钠冷快堆(Sodium-cooled Fast Reactor,SFR)作为第四代反应堆系统的重要堆型之一,采用非能动停堆组件保证安全性已成为国内外研究共识。然而,在对非能动停堆组件落棒停堆过程进行模拟时,由于复杂几何、存在孔隙结构以及运动边界等问题...钠冷快堆(Sodium-cooled Fast Reactor,SFR)作为第四代反应堆系统的重要堆型之一,采用非能动停堆组件保证安全性已成为国内外研究共识。然而,在对非能动停堆组件落棒停堆过程进行模拟时,由于复杂几何、存在孔隙结构以及运动边界等问题的存在,传统计算流体力学(Computational fluid dynamics,CFD)程序所使用的结构化网格或非结构化网格生成方法在解决该类问题时存在较大的局限性。本文基于浸没边界法开发了相应的求解程序,该法无需构建复杂的贴体网格,而是采用简单的笛卡尔网格,通过将体积力添加到控制方程中的方式纳入边界条件,适合上述工况的模拟过程。并对程序的准确性进行验证分析,分别模拟了在二维固定圆柱绕流下的稳态流动、不稳定流动,以及二维振荡圆柱不稳定流动,得到涡旋特征参数、阻力系数、升力系数、斯特劳哈尔数,以及涡脱落情况等数值模拟结果,并将其与已有文献数据进行对比,结果显示本求解器具有良好的效率和准确性。展开更多
The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and th...The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3?9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals,it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble.展开更多
文摘钠冷快堆(Sodium-cooled Fast Reactor,SFR)作为第四代反应堆系统的重要堆型之一,采用非能动停堆组件保证安全性已成为国内外研究共识。然而,在对非能动停堆组件落棒停堆过程进行模拟时,由于复杂几何、存在孔隙结构以及运动边界等问题的存在,传统计算流体力学(Computational fluid dynamics,CFD)程序所使用的结构化网格或非结构化网格生成方法在解决该类问题时存在较大的局限性。本文基于浸没边界法开发了相应的求解程序,该法无需构建复杂的贴体网格,而是采用简单的笛卡尔网格,通过将体积力添加到控制方程中的方式纳入边界条件,适合上述工况的模拟过程。并对程序的准确性进行验证分析,分别模拟了在二维固定圆柱绕流下的稳态流动、不稳定流动,以及二维振荡圆柱不稳定流动,得到涡旋特征参数、阻力系数、升力系数、斯特劳哈尔数,以及涡脱落情况等数值模拟结果,并将其与已有文献数据进行对比,结果显示本求解器具有良好的效率和准确性。
基金Project(NCET-05-0413)support by the Program for New Century Excellent Talents in UniversityProject(YB0142112) support by Priming Foundation of East China University of Science and Technology
文摘The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3?9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals,it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble.
