【作者】 刘春艳；

【导师】 程宏志；

【作者基本信息】 煤炭科学研究总院 ， 矿物加工工程， 2009， 硕士

【摘要】 XJM-S系列浮选机是广泛应用于选煤生产的一种机械搅拌式浮选机,利用计算流体力学软件FLUENT模拟分析了XJM-S8型浮选机的流场特性。应用PRO/E软件建立了浮选机实体三维模型,应用GAMBIT软件对流场计算域进行网格划分,采用有限体积法作为离散化方法,选用标准k-ε湍流模型,以清水为介质,模拟分析了浮选机流场特性。通过数值模拟,得出了叶轮-定子区域压力分布图,浮选槽内不同剖面上液体流线图、速度分布图,以及湍动能、湍流强度、湍流耗散率等特征参数的分布状态及其变化规律。通过对叶轮-定子区域的模拟分析,发现在叶轮相同半径处叶片背液面动压总是高于迎液面,表明背液面流速高于迎液面流速;当流体进入定子时,受定子叶片阻碍作用速度下降,动能转换为压能;叶片流道中动压、静压、全压的最大值分别为36.6kPa、28.9kPa、60.4kPa,最小值分别为3.0kPa、-35.3kPa、-31.2kPa;在叶轮区域内流体的最大速度为8.56m/s,接近于叶轮圆周速度8.9m/s。通过对浮选槽内流体的流线图分析,发现流动状态呈“W”形立体循环运动,下部为纵向涡流运动,上部流动平稳,符合浮选过程要求;液流通过定子后,在稳流板导向作用下沿水平断面分布均匀,无死区,浮选机结构合理。通过对湍流特征参数的分析,发现湍动能、湍流强度、湍流耗散率关于叶轮中心呈对称分布;XJM-S8型浮选机的搅拌区域在槽体下部0.7m以下,在0.7m以上部分处于相对平稳的浮选分离区域,搅拌区域的湍流强度约为浮选分离区域的6倍;湍流强度与叶轮圆周速度成正比,以叶轮圆周速度恒定作为XJM-S型浮选机模拟放大运动相似准则,可保证相似的湍流强度。通过浮选机流场数值模拟分析,对XJM-S型浮选机的流场特征有了比较深刻的认识,为该类型浮选机的研究与优化设计奠定了一定理论基础。更多还原

【Abstract】 XJM-S series flotation cell is a kind of mechanical-stirring type flotation machine, which is widely applied in coal preparation. In this paper, Fluid Mechanics software FLUENT was used to analyze the fluid field characteristics of the XJM-S8 flotation cell. And software PRO/E was applied to set up 3-D entity model. While software GAMBIT was served for grid partition in the calculation region. This paper adopted finite volume method as discretization method, selected the standard k-εturbulent flow model as well as used pure water as medium to simulate and analyze the characteristics of the flotation cell. By numerical simulation, the pressure distribution of the impeller-stator region, the streamline diagram as well as the speed distribution graph of the liquid at different sections within the flotation cell could be obtained. In addition, the distribution and the evolution pattern of the turbulent kinetic energy, turbulence intensity, turbulence dissipation rate and other characteristics parameters could also be gained. Through the impeller-stator region simulation analysis, it was found that, at a certain radius of the impeller blade, the dynamic pressure against the liquid surface was always higher than that on the liquid surface, indicating that the liquid flow velocity against surface was higher than that on the liquid surface; When the fluid entered the stator, the speed decreased due to the hindering effect of the impeller, correspondingly kinetic energy converted to pressure energy. The maximum value of the dynamic pressure, static pressure and total pressure in the blade runner were respectively 36.6kPa、28.9kPa、60.4kPa, while the minimum were respectively 3.0kPa、-35.3kPa、-31.2kPa. The maximum speed of the fluid in the impeller region was 8.56m/s, which was close to the rotational speed of the impeller 8.9m/s. Through the analysis of the fluid stream line in the flotation cell, it was found that the flow state was "W"-shaped three-dimensional of periodical movement. The lower part was vertical eddy movement while the upper flow was steady, which is consistent with the flotation process requirements. After the flow got through the stator, the flow was evenly distributed along the horizontal section the due to the orientation of the eddy plate flow board, there was no dead zone, indicating the structure of flotation machine is reasonable. Through the analysis of turbulence characteristic parameters, it was found that turbulent kinetic energy, turbulence intensity, turbulence dissipation rate distribute symmetry to the impeller center; The stirring region of the XJM-S8 flotation machine lied below 0.7m in the lower part of the regional body, while above 0.7m or more, it was the flotation separation region which was relatively stable. The turbulent intensity of the stirring region was six times than that of the flotation separation region. Turbulence intensity is proportional to the speed of the speed of the impeller. The constant rotational speed of the impeller is a similar criterion to the simulation of enlarged movement of XJM-S-type flotation machine to ensure similar turbulence intensity. Through numerical simulation of flow field analysis, characteristics of the flow field of XJM-S-type flotation cell can be deeply understood so that a certain theoretical foundation of the research and optimized design of flotation cell has been laid.更多还原