近地、水面时的飞行器动态稳定特性数值模拟

基于非结构动态网格重构技术,采用SA模型以及VOF方法,分别对NACA0012二维翼型自由空间、近地效应以及近水面效应的非定常运动流场进行了数值计算分析,并根据建立的基于小幅度强迫振动的组合动导数辨识方法计算了各个攻角下动导数。计算结果分析表明动导数计算方法准确可靠;中小攻角下,地面与水面以管道效应影响流场,均损失了动态阻尼,柔性的水面损失更多,动导数绝对值更小;大攻角时,两者表现为阻塞效应,柔性水面下的动态阻尼增大,动导数绝对值也变大;相比地面效应,柔性的水面影响范围更广。

Numerical simulation of aircraft dynamic stability characteristics flying over ground and water surface

Based on unstructured dynamic mesh technique, SA turbulence model and volume of fluid (VOF) method, the 2-dimensional airfoil (NACA0012) unsteady aerodynamics flying over free flow field, ground and water surface were numerically studied, also the method to identify dynamic stability derivative was de-veloped. It is shown that the method to calculate dynamic derivative is reliable. The absolute value of com-bined longitudinal dynamic derivative with water effect is the least at small angle of attack (AoA) as dynam-ic damping mostly decreases due to pipeline effect, which also happens on ground effect model, however, as the blockage effect at large AOA, both the dynamic stability of airfoil flying over ground and water sur-face are improved, besides, compared to ground, water affects a wider range to unsteady aerodynamics of airfoil.