两相流喷嘴内外流场雾化特性的数值模拟及实验研究

发布时间：2019-01-04 23:38

【摘要】：在科技飞速发展的21世纪,喷雾的应用非常广泛,大到涉及工业生产、农业生产的方方面面,小到与人民息息相关的日常生活。在整个喷雾系统中喷嘴是最重要的原件,喷嘴结构特性的好坏对雾化特性起着决定性的影响,因此对于研究喷雾系统雾化特性,我们首先要研究喷嘴的雾化特性。生产生活中涉及到的雾化喷嘴构造都非常单一,但是喷射压力要求高且雾化效果差。两相流喷嘴在雾化领域中占有重要地位,其主要特征就是喷嘴内部既设计有液体流道又有气体流道。两相流气力式喷嘴雾化原理就是通过高压气体的高压喷射功能,在喷嘴出口处气体以较高的速度夹杂着液体喷出,利用两相之间的相互作用把液体雾化成微小的颗粒。本文分别采用数值模拟和实验研究的方法对内混式两相流喷嘴进行了雾化特性的研究。本文所完成的研究工作主要包括如下几点内容:1.理论分析及数值研究方面,首先,针对内外流场分别通过Solidworks软件进行了数值模型的建立。然后,在ICEM中进行网格划分及边界条件的设定。之后,在ANSYS Fluent中设定初始条件及计算控制参数等并进行数值计算,对计算结果进行后处理。最后,通过软件后处理功能把压力、速度等重要参数绘制成简单易懂的粒子图,便于分析喷嘴在不同工况下的两相流动特性。2.实验研究方面,首先在实验室有限条件下搭建了一套两相流动实验平台,设计了一套喷雾实验测试系统。然后,对喷雾系统进行测试以及实验工况的选定。之后,通过数码相机拍摄不同工况下的喷雾锥角、液滴速度及粒径成像图。最后,通过Photoshop软件对图像进行处理分析。得到了雾化锥角随流量、压力等物理量的变化规律以及一定流量不同压力下液滴速度及粒径的变化规律及均匀分布情况。本文把仿真模拟结果与实验结果进行比较,通过图形方式剖析两种方法的契合度,通过比较得到两种结果总体上比较切合,局部结果分歧较大,希望研究结论为以后喷雾的研发设计提供参考。
[Abstract]:In the 21st century, the rapid development of science and technology, spray is widely used, from industrial production, agricultural production aspects, small to people's daily life. The nozzle is the most important part in the whole spray system, and the structure of the nozzle plays a decisive role in the atomization characteristics. Therefore, we must first study the atomization characteristics of the spray system. The atomizing nozzle structure involved in production and life is very simple, but the spray pressure is high and the atomization effect is poor. Two-phase flow nozzles play an important role in the atomization field, the main characteristic of which is that there are both liquid and gas channels in the nozzle. The atomization principle of two-phase flow pneumatic nozzle is to atomize the liquid into tiny particles by using the interaction between the two phases through the high-pressure injection function of the high-pressure gas, the gas is ejected at a higher velocity at the nozzle outlet. In this paper, the atomization characteristics of two phase flow nozzles with internal mixing are studied by numerical simulation and experimental study. The research work accomplished in this paper mainly includes the following contents: 1. In theoretical analysis and numerical research, firstly, the numerical model of internal and external flow field is established by Solidworks software. Then, mesh generation and boundary condition setting are carried out in ICEM. After that, the initial conditions and control parameters are set in ANSYS Fluent and numerical calculation is carried out, and the calculation results are processed. Finally, the important parameters such as pressure, velocity and other important parameters are drawn into a simple and easy to understand particle diagram through the post-processing function of the software, which is convenient to analyze the two-phase flow characteristics of the nozzle under different working conditions. 2. In the aspect of experimental research, a set of two phase flow experimental platform was set up under the limited conditions of laboratory, and a set of spray experiment test system was designed. Then, the spray system was tested and the experimental conditions were selected. After that, the spray cone angle, droplet velocity and particle size were taken by digital camera. Finally, the image is processed and analyzed by Photoshop software. The variation law of atomization cone angle with flow rate, pressure and other physical quantities, as well as the variation law and uniform distribution of droplet velocity and particle size under different pressure of certain flow rate are obtained. In this paper, the simulation results are compared with the experimental results, and the degree of agreement between the two methods is analyzed by means of graphics. By comparing the two results, it is found that the two results are generally more suitable and the local results diverge greatly. It is hoped that the conclusion of the study will provide a reference for the future research and design of spray.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O359

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