脈沖氣流流場溫度場數值模擬
發(fā)布時間：2018-08-04 18:08
【摘要】：脈沖氣流干燥機內空氣的流動狀態(tài)對其內部物料干燥有重大影響。本研究運用商用軟件Fluent模擬脈沖氣流干燥機內的流場和溫度場并進行分析,為深入理解脈沖氣流干燥機理和干燥機改進設計提供理論指導。本研究以脈沖氣流干燥機為對象,以計算流體力學(CFD)為理論基礎,以Navier-Stokes方程作為控制方程組,采用標準k-ε湍流模型,運用Fluent軟件對脈沖氣流干燥機內的流場和溫度場進行三維穩(wěn)態(tài)模擬,研究結果如下：在直管情況下對氣流干燥進行模擬時,入口速度越大干燥的效果越不好,這是因為在直管情況下物料達到溫度平衡基本都處于管路的后半段,而入口速度的增大會使物料在干燥段內的時間減少,導致能量損失的同時不能保證物料干燥達到合格。對脈沖氣流干燥機的干燥段流場進行數值模擬。在考慮重力的情況下,得到干燥段內部流場的速度、壓力、顆粒運動軌跡等,并對這些數據進行了分析與比較。通過數值模擬得出：脈沖管路的主要作用是提高物料和空氣的相對速度,相對速度差異越大,物料彌散在熱介質中的表面積越大,使表面水分迅速蒸發(fā)。各個參數的的劇烈變化階段大部分集中在管路的入口處到和上升段彎管連接的脈沖管路之間,即粒子在經過轉彎段的上半段的時候,干燥就已經基本完成,這說明脈沖管路對物料的干燥具有良好的促進作用,但增加脈沖管路必然會加大能量的損耗,所以在考慮到干燥效率的同時必須考慮能量損耗。
[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.
【學位授予單位】：東北大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB4
本文編號：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.
【學位授予單位】：東北大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB4
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