炉内管道气体绕流及气动噪声特性研究

发布时间：2018-06-12 16:22

本文选题：管道气动噪声 + 计算气动声学　；参考：《华北电力大学》2017年硕士论文

【摘要】：电能是国家重要的战略能源,对于国民经济影响深远,而锅炉泄漏导致的非计划停机严重影响了发电容量,因此对锅炉泄漏的监测和准确定位十分重要。在诸多监测泄漏手段中,声学监测方法潜力巨大、优势十分突出,声学监测技术在国内外电厂都得到了广泛的应用,然而由于声学理论基础和对炉内声学特性的研究不够完善,声学诊断技术仍然存在许多问题。当炉内管道发生泄漏时,泄漏喷流冲击附近的管道形成次级声源,由于次级声源的干扰,使得声学诊断和定位准确性大大降低,为了使得炉内声学检测定位更加精确和具有时效性,对次级声源的研究刻不容缓。为了深入探究炉内管道气体绕流及气动噪声的特性,本文采用计算气动声学(CAA)方法,利用流体力学仿真软件FLUENT,选用大涡模拟方法建立模型,对泄漏喷流在运动过程中冲击管道所形成的一系列流场及声场特性进行了研究,分析了单管道绕流风吹声的流场及声辐射特性,多管道绕流所形成的管道耦合效应,以及管道绕流风吹声的声源机制和声辐射效应。为了验证数值模拟方法的准确性和可行性,在常温常压下进行实验,与数值模拟结果吻合度较好。通过对结果的分析,得到的主要结论有:流场特性可以很好的解释炉内管道绕流气动噪声的声辐射特性。单管道的管道绕流声场的声辐射指向性与声偶极子的辐射特性相似。来流速度越大,管道间的耦合效应越强。来流角度和管道间距以及管道单元结构对于管道的流场和声辐射效应影响很大,主要结论有:增大管道间距,管道间的耦合效应降低;改变来流角度,在垂直于来流面的方向上容易出现动压及声压级的极大值;三管道的相对排列位置不同,上游管道后方脱落的漩涡撞击下游管道后对动压及声压级的增强效果不同。
[Abstract]:Electric energy is an important national strategic energy, which has far-reaching influence on the national economy. The unplanned shutdown caused by boiler leakage seriously affects the power generation capacity, so it is very important to monitor and locate boiler leakage accurately. Among the many leakage monitoring methods, acoustic monitoring methods have great potential and outstanding advantages. Acoustic monitoring technology has been widely used in power plants at home and abroad. However, due to the sound theory foundation and the study of acoustic characteristics in the furnace is not perfect. There are still many problems in acoustic diagnostic technology. When the pipeline in the furnace leaks, the leakage jet impinges on the nearby pipeline to form the secondary sound source. Because of the interference of the secondary sound source, the accuracy of acoustic diagnosis and location is greatly reduced. In order to make the localization of acoustic detection in furnace more accurate and timely, it is urgent to study secondary sound sources. In order to deeply investigate the characteristics of gas flow and aerodynamic noise in the furnace, this paper adopts the method of computational aero acoustics (CAA), uses fluid dynamics simulation software fluent, and chooses the method of large eddy simulation to establish the model. The characteristics of a series of flow field and sound field formed by the impingement of the leakage jet in the moving process are studied. The characteristics of the flow field and sound radiation of the wind blowing around the single pipe and the coupling effect of the multi-pipe flow around the pipe are analyzed. And the sound source mechanism and sound radiation effect of the wind blowing around the pipeline. In order to verify the accuracy and feasibility of the numerical simulation method, experiments were carried out at room temperature and atmospheric pressure, and the results were in good agreement with the numerical simulation results. Through the analysis of the results, the main conclusions are as follows: the characteristics of the flow field can well explain the acoustic radiation characteristics of the aerodynamic noise around the pipe in the furnace. The acoustic radiation directivity of the sound field around the pipe is similar to that of the acoustic dipole. The greater the speed of the incoming flow, the stronger the coupling effect between the pipes. The flow field and acoustic radiation effect are greatly affected by the flow angle and the spacing of the pipeline and the structure of the pipeline unit. The main conclusions are as follows: the coupling effect between the pipes decreases with the increase of the distance between the pipes, and the flow angle is changed. The maximum of dynamic pressure and sound pressure level is easy to appear in the direction perpendicular to the incoming flow surface, and the relative arrangement of the three pipelines is different, and the enhancement effect of the vortex falling off from the back of the upstream pipeline to the downstream pipeline is different.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O357.5;TM621.2

【参考文献】