旋转半径和溶液入口条件对KDP晶体生长过程影响的数值模拟研究

发布时间：2018-04-05 08:15

本文选题：KDP晶体　切入点：数值模拟　出处：《重庆大学》2016年硕士论文

【摘要】：本文首先针对KDP晶体传统同心旋转的方式,对采用降温法时不同旋转半径下KDP晶体的生长过程进行数值模拟,着重分析旋转半径对晶体表面过饱和度大小及分布的影响,并研究其作用机理。同时通过改变晶体的摆放方式,进一步寻找提高晶体表面过饱和度和改善晶体表面均匀性的方法。其次,考虑到实际工业生产中以循环流动法生长晶体为主,为了便于对其生产过程进行理论指导,本文在不同旋转半径对晶体生长影响研究的基础上,对利用循环流动法生长晶体时,不同进口条件下KDP晶体的生长过程进行数值模拟,探寻不同进口条件对晶体生长过程中表面过饱和度大小及其分布影响的规律性,从而为更好的工业化生产KDP晶体奠定理论基础。本课题的主要研究内容和结论如下:(1)针对传统同心旋转法生长晶体的弊端,对采用降温法时不同旋转半径下KDP晶体的生长过程进行数值模拟。结果表明:随着旋转半径从0cm逐渐增加到3cm,晶体柱面和锥面时均过饱和度均逐渐增大,柱面过饱和度均方差逐渐减小,锥面过饱和度均方差先增大后减小。通过分析发现随着旋转半径的提高,溶液强制对流逐渐增强,溶质边界层逐渐变薄。说明增大晶体的旋转半径既可以提高晶体的生长速率,同时还可以改善晶体表面的均匀性。另外,在此基础上对旋转半径为3cm时,晶体表面过饱和度随时间的变化情况进行了分析。(2)在旋转半径一定的基础上,对采用降温法时不同晶体摆放方式下KDP晶体的生长过程进行数值模拟。结果表明:在柱面迎流、棱边迎流和锥面迎流三种不同的摆放方式下,当晶体采用柱面迎流时晶体时均表面过饱和度最大,棱边迎流时次之,采用锥面迎流时晶体时均表面过饱和度最小,且当晶体采用锥面迎流时晶体柱面和锥面均方差最大,采用柱面迎流时次之,采用棱边迎流时晶体柱面和锥面均方差最小。因此,虽然晶体采用棱边迎流的摆放方式时,时均表面过饱和度与柱面迎流相比略有下降,但其平均均方差是三种摆放方式中最小的,有利于减少包裹体的产生。(3)结合实际工业生产,将循环流动法与有旋转半径的转晶法相结合,对不同入口条件下KDP晶体生长过程中的溶液流动和物质输运过程进行了数值模拟研究,分别讨论了溶液入口速度、溶液进口管位置和溶液入射角度对晶体生长过程的影响。研究结果表明:首先,随着溶液入口速度的增大,晶体柱面时均过饱和度先减小后增大,晶体锥面时均过饱和度先略微减小后逐渐增大,柱面和锥面均方差均先增大后减小。其次,晶体表面过饱和度和均方差随着溶液进口管在生长槽上的位置不同而不同。当溶液进口管轴线与晶体中心在同一高度时,晶体表面过饱和度较大且均方差较小。最后,当溶液进口管轴线与晶体中心在同一高度时,随着溶液入射角相对晶体位置的不断增大,晶体柱面过饱和度先增大后减小,均方差先减小后增大,晶体锥面过饱和度先增大后减小继而又增大,锥面均方差则与锥面过饱和度呈现相反的规律。当入口管轴线与晶体旋转半径较小的锥尖运动轨迹相切时,晶体表面过饱和度最大,均方差最小。
[Abstract]:In this paper, the traditional KDP crystal concentric rotation mode, numerical simulation of the KDP crystal growth process under different rotation radius of cooling method, emphatically analyzes the influence of rotary radius on the surface supersaturation and size distribution, and study its mechanism. At the same time by changing the crystal display mode, further to improve the crystal surface. Method of saturation and improve the uniformity of the crystal surface. Secondly, considering the actual industrial production by circulating method of crystal growth, in order to facilitate the production process theory, this paper based on the study on the influence of different radius of crystal growth, the crystal growth by circulating method, numerical simulation of growth the process of KDP crystal under different inlet conditions, explore different inlet conditions on the crystal growth process of surface supersaturation and size distribution. Regular rings, which provides a theoretical basis for better industrial production of KDP crystal. The main research contents and conclusions are as follows: (1) aiming at the disadvantages of traditional concentric rotating crystal, the cooling method of numerical simulation of KDP crystal growth under different rotation radius of Guo Chengjin. The results show that with the radius of rotation increased from 0cm to 3cm, the crystal cylinder and cone are supersaturation increased, cylindrical supersaturation variance decreases, the cone supersaturation variance increases first and then decreases. The analysis found that as the rotation radius of forced solution convection increases, solute boundary layer becomes thinner. The rotation radius increases the crystal can improve the crystal growth rate, but also can improve the uniformity of the crystal surface. In addition, on the basis of the rotation radius is 3cm, the crystal surface supersaturation Changes with time are analyzed. (2) based on the rotation radius, the cooling method of different crystal growth process of KDP crystal display mode was simulated. The results show that the flow in the cylinder, edge flow and cone attack three different display mode, when the crystal the cylindrical upstream crystal are surface supersaturation, edge flow when the flow when using cone crystal surface supersaturation were minimal, and when the crystal with cone flow when the crystal cylinder and cone are the maximum variance, using cylindrical flow time, the flow at the edge crystal cylinder and cone are the smallest variance. Therefore, although the crystal edge flow display, when the surface supersaturation and cylindrical flow phase decreased slightly, but the average variance is the smallest of the three kinds of layout, reduces the package The body is produced. (3) according to the actual production, the circulating method combined with the rotation radius of the rotating crystal method, the solution of KDP crystal with different entrance conditions during the growth of flow and mass transport process were studied by numerical simulation, the solution of entrance velocity are discussed, the position and effect of solution inlet pipe the solution of incident angle on the process of crystal growth. The results show that: firstly, with the increase of solution entrance velocity, the crystal when the supersaturation decreases first and then increases, when the supersaturation of crystal cone first slightly increased gradually after, the cylinder and cone variance were first increased and then decreased. Secondly, the surface supersaturation and the mean variance with different solution inlet pipe in slot position and different growth. When the solution inlet tube axis and the center of the crystal at the same height, the surface supersaturation is larger and smaller mean square deviation. Later, when the solution inlet tube axis and the center of the crystal at the same height, angle of incidence relative to the crystal position as the solution increases, the crystal supersaturation increases first and then decreases, the variance decreases first and then increases, the crystal cone supersaturation increases first and then decreases and then increases, and the variance of cone cone supersaturation show instead of the law. When the tip trajectory tangent entrance pipe axis and smaller crystal rotation radius, the surface supersaturation maximum, minimum mean square error.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O78

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