飞艇蒙皮振动对流场特性的影响

通过求解二维雷诺平均Navier-Stokes方程,采用SST两方程湍流模型对飞艇二维绕流流场进行数值模拟,重点分析飞艇蒙皮振动对流场的影响。为便于流场对比,在飞艇蒙皮的上表面给定一种沿流向传播的振动波型,通过调整振动的振幅、频率和波长,分析3种振动参数对流动分离和阻力的影响。研究结果表明:沿流向的蒙皮振动会使飞艇绕流流场产生显著变化。在一定振幅和频率条件下,随着波长的减小,流动分离加剧,阻力系数增加;在固定波长和频率条件下,随着振幅的增加,流动分离加剧,阻力系数增加;而在固定振幅和波长条件下,随着频率的增加,非定常效应增强,流动分离减弱,阻力系数减小;此外还发现,选取一定的振动形式和合适的参数可能起到抑制流动分离,从而减小阻力的作用,为高空飞艇减阻提供了一种技术途径。

The Influence of Airship Envelop Vibration on the Flow Field

By solving two-dimensional Reynolds-Averaged Navier-Stokes equation and using two equation SST turbulent models,the two dimensional flow field of an airship is simulated.The influence of airship envelop vibration on the flow field is analyzed.The influence on flow separation and drag of different vibration amplitude,frequency and wave length is analyzed on the hypothesis that a wave is promulgating in the flow direction on the airship envelop upper surface.The results indicate that the vibration can make the airship flow field dramatically change: with fixed vibration amplitude and frequency,reducing wave length will result in flow separation and drag coefficient increase;with fixed wave length and frequency,increasing amplitude will have the same effect;with fixed wave length and amplitude,increasing frequency will induce flow separation and drag coefficient decrease because of the enhancement of unsteady effect.Besides,it also demonstrates that certain form of vibration with suitable vibration correlation parameters may restrain flow separation and reduce drag,which would be an approach for decreasing drag of airship.