上海交通大学 机械与动力工程学院， 上海 200240
发布日期:2020-03-06通讯作者:吴亚东，男，副研究员，博士生导师，电话（Tel.）：13564311521；E-mail: yadongwu@sjtu.edu.cn.作者简介:谢海润（1989-），男，河南省南阳市人，博士生，主要从事风扇叶片气动弹性特性研究.基金资助:上海市自然科学基金(18ZR1418600)，2011航空发动机协同中心资助项目Modal Analysis of Wake Induced Vibration Transient Process Based on POD and DMD
XIE Hairun,WU Yadong,OUYANG Hua,WANG AnzhengSchool of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published:2020-03-06摘要/Abstract
摘要： 尾涡激振是气动弹性领域的一种常见现象，在上游尾迹的气动激励下会导致流场中结构的强迫振动，该现象会危及被激励结构的完整性和疲劳寿命.本文使用圆柱/叶片的近似模型研究尾涡激振问题.该模型中的圆柱位于上游均匀来流，能够产生特定频率的卡门涡街；叶片位于流场下游，受到圆柱尾迹所施加的持续脉动激励，产生强迫振动.针对尾涡激励的近似模型，通过基于Fluent的二维数值计算，模拟了上游圆柱的脱落涡以及叶片从固定到以本身自然频率振动的瞬态过程，从而提供了流场变化过程的详细信息.基于非定常瞬态结果，采用本征正交分解(POD)和动态模态分解(DMD)分析方法，通过分解与重构叶片附近流场的压力场，提取模态频率及其变化过程，得到了尾涡激振现象的主要流动特征.通过对比两种模态分析结果发现，POD重构在残差处理方面有较大的优势，而DMD在单一频率模态的提取以及变化情况的分析方面更有优势.
关键词: 尾涡激振； 瞬态过程； 本征正交分解； 动态模态分解
Abstract: Wake induced vibration is a common phenomenon in the field of aeroelasticity which can cause forced vibrations of the structure. This phenomenon can endanger the integrity and the fatigue life of the excited structure. In this paper, wake induced vibration is studied by an approximate model with upstream cylinder and downstream blade. The cylinder in freestream produces Karman vortex street with a specific frequency. When the cylinder wake encounters the downstream blade, continuous pulse excitation is applied to the blade. Two-dimension numerical simulation based on Fluent illustrates the shedding vortex and transient process of blade from static to vibration at its natural frequency, and the detail information of transient flow field is obtained. Based on the unsteady transient results, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are applied for the decomposition and the reconstruction of the pressure field near the vibrating blade. The modal frequency and the evolution process are extracted to capture the main flow structure of wake induced vibration. The comparison of two modal analysis methods shows that POD reconstruction has a smaller maximum residual than DMD, and DMD has more advantages in single frequency mode extraction and corresponding evolution analysis.
Key words: wake induced vibration; transient process; proper orthogonal decomposition (POD); dynamic mode decomposition (DMD)
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