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广义流体的概念在金属流动凝固传热分析模型中的应用 总被引:4,自引:0,他引:4
应用广义流体的概念,以双辊连续铸轧工艺中金属流动凝固传热现象为例,将熔池内三种状态(液相,固相和固液两相)金属流动传热过程用统一的控制方程描述。典型算例表明:熔池内存在大面积的环形流动区域,环形流动产生的搅拌效应,可以促进熔池内钢水温度与化学成分的均化,提高薄带的质量。最后,计算结果与理论分析进行了比较。该计算思想还可应用于冶金、石油工程等涉及流动凝固传热耦合问题的数值模拟研究中。 相似文献
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高温空气燃烧炉内耦合传热的数值模拟 总被引:6,自引:1,他引:5
用自行开发的三维湍流流动、燃烧、辐射传热和NOx湍流生成的计算程序,用离散坐标方法(DOM)模拟炉内的辐射传热并与其它传热方式相耦合,与各个输运方程共同求解,对燃烧室内的温度场进行了数值模拟.通过改变高温空气的预热温度,数值分析了高温空气燃烧炉内采用燃气直接喷射技术(FDI)的温度分布特性,检验了所采用的耦合数值模拟技术的有效性.模拟计算结果表明,提高空气预热温度,炉内温度的峰值相应增大,温度梯度降低,温度分布更均匀,火焰更长.相关的实验结果与数值预报的结果对比表明了相一致的规律. 相似文献
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聚变堆液态金属包层矩形管道中的氚输运过程与磁流体动力学(MHD)流动传热过程耦合在一起,形成了复杂的载氚热磁流体输运特性。基于开发的MHD流动与传热数值模拟程序对矩形管道中液态金属MHD流动传热特性及其氚输运的影响进行了数值模拟。该程序首先求解了动量守恒方程,并与理论解进行了对比验证,然后与能量守恒方程耦合求解,得到了温度影响下矩形管道中的液态金属流场分布,在此基础上对强磁场高核热梯度影响下的氚浓度分布进行了数值模拟,得到了氚浓度在管道中的分布特性。结果显示,液态金属在矩形管道中的流动传热对氚输运过程产生了显著影响。 相似文献
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针对包含近源障碍物条件下的电波传播问题,提出了一种新颖的电波传播预测混合建模方法:矩量法(MOM)和圆柱坐标系抛物方程法(PEM)混合建模方法(MOM-PEM);MOM用于包含辐射源和近源障碍物的小圆柱区域内的电波传播建模,PEM用于MOM计算空间外的大区域范围内电波传播建模。MOM和PEM的计算过渡区域进行精细化网格剖分处理以避免场强数值传递的不兼容。仿真模拟了三类近源障碍物存在场景下的电波传播问题:有限开窗屏障碍物、立方体障碍物以及包含辐射源的半封闭空间障碍物,并将混合算法计算得到的结果和相同环境下采用全矩量法计算得到的结果进行了数值对比,结果表明混合算法和矩量法在精度上吻合较好。 相似文献
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在冷气干扰下叶栅绕流的控制方程及求解方法 总被引:1,自引:0,他引:1
1控制方程高温涡轮的冷却空气量随着燃气轮机性能的提高而在不断增加,因而在数值模拟气冷涡轮流场时则须考虑喷射冷气对燃气主流的影响。本文采用文献[1]的“质量源”模型,推导出具有统一形式的适用于叶栅三维和周向平均混合流动的控制方程。在绝热和忽略粘性应力作功率条件下,将文献出中的通用形式的控制方程在柱坐标系中展开,然后再经坐标变换,将其转换到任意曲线坐标系《,刀J中,得到了在冷气干扰下的叶栅三维绕流的双曲守恒型控制方程(用矩阵形式表示):aU/&+aE/a+OF/的十OG/0(一H(1)式中仅三项含有冷气参数,… 相似文献
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用数理统计方法,推导出波动光学MTF数值计算的误差估计式,它适用于对不同的数值计算方法进行自相关积分所求得的MTF值进行误差估计.本文根据波动光学的基本性质,提出了新的MTF数值计算方法,它具有较高的数值精度,更可观的计算量大大减少. 相似文献
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光纤的数值孔径是光纤的重要参数,大数值孔径光纤在激光器和激光感应荧光系统中有很好的应用前景。光子晶体光纤的数值孔径与传统阶跃型光纤不同,它与光波长有密切的关系。因此,本文用光谱仪测量了不同结构的折射率引导型光子晶体光纤的数值孔径,并进行了数值模拟,研究了光波长、包层空气孔直径、孔间距等对光子晶体光纤数值孔径的影响,同时对光子晶体光纤的非线性系数、宏弯损耗、截止波长、有效模面积等与光波长有关的参数进行了研究,取得了满意的结果。 相似文献
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Xiufeng Yang Manjil Ray Song-Charng Kong Chol-Bum M. Kweon 《Proceedings of the Combustion Institute》2019,37(3):3279-3286
The interaction of liquid drops and heated surfaces is of great importance in many applications. This paper describes a numerical method, based on smoothed particle hydrodynamics (SPH), for simulating n-heptane drop impact on a heated surface. The SPH method uses numerical Lagrangian particles, which obey the laws of fluid dynamics, to describe the fluid flows. By incorporating the Peng–Robinson equation of state, the present SPH method can directly simulate both the liquid and vapor phases and the phase change process between them. The numerical method was validated by two experiments on drop impact on heated surfaces at low impact velocities. The numerical method was then used to predict drop-wall interactions at various temperatures and velocities. The model was able to predict the different outcomes, such as rebound, spread, splash, breakup, and the Leidenfrost phenomenon, consistent with the physical understanding. 相似文献
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We are interested in the numerical simulation of wave propagation in media which are a local perturbation of an infinite periodic one. The question of finding artificial boundary conditions to reduce the actual numerical computations to a neighborhood of the perturbation via a DtN operator was already developed in [1] at the continuous level. We deal in this article with the numerical aspects associated to the discretization of the problem. In particular, we describe the construction of discrete DtN operators that relies on the numerical solution of local cell problems, non stationary Ricatti equations and the discretization of non standard integral equations in Floquet variables. 相似文献
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An unstructured adaptive mesh flow solver, a finite element structure solver and a moving mesh algorithm were implemented in the numerical simulation of the interaction between a shock wave and a structure. In the past, this interaction is mostly considered as one-way in the sense that the shock causes a transient load on the structure while it is reflected uneffected by the impact. A fully coupled approach was implemented in the present work which can account for the effects associated with a mutual interaction. This approach included a compressible flow Eulerian solver of second order accuracy in finite volume formulation for the fluid and a Langargian solver in finite element formulation for the solid structure. A novel implementation of advancing front moving mesh algorithm was made possible with the introduction of a flexible and efficient quad-edge data structure. Adaptive mesh refinement was introduced into the flow solver for improved accuracy as well. Numerical results are further validated by theoretical analysis, experimental data and results from other numerical simulations. Grid dependency study was performed and results showed that the physical phenomena and quantities were independent of the numerical grid chosen in the simulations. The results illuminated complicated flow phenomena and structure vibration patterns, which in order to be detected experimentally require capabilities beyond those of the current experimental techniques. The numerical simulations also successfully modelled the aero-acoustic damping effects on the structure, which do not exist in previous numerical models. Further analysis of the results showed that the mutual interaction is not linear and that the non-linearity arises because the wave propagation in the fluid is not linear and it cascades a non-linear and non-uniform loading on the plate. Non-linearity intensifies when the plate is vibrating at high frequency while the wave propagation speed is low. 相似文献
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运用场匹配法和傅里叶级数理论,提出一种原则上可数值求解任意轴对称渐变型类周期慢波结构色散特性的方法。采用该方法编制了计算渐变型波纹波导和渐变型盘荷波导色散曲线的Matlab程序,详细分析并讨论了这两类典型渐变型类周期慢波结构的色散特性。数值计算结果与多维全电磁模拟软件模拟结果的数据吻合度较高,验证了该数值算法的可靠性。另外,该方法具有较强的普适性和扩展性,也可退化到任意轴对称周期慢波结构色散特性的求解,为慢波结构的设计提供一种简单有效的途径。 相似文献
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R. A. Rooth J. A. van der Pol E. H. Haselhoff 《Applied physics. B, Lasers and optics》1987,42(2):103-110
Analytical, experimental and numerical results concerning the influence of intramode and Fermi relaxation on multiple-pass, nanosecond-pulse energy extraction are presented. Multiple-pass energy extraction experiments show satisfactory agreement with the analytical and numerical calculations which predict a significant increase in extracted energy. In three passes, an amount of 9.7 J/l was extracted at an efficiency of 4.3%, These values are taken with respect to the volume of the beam inside the amplifier. In a single pass only 3.5 J/l was extracted. 相似文献