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Unsteady 3-D RANS simulations of dust explosion in a fan stirred explosion vessel using an open source code
Journal of Loss Prevention in the Process Industries ( IF 3.5 ) Pub Date : 2020-07-24 , DOI: 10.1016/j.jlp.2020.104237
Chen Huang , Andrei N. Lipatnikov , Ken Nessvi

Dust explosion is a constant threat to industries which deal with combustible powders such as woodworking, metal processing, food and feed, pharmaceuticals and additive industries. The current standards regarding dust explosion venting protecting systems, such as EN 14491 (2012) and NFPA 68 (2018), are based on empirical correlations and neglect effects due to complex geometry. Such a simplification may lead to failure in estimating explosion overpressure, thus, increasing risk for injuries and even fatalities at workplaces. Therefore, there is a strong need for a numerical tool for designing explosion protecting systems. This work aims at contributing to the development of such a tool by (i) implementing a premixed turbulent combustion model into OpenFOAM, (ii) verifying the implementation using benchmark analytical solutions, and (iii) validating the numerical platform against experimental data on cornflour dust explosion in a fan-stirred explosion vessel, obtained by Bradley et al. (1989a) under well-controlled laboratory conditions.

For this purpose, the so-called Flame Speed Closure model of the influence of turbulence on premixed combustion is adapted and implemented into OpenFOAM. The implementation of the model is verified using exact and approximate analytical solutions for statistically one-dimensional planar and spherical turbulent flames, respectively. The developed numerical platform is applied to unsteady three-dimensional Reynolds Averaged Navier-Stokes simulations of the aforementioned experiments. The results show that the major trends, i.e. (i) a linear increase in an apparent turbulent flame speed St,b with an increase in the root mean square (rms) turbulent velocity u' and (ii) and an increase in St,b with an increase in the mean flame radius, are qualitatively predicted. Furthermore, the measured and computed dependencies of St,b(u') agree quantitatively under conditions of weak and moderate turbulence.



中文翻译:

使用开源代码对风机搅拌式爆炸容器中的粉尘爆炸进行非稳态3-D RANS模拟

粉尘爆炸对处理可燃粉的行业构成持续威胁,例如木工,金属加工,食品和饲料,制药和添加剂行业。当前关于粉尘爆炸防护系统的标准,例如EN 14491(2012)和NFPA 68(2018),是基于经验相关性和由于复杂几何形状而忽略的影响。这种简化可能导致无法估算爆炸超压,从而增加工作场所受伤甚至死亡的风险。因此,强烈需要一种用于设计防爆系统的数值工具。这项工作旨在通过(i)在OpenFOAM中实施预混的湍流燃烧模型,(ii)使用基准分析解决方案验证实施情况,从而为开发这种工具做出贡献。(iii)根据Bradley等人获得的扇形爆炸容器中的玉米粉尘爆炸实验数据验证数值平台。(1989a)在良好控制的实验室条件下。

为此,在OpenFOAM中采用了湍流对预混燃烧影响的所谓火焰速度闭合模型,并将其实现。使用分别针对统计一维平面和球形湍流火焰的精确和近似解析解验证了模型的实现。所开发的数值平台被应用于上述实验的非稳态三维雷诺平均纳维-斯托克斯模拟。结果表明,主要趋势,即(i)表观湍流火焰速度呈线性增加小号Ťb 随均方根(rms)湍流速度的增加 ü' 和(ii)以及 小号Ťb定性地预测了平均火焰半径的增加。此外,测量和计算的依存关系小号Ťbü' 在弱和中等湍流条件下定量地达成一致。

更新日期:2020-07-24
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