Abstract
The air flow field of ship was simulated by using computational fluid dynamics technology to analyze its prime characteristics with reasonable accuracy. The different results of Reynolds-Averaged Navier-Stokes (RANS) method and Detached Eddy Simulation (DES) were compared, and the calculation traits of these methods were discussed. The results show that the air flow field of ship is unsteady. The accuracy of RANS simulation is insufficient for capturing this unsteady phenomenon. However, DES can catch this with better accuracy and expresses a comparatively great conformity with experimental data. Then, the aircraft carrier's flow field was calculated by DES. The characteristics of vortexes and velocity fluctuation on the ideal landing track were discussed in different wind directions. Those simulations indicate that there are complicated vortexes produced by blunt edges of the island and deck in the flow field. Those vortexes interact and mainly exist in the rear of flight deck and its adjacent air wake. Moreover, they cause a conspicuous and periodical velocity fluctuation on the ideal landing track as time goes on.
Highlights
The results show that the air flow field of ship is unsteady
本文对比了不同数值方法对舰船空气流场的模 拟结果,对舰船空气流场数值模拟方法及流场特征 进行了探索,得出的结论如下: 1) 舰船空气流场体现出非稳态特征, 基 于 RANS 的非定常计算并不能够模拟出该特征,但基 于 RANS 定常计算得到的流场结构与 DES 方法取 得的时均结果相似。 而基于 DES 的数值模拟能够 较好地捕捉舰船空气流场中涡的生成和发展,其中 基于 k⁃ω SST 湍流模型的 DES⁃SST 方法所得结果更 为准确; 2) 航母流场中最为突出的是舰岛处周期性脱 落的涡,及其与甲板边缘、尾部涡流相互作用形成的 复杂涡系。 这些涡流在舰载机进舰轨迹上引起较为 强烈的且随着时间推进的速度波动,导致在航母后 部甲板及其临近的尾流区产生大的侧风及上下洗变 化,其中甲板末端表现最为显著; 3) 不同风向下,航母甲板受涡流影响的区域范 围不同,其中左舷 9°风向下舰载机进舰轨迹区域的 涡流相对较少,且进舰轨迹上的时均速度波动较为 平缓,对舰载机着舰有利。
Summary
郭佳豪1, 祝小平2, 周洲1, 许晓平1 (1.西北工业大学 航空学院, 陕西 西安 710072; 2.西北工业大学 无人机特种技术重点实验室, 陕西 西安 710065) 本文将分别采用 RANS 与 DES 方法,对比其在 舰船空气流场研究中的特点。 并通过 DES 数值模 拟方法分析航母空气流场的主要特征及复杂流动在 舰载机进舰轨迹上引起的速度波动,以此探究舰载 机的着舰环境。 DES 方 法 是 将 RANS 与大涡模拟 ( large eddy simulation,LES) 结合起来进行求解的一种混合方 法[17⁃18] 。 其将 RANS 湍流模型中的长度尺度 lR 与
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