考虑温度影响的气膜阻尼结构抑振率分析

Analysis of Vibration Suppression Rate of Air-Film Damping Structures Considering Temperature Effect

气膜阻尼能够有效抑制航空发动机叶片的多阶振动,且具有结构简单、附加质量小等优点。针对带气膜阻尼平板结构,建立了带气膜阻尼平板振动模型,推导出考虑温度影响的抑振率表达式;采用有限元法,研究了均匀温度场和非均匀温度场对气膜阻尼结构抑振率的影响。结果表明:①无论是在均匀温度场还是非均匀温度场下,带气膜阻尼平板均表现出较高的抑振率;在两种温度场下,平板温度由20℃增加至600℃,带气膜阻尼平板抑振率增幅均不超过10%。②气膜内气体温度由室温20℃增加到600℃时,带气膜阻尼平板抑振率增幅变化不超过4%,气膜内气体随温度变化对带气膜阻尼平板抑振率影响较小,可适用于不同温度环境。③当平板振动为二扭振型时,气膜阻尼结构抑振效果不仅大幅下降,而且吸振薄板的振动会加剧平板本身的振动,且在不同温度梯度下都可能出现。

Gas film damping can effectively suppress multi stage vibration of aeroengine blades which has the advantages of simple structure and small added mass. This paper focuses on the flat plate structure with gas film damping, establishes the vibration model of a flat plate with gas film damping, derives the expression of vibration suppression rate under the influence of the temperature;Using the finite element method, study the effects on the vibration suppression rate of gas film damping structures under uniform and non-uniform temperature fields. The results is:①Flat plates with air film damping have a high vibration suppression rates under uniform and non-uniform temperature fields;Under this two temperature fields, when the temperature field of the flat plate increases from 20℃ to 600℃, the increase in vibration suppression rate of gas film damping structure is less than 10%;②When the gas temperature inside the gas film increases from 20℃ to 600℃, the increase in vibration suppression rate of gas film damping structure is less than 4%, the variation of gas temperature in the gas film has less effect on the vibration suppression rate of a flat plate with gas film damping, can suitable for the different temperature environments;③When the vibration of the flat plate is in the second torsional vibration mode, the vibration suppression effect of the gas film damping structure decreases sharply, the vibration of the absorbing sheet will intensify the vibration of the flat plate, the phenomenon may occur under different temperature gradient.