液气射流泵性能研究与数值模拟

发布时间：2018-06-10 05:01

本文选题：射流泵 + 单一变量法　；参考：《西南石油大学》2017年硕士论文

【摘要】：射流泵是一种利用高速射流作为动力来传递动能和质量的流体机械和混合反应设备,其本身没有运动部件,具有结构简单、安装方便、工作可靠、寿命长等优点,在许多工艺流程中应用具有优越性和不可替代性,在国民经济的发展中起着重要的作用。但射流泵的缺点是由于工作流体(射流)和被吸流体(引射流体)混合能量损失很大,导致泵的效率较低,这在一定程度限制了射流泵的应用范围。本文利用有限元软件FLUENT17.0对液气射流泵内部流场进行模拟,研究喉嘴距、面积比、喷嘴结构和喷嘴安装形式等结构形式和不同工况对射流泵流场分布规律的影响,寻求射流泵效率较高时的结构参数和合理工况。主要开展以下工作:以单一变量法为基础,构建不同喉嘴距和面积比下液气射流泵流体域模型,导入到ICEM-CFD中进行网格划分并设定射流泵的各种边界,选择Mixture多相流模型和标准k-ε湍流模型来进行数值模拟。利用CFD-Post提取泵内压力和速度分布云图,提取进出口压力和质量流量数据。对不同结构尺寸(面积比、喉嘴距)液气射流泵的流场性能进行比较分析,以效率较优为目标,得到较优喉嘴距和面积比。在较优喉嘴距和面积比下,将余弦、圆锥和圆柱喷嘴的性能进行对比,得出圆柱喷嘴射流泵的壁面压力变化和轴线上的压力变化较余弦、圆锥喷嘴射流泵更大,由于工作流体经过其收缩断面,能量损失较大,效率相对余弦、圆锥喷嘴低。余弦和圆锥喷嘴射流泵流场特性相近,考虑到余弦喷嘴不易加工,射流泵采用圆锥喷嘴更合理。在较优喉嘴距和面积比下,考察多喷嘴液气射流泵内部流场特性,设计了圆形三喷嘴、三角形三喷嘴、环向四喷嘴、中心四喷嘴和六喷嘴这五种多喷嘴射流泵,并使多喷嘴的喷嘴出口总面积等于单喷嘴且在同样边界条件下模拟。本次设计的多喷嘴效率整体低于单喷嘴,说明多喷嘴不总是可以提高泵的效率,喷嘴自身的结构和布置形式会影响泵的效率。对比研究了平行六喷嘴和2种倾斜角度不同的聚焦六喷嘴射流泵的效率,得出聚焦多喷嘴可以提高泵的效率,喷嘴倾斜角越大,越有利于射流进行交汇,形成的高速流核区向前推进的距离越大,越有利于水射流与气体混合,提高泵的效率。研究不同工况下射流泵的性能,依次改变工作流体压力和混合流体出口压力,寻求合理的工况。得出过高或过低工作流体压力会降低泵的效率;适当减小混合流体出口压力能提高射流泵的效率,但出口压力过大会降低泵的效率。所以需要严格控制泵的进口压力和出口压力,才正常保证泵正常乃至高效运行。总之,本文通过对液气射流泵内部流场进行数值模拟,对比研究喉嘴距、面积比、喷嘴形状、喷嘴个数喷嘴、布置形式和不同工况(不同工作流体压力和混合流体出口压力)流场分布规律,可为射流泵选择较优的结构参数和合理的运行工况,研究结论可为射流泵的设计提供一定理论依据。
[Abstract]:The jet pump is a kind of fluid machinery and mixed reaction equipment which uses high speed jet as power to transfer kinetic energy and mass. It has no moving parts in itself. It has the advantages of simple structure, easy installation, reliable work and long life. It has advantages and irreplaceable application in many process processes. It plays a role in the development of the national economy. But the shortcoming of the jet pump is that the loss of the mixing energy of the working fluid (jet) and the absorbed fluid (the ejected fluid) is very low, which leads to the low efficiency of the pump. This restricts the application range of the jet pump to a certain extent. This paper uses the finite element software FLUENT17.0 to simulate the internal flow field of the liquid gas jet pump, and study the throat distance and area. The structure parameters and reasonable working conditions of the jet pump are sought by the structure of the nozzle structure and the nozzle installation form and the different working conditions on the flow field distribution of the jet pump. The following work is carried out mainly: Based on the single variable method, the fluid field model of the liquid gas jet pump under the different throat and area ratio is constructed and introduced into the IC In EM-CFD, the grid is divided and the various boundaries of the jet pump are set, and the Mixture multiphase flow model and the standard k- e turbulence model are selected for numerical simulation. The pressure and velocity distribution in the pump are extracted by CFD-Post, and the pressure and mass flow data are extracted. The flow field of the liquid gas jet pump with different structure scale (area ratio, throat distance) The performance is compared and analyzed. The better throat and area ratio are obtained. Under the better throat and area ratio, the performance of the cosine, cone and cylindrical nozzle is compared, and the wall pressure change of the jet pump and the pressure on the axis are changed to the cosine, the jet pump of the cone nozzle is larger, because of the workflow. Through its contraction section, the energy loss is larger, the efficiency is relative cosine, the conical nozzle is low. The flow field characteristics of the cosine and conical nozzle are similar. Considering that the cosine nozzle is not easy to be machined, the jet pump is more reasonable with the cone nozzle. Under the better throat and area ratio, the flow field characteristics of the multi nozzle liquid gas jet pump are investigated and the circle is designed. Three nozzles, triangular three nozzles, ring four nozzles, center four nozzles and six nozzles are the five multi nozzle jet pumps. The total area of the nozzle outlet is equal to the single nozzle and is simulated under the same boundary conditions. The design of the multi nozzle efficiency is lower than the single nozzle. It is said that the nozzle is not always able to improve the efficiency of the pump. The structure and layout of the body will affect the efficiency of the pump. The efficiency of the parallel six nozzle and 2 different focus six nozzle jet pumps is compared and studied. It is concluded that the focus multiple nozzles can improve the efficiency of the pump. The greater the inclination angle of the nozzle, the more conducive to the convergence of the jet. It is beneficial to the mixing of water jet and gas to improve the efficiency of the pump. To study the performance of the jet pump under different working conditions, to change the pressure of the working fluid and the pressure of the mixed fluid outlet in turn, to find a reasonable working condition. It is concluded that the efficiency of the pump will be reduced by high or low working fluid pressure, and the efficiency of the jet pump can be improved by proper Jian Xiaohun fluid outlet pressure, but the efficiency of the jet pump can be improved. It is necessary to strictly control the inlet pressure and outlet pressure of the pump so as to ensure the normal and efficient operation of the pump. In a word, through the numerical simulation of the internal flow field of the liquid and gas jet pump, this paper compares the throat distance, the area ratio, the nozzle shape, the nozzle number nozzle, the layout form and the different work. The distribution of flow field (different working fluid pressure and mixed fluid outlet pressure) can choose better structural parameters and reasonable operating conditions for the jet pump, and the conclusion can provide a certain theoretical basis for the design of the jet pump.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH38

【参考文献】