基于非光滑表面的直升机尾舱门减阻技术

Helicopter Backdoor Drag Reduction Technology Based on Non-smooth Surface

为了研究凹坑形非光滑表面的减阻效果与流动控制机理,将半球形凹坑单元布置在直升机尾舱门外表面。采用基于k-ω剪切应力输运模型(k-ω shear-stress-transport,k-ω SST)的计算流体力学(Computational fluid dynamics,CFD)方法,对比分析了非光滑表面机身和光滑表面机身的阻力特性、后体局部流场和表面压力分布。根据凹坑单元内局部流场和压力分布的分析结果,得到了凹坑形非光滑表面的减阻机理:凹坑单元内形成的低速漩涡,能够延缓机身后体流动分离;半球形的凹坑造型和基本恒定的压力分布,可减小对阻力直接做出贡献的低压区面积,两者的共同作用降低了直升机阻力。

In order to study the effect and the flow control mechanism of the dimple non-smooth surface,hemispherical dimple units were arranged in the out surface of the backdoor. The method of computational fluid dynamics(CFD)numerical simulation based on k-ω shear-stress-transport(k-ω SST)model was used to comparatively analyze the resistance characteristic,local flow field of after-body and pressure distribution of the smooth and non-smooth fuselage. According to the analysis of the local flow field and pressure distribution of the dimple,the drag reduction mechanism was obtained that the low vortex in the dimple was able to delay flow separation and the hemispherical dimple and pressure distribution of approximately constant could reduce the area of low pressure related to drag,the results of both were reducing the fuselage drag.