脉冲气流流场温度场数值模拟
发布时间：2018-08-04 18:08
【摘要】：脉冲气流干燥机内空气的流动状态对其内部物料干燥有重大影响。本研究运用商用软件Fluent模拟脉冲气流干燥机内的流场和温度场并进行分析,为深入理解脉冲气流干燥机理和干燥机改进设计提供理论指导。本研究以脉冲气流干燥机为对象,以计算流体力学(CFD)为理论基础,以Navier-Stokes方程作为控制方程组,采用标准k-ε湍流模型,运用Fluent软件对脉冲气流干燥机内的流场和温度场进行三维稳态模拟,研究结果如下：在直管情况下对气流干燥进行模拟时,入口速度越大干燥的效果越不好,这是因为在直管情况下物料达到温度平衡基本都处于管路的后半段,而入口速度的增大会使物料在干燥段内的时间减少,导致能量损失的同时不能保证物料干燥达到合格。对脉冲气流干燥机的干燥段流场进行数值模拟。在考虑重力的情况下,得到干燥段内部流场的速度、压力、颗粒运动轨迹等,并对这些数据进行了分析与比较。通过数值模拟得出：脉冲管路的主要作用是提高物料和空气的相对速度,相对速度差异越大,物料弥散在热介质中的表面积越大,使表面水分迅速蒸发。各个参数的的剧烈变化阶段大部分集中在管路的入口处到和上升段弯管连接的脉冲管路之间,即粒子在经过转弯段的上半段的时候,干燥就已经基本完成,这说明脉冲管路对物料的干燥具有良好的促进作用,但增加脉冲管路必然会加大能量的损耗,所以在考虑到干燥效率的同时必须考虑能量损耗。
[Abstract]:The flow state of the air in the pulse air dryer has a great influence on the material drying. In this study, the flow field and temperature field in the pulse airflow dryer were simulated and analyzed by using commercial software Fluent, which provided theoretical guidance for further understanding the mechanism of pulse airflow drying and improving the design of the dryer. In this study, the pulse airflow dryer was used as the object, the computational fluid dynamics (CFD) was taken as the theoretical basis, the Navier-Stokes equation was taken as the governing equations, and the standard k- 蔚 turbulence model was adopted. Three-dimensional steady state simulation of the flow field and temperature field in the pulse airflow dryer is carried out by using Fluent software. The results are as follows: when the airflow drying is simulated under the condition of straight pipe, the larger the inlet velocity is, the worse the drying effect is. This is because in the case of straight tube, the material temperature balance is basically in the second half of the pipeline, and the increase of inlet speed will reduce the time of material in the drying section, which leads to energy loss and can not guarantee the material drying to be up to standard. The numerical simulation of the flow field in the drying section of the pulse airflow dryer is carried out. Considering gravity, the velocity, pressure and particle trajectory of the flow field in the dry section are obtained, and these data are analyzed and compared. The numerical simulation shows that the main function of pulse pipeline is to increase the relative velocity of material and air. The greater the difference of relative velocity, the larger the surface area of material dispersion in hot medium, which makes the surface moisture evaporate rapidly. Most of the dramatic changes in the parameters are between the entrance of the pipe and the pulse pipe connected by the bend in the rising section, that is, by the time the particle passes through the upper half of the turning section, the drying is basically complete. This shows that the pulse pipeline has a good effect on the drying of materials, but increasing the pulse pipeline will inevitably increase the energy loss, so we must consider the energy loss while considering the drying efficiency.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB4
本文编号：2164684
[Abstract]:The flow state of the air in the pulse air dryer has a great influence on the material drying. In this study, the flow field and temperature field in the pulse airflow dryer were simulated and analyzed by using commercial software Fluent, which provided theoretical guidance for further understanding the mechanism of pulse airflow drying and improving the design of the dryer. In this study, the pulse airflow dryer was used as the object, the computational fluid dynamics (CFD) was taken as the theoretical basis, the Navier-Stokes equation was taken as the governing equations, and the standard k- 蔚 turbulence model was adopted. Three-dimensional steady state simulation of the flow field and temperature field in the pulse airflow dryer is carried out by using Fluent software. The results are as follows: when the airflow drying is simulated under the condition of straight pipe, the larger the inlet velocity is, the worse the drying effect is. This is because in the case of straight tube, the material temperature balance is basically in the second half of the pipeline, and the increase of inlet speed will reduce the time of material in the drying section, which leads to energy loss and can not guarantee the material drying to be up to standard. The numerical simulation of the flow field in the drying section of the pulse airflow dryer is carried out. Considering gravity, the velocity, pressure and particle trajectory of the flow field in the dry section are obtained, and these data are analyzed and compared. The numerical simulation shows that the main function of pulse pipeline is to increase the relative velocity of material and air. The greater the difference of relative velocity, the larger the surface area of material dispersion in hot medium, which makes the surface moisture evaporate rapidly. Most of the dramatic changes in the parameters are between the entrance of the pipe and the pulse pipe connected by the bend in the rising section, that is, by the time the particle passes through the upper half of the turning section, the drying is basically complete. This shows that the pulse pipeline has a good effect on the drying of materials, but increasing the pulse pipeline will inevitably increase the energy loss, so we must consider the energy loss while considering the drying efficiency.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB4
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