基于FlowStar软件的栅格舵气动特性模拟

Aerodynamic characteristics simulation of grid rudder using FlowStar software

栅格舵是由外部边框和内部若干薄栅格组成的一种新型气动力面和控制面。由于其具有尺寸小、重量轻和易折叠等结构特点,以及升力特性好、铰链力矩小和压心位置随马赫数变化小等良好的气动性能,越来越受到重视和广泛应用。但是,由于栅格舵是特殊的蜂窝结构,常规的结构网格生成困难,并且栅格壁之间存在严重的波系干扰,流场结构复杂,给数值模拟带来了挑战。本文针对栅格舵流场结构复杂、网格生成和数值模拟难度大的难题,采用国家数值风洞工程(NNW)项目团队自主开发的非结构混合网格流场软件FlowStar,对栅格舵气动特性开展了数值模拟研究。首先,通过十字栅格舵全弹标模外形,验证了数值模拟方法的可靠性。然后,通过研究栅格不同形状对栅格舵气动特性的影响规律,给出了栅格舵设计时尽量采用气动性能较高和结构强度较好的菱形栅格,以及尽可能少用或不用正三角形栅格的指导建议。最后,开展了类Space X迎风面局部弧形栅格舵气动特性模拟研究,结果表明,弧形后掠可以有效降低阻力,提高升阻比;攻角为0°时,与平直栅格舵相比,弧形后掠栅格舵在亚跨声速阶段,阻力降低约8%,马赫数大于2时,阻力降低约15%。本文研究可为栅格舵的设计提供参考和指导。

A grid rudder is an unconventional lifting and control surface that consists of an outer frame and many inner grid walls.Due to its small size, light weight, easiness to fold and other structural characteristics, as well as good aerodynamic performance such as good lift characteristics, small hinge moment, and small change of pressure center position with Mach number, grid rudder has been paid more and more attention to and widely used.However, it is difficult to generate the conventional structure grid for grid rudder because of its special honeycomb, and there are serious wave system interferences between the grid walls, and the flow field structure is complex, which bring challenges to the numerical simulation methods.In this paper, the numerical simulation of aerodynamic characteristics of grid rudder is carried out by using the unstructured hybrid gird flow software named FlowStar, which is developed by the National Numerical Wind tunnel(NNW) team.Firstly, the reliability of the numerical simulation method is verified by the standard mold shape of the cross grid rudder missile.Then, it is proposed that the diamond shape with high aerodynamic performance and good structural strength should be used as much as possible in the design of the grid rudder while the regular triangle shape should not be used or be used as little as possible by studying the influence of different shapes of the grid rudder on the aerodynamic characteristics.Finally, the aerodynamic characteristics simulation study is presented for the grid rudder as Space X’s with local arc shape on the windward surface.The results show that the arc-shaped sweep can effectively reduce drag and increase the lift-to-drag ratio.Compared with the straight configuration, at angle of 0 degree, the drag of grid rudder with the arc-shaped sweep is reduced by about 8% in subsonic and transonic stages, and by about 15% when the Mach number is greater than 2.The research in this paper can provide reference and guidance for the design of grid rudder.