柔性飞艇主气囊湿模态分析及试验研究

Wet Modal Analysis and Experiment Research on Flexible Airship Main Airbag

大型柔性飞艇是临近空间“长驻空”重要平台,具有重要的国防及民用价值,是近年来浮空器结构工程领域研究的热点之一。主气囊是柔性飞艇核心结构部件,为了研究大型柔性飞艇主气囊周边流场对其模态性能的影响,将柔性飞艇主气囊内、外气体视为不可压缩流体,将空气随囊体振动的影响作为附加质量添加到囊体结构中,采用基于势流理论的附加质量计算方法完成主气囊在5种不同内压下的干、湿模态分析;通过模态试验测得该主气囊内压在2、4、6、8和10 kPa下的前三阶振型及频率。结果表明:干、湿模态的前3阶频率均随内压的增加而增大;同种内压下,计入囊体周围空气的附加质量后,主气囊的湿模态频率降低。

Large flexible airship is an important platform for“long stay in the air”in near space.It is of important na⁃tional defense and civil value.It is one of the hotspots in the field of structural engineering of aerostat in recent years.The main airbag is the core structural component of the flexible airship.In order to study the influence of the flow field around the main airbag of the large flexible airship on its modal performance,the air around the main air⁃bag of the flexible airship is assumed as incompressible fluid,adding the influence of air vibrating with the airbag as an additional mass to the capsule structure.The dry and wet modal analysis of the main airbag under 5 different in⁃ternal pressures is completed by the additional mass calculation method based on the potential flow theory.The first three order of vibration modes and frequencies of the internal pressure of the main airbag at 2、4、6、8 and 10 kPa is obtained by experiment.The test and analysis results show that:the first 3 order of vibration frequencies of dry and wet mode gradually increase with the increase of internal pressure,under the same internal pressure,the wet modal frequency of the main airbag reduced when considering the influence of the air surrounding the airbag body with the structural vibration.