旋风分离器内置涡核破碎翼的实验及数值研究
发布时间：2018-11-08 21:16
【摘要】：旋风分离器作为典型的气固分离设备,工作机理主要依赖气流与其携带的尘粒之间存在密度差,导致两者一旦进入旋风分离器,作螺旋向下运动的同时,形成能使颗粒脱离气流主体运动从而被分离的速度滑移。早期的旋风分离器仅在工业领域应用比较广泛；而今随着旋风分离器逐年发展,该设备的性能不断得到优化,加之造价、运行成本低廉、可操作环境范围广,愈发得到全世界各个行业的重视。目前,微型旋风分离也被逐渐推广至空气净化、食品分离、生物、医药等精密行业。为更进一步优化旋风分离器的性能,人们对该设备的认知能力从简单的性能定性分析发展到流场特性的定量分析。然而,旋风分离器内相流变化规律反常,很多学者在对各种旋风分离器模型进行优化以获得较高效率的同时,不得不考虑压降增大的负面影响。本课题针对旋风分离器效率中等、压降较高的特点,试图改善旋风分离器性能使其向“保效减阻”的终极目标进发,提出一种能使旋风分离器压降损失大幅降低的新型置件——减阻叶片。课题在阅读大量前人研发成果,对旋风分离器进行深入了解的基础上,利用计算流体动力学方法(CFD),对传统Lapple型旋风分离器加设减阻装置前后的内部流场特征进行仿真模拟,主要分析了流场的三维速度、压强、旋度、湍流等性能参数的空间分布。首先,课题进行物理模型的建立,包括确定分离器各个组成部分的几何尺寸、模型绘制、网格划分与生成等。选择合理的数值模拟计算理论模型,设定初始条件；并通过利用前人实验研究结果,验证上述所选模型、操作参数。其次,基于实验室研究结果,本课题提出新型减阻装置,并针对不同模型进行数值模拟。实验室操作对象是传统Lapple型旋风分离器及加入五组不同长度叶片后的分离器,目的在于得到两种装置主要性能指标的实际值——收集效率(n)及压降。数值模拟选用雷诺应力模型(RSM),通过统计计算结果,得到气相流场特征,如压力场分布、湍流结构等；初步分析减阻叶片长度对旋风分离器性能产生不同影响的机理。以单相流流场为前提,利用基于欧拉—拉格朗日方法的离散化模型(DPM)模拟不同粒径颗粒在分离器内的运动及分布。对传统模型与L=I00mm分离器中单个颗粒的受力情况进行计算并比较,同时模拟计算典型设备中作用在不同粒径颗粒上离心力与径向曳力的合力(Fc+Fr),阐明颗粒的最终走向。最后,为得到获得减阻装置优化设计,验证分离器内产生压降损耗的主要区域,考察大量过程变量：以长度为100mm的叶片为基础,考察减阻叶片参数(疏密、宽度、组数等)变化对分离器性能的影响,分析减阻机理；同时提出改变溢流管结构及在溢流管附近区域安装制件得到新型分离模型,分析其与传统Lapple型分离器性能及流场分布差异,得到分离器优化设计。
[Abstract]:As a typical gas-solid separation equipment, the working mechanism of the cyclone separator mainly depends on the density difference between the air flow and the dust particles it carries, which leads to the spiral downward movement of both the cyclone separator and the cyclone separator once they enter the cyclone separator. A velocity slip is formed to separate particles from the movement of the main body of the airflow. The early cyclone separator was only widely used in the industrial field. With the development of cyclone separator year by year, the performance of the equipment has been continuously optimized, in addition to the cost, low operating costs, a wide range of operational environment, more and more attention has been paid to the various industries around the world. At present, micro cyclone separation has been gradually extended to air purification, food separation, biology, medicine and other precision industries. In order to further optimize the performance of the cyclone separator, the cognitive ability of the device has been developed from simple qualitative analysis to quantitative analysis of the flow field characteristics. However, the variation law of phase flow in cyclone separator is abnormal. Many scholars have to consider the negative effect of increasing pressure drop while optimizing various cyclone separator models to obtain higher efficiency. Aiming at the characteristics of the cyclone separator with medium efficiency and high pressure drop, this paper tries to improve the performance of the cyclone separator so that it can advance towards the ultimate goal of "ensuring efficiency and reducing drag". A new type of device, drag reducing blade, which can greatly reduce the pressure drop loss of cyclone separator, is presented. On the basis of reading a large number of previous research and development achievements and deeply understanding the cyclone separator, the subject uses the computational fluid dynamics (CFD),) method. The internal flow field characteristics of the traditional Lapple cyclone separator before and after the installation of drag reduction device are simulated. The spatial distribution of three dimensional velocity, pressure, curl, turbulence and other performance parameters of the flow field is mainly analyzed. Firstly, the physical model is built, including the geometric dimension of each component of the separator, model drawing, mesh generation and so on. A reasonable theoretical model of numerical simulation is selected to set the initial conditions, and the operation parameters are verified by using the results of previous experiments. Secondly, based on the results of laboratory research, a new type of drag reduction device is proposed, and numerical simulation is carried out for different models. The object of laboratory operation is the traditional Lapple cyclone separator and the separator after adding five groups of blades of different lengths. The purpose of the experiment is to obtain the actual values of the main performance indexes of the two kinds of equipment, namely, the collection efficiency (n) and the pressure drop. The Reynolds stress model (RSM),) is used for numerical simulation to obtain the characteristics of gas phase flow field, such as pressure field distribution and turbulent structure, and the mechanism of different influence of drag reducing blade length on the performance of cyclone separator is preliminarily analyzed. On the premise of single-phase flow field, the discrete model (DPM) based on Euler-Lagrangian method is used to simulate the movement and distribution of particles with different particle sizes in the separator. The forces acting on a single particle in the traditional model and the L=I00mm separator are calculated and compared. At the same time, the combined forces of centrifugal force and radial drag acting on different particle sizes in typical equipment are simulated and calculated to illustrate the final direction of the particles. Finally, in order to obtain the optimal design of drag reduction device and verify the main area of pressure drop loss in the separator, a large number of process variables are investigated: based on the blade with length of 100mm, the parameters of drag reducing blade (density, width, width) are investigated. The effect of the number of components on the performance of the separator and the mechanism of drag reduction are analyzed. At the same time, a new separation model is proposed by changing the structure of the overflow pipe and installing the components near the overflow pipe. The performance and flow field distribution difference between the new model and the traditional Lapple separator is analyzed, and the optimum design of the separator is obtained.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.8
本文编号：2319707
[Abstract]:As a typical gas-solid separation equipment, the working mechanism of the cyclone separator mainly depends on the density difference between the air flow and the dust particles it carries, which leads to the spiral downward movement of both the cyclone separator and the cyclone separator once they enter the cyclone separator. A velocity slip is formed to separate particles from the movement of the main body of the airflow. The early cyclone separator was only widely used in the industrial field. With the development of cyclone separator year by year, the performance of the equipment has been continuously optimized, in addition to the cost, low operating costs, a wide range of operational environment, more and more attention has been paid to the various industries around the world. At present, micro cyclone separation has been gradually extended to air purification, food separation, biology, medicine and other precision industries. In order to further optimize the performance of the cyclone separator, the cognitive ability of the device has been developed from simple qualitative analysis to quantitative analysis of the flow field characteristics. However, the variation law of phase flow in cyclone separator is abnormal. Many scholars have to consider the negative effect of increasing pressure drop while optimizing various cyclone separator models to obtain higher efficiency. Aiming at the characteristics of the cyclone separator with medium efficiency and high pressure drop, this paper tries to improve the performance of the cyclone separator so that it can advance towards the ultimate goal of "ensuring efficiency and reducing drag". A new type of device, drag reducing blade, which can greatly reduce the pressure drop loss of cyclone separator, is presented. On the basis of reading a large number of previous research and development achievements and deeply understanding the cyclone separator, the subject uses the computational fluid dynamics (CFD),) method. The internal flow field characteristics of the traditional Lapple cyclone separator before and after the installation of drag reduction device are simulated. The spatial distribution of three dimensional velocity, pressure, curl, turbulence and other performance parameters of the flow field is mainly analyzed. Firstly, the physical model is built, including the geometric dimension of each component of the separator, model drawing, mesh generation and so on. A reasonable theoretical model of numerical simulation is selected to set the initial conditions, and the operation parameters are verified by using the results of previous experiments. Secondly, based on the results of laboratory research, a new type of drag reduction device is proposed, and numerical simulation is carried out for different models. The object of laboratory operation is the traditional Lapple cyclone separator and the separator after adding five groups of blades of different lengths. The purpose of the experiment is to obtain the actual values of the main performance indexes of the two kinds of equipment, namely, the collection efficiency (n) and the pressure drop. The Reynolds stress model (RSM),) is used for numerical simulation to obtain the characteristics of gas phase flow field, such as pressure field distribution and turbulent structure, and the mechanism of different influence of drag reducing blade length on the performance of cyclone separator is preliminarily analyzed. On the premise of single-phase flow field, the discrete model (DPM) based on Euler-Lagrangian method is used to simulate the movement and distribution of particles with different particle sizes in the separator. The forces acting on a single particle in the traditional model and the L=I00mm separator are calculated and compared. At the same time, the combined forces of centrifugal force and radial drag acting on different particle sizes in typical equipment are simulated and calculated to illustrate the final direction of the particles. Finally, in order to obtain the optimal design of drag reduction device and verify the main area of pressure drop loss in the separator, a large number of process variables are investigated: based on the blade with length of 100mm, the parameters of drag reducing blade (density, width, width) are investigated. The effect of the number of components on the performance of the separator and the mechanism of drag reduction are analyzed. At the same time, a new separation model is proposed by changing the structure of the overflow pipe and installing the components near the overflow pipe. The performance and flow field distribution difference between the new model and the traditional Lapple separator is analyzed, and the optimum design of the separator is obtained.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.8
【参考文献】
相关期刊论文 前1条
1 林玮,王乃宁;旋风分离器内三维两相流场的数值模拟[J];动力工程;1999年01期
，本文编号：2319707
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