657
数值研究了平板方舵激波-湍流边界层干扰流场,模拟出了分离激波与弓型激波碰撞后形成的“λ”激波结构;清晰地显示了分离区中的旋涡结构,发现流场中会出现二次分离涡,并从理论上分析了流场对称面涡心形态与非定常的关系,得到了涡心为不螺旋点或出现极限环是非定常流动特征的新结论。  相似文献
8.
压电材料平面裂纹尖端场的杂交应力有限元分析   总被引:4,自引:1,他引:3  
周勇  王鑫伟 《力学学报》2004,36(3):354-358
基于复势理论和杂交变分原理建立了一种适用于力电耦合分析的杂交应力有限元模型.给出了建立刚度矩阵的主要公式和推导过程,单元内的位移场和应力场采用满足平衡方程的复变函数级数解,假设的复变函数级数解事先精确满足裂纹的无应力和电位移法向分量为零的条件,单元外边界的位移场假设按抛物线变化,单元的刚度矩阵采用Gauss积分的方法得出.通过对力电耦合裂尖场的数值计算验证了程序的正确性和单元的有效性,同时也用所得结果校验了理论解.  相似文献
9.
The round-off error introduces uncertainty in the numerical solution. A computational uncertainty principle is explained and validated by using chaotic systems, such as the climatic model, the Rossler and super chaos system. Maximally effective computation time (MECT) and optimal stepsize (OS) are discussed and obtained via an optimal searching method. Under OS in solving nonlinear ordinary differential equations, the self-memorization equations of chaotic systems are set up, thus a new approach to numerical weather forecast is described. The project supported by the National Natural Science Foundation of China (40275031 and 40231006), the National Key Program for Developing Basic Sciences (G1999043408) and the Key Innovation Project of Chinese Academy of Sciences (K2CX1-10-07)  相似文献
10.
本文提出了一个新的杂交格式,它将Steger-Warming的矢通量分裂与Harten的TVD格式紧密结合在一起,构造了一个高分辨率的新格式,用于计算跨声速流场和捕获激波。典型的定常跨声速叶栅流算例表明:当Courant数取6~100时,一般在90步内残差的二范数下降三个数量级,这样的收敛率要比Beam-Warming格式快得多;观察残差的收敛历史发现:收敛曲线并无大的波动;分析激波附近的数值结果,没出现“低亏,过跳”、伪振荡现象,叶盆和叶背面上激波前或激波后的参数无波动;在60×15网格下捕获的激波过渡区不超过2个网格,表明了该格式具有较高的分辨率,能在不人为附加耗散项的条件下给出高质量无数值波动的激波流场解。  相似文献
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