基于大涡模拟的螺旋桨毂帽鳍系统精细流场数值研究

Numerical Research of the Flow Influenced by Boss Cap Fin under Propeller Based on the LES Method

对引起螺旋桨毂帽鳍系统推进性能变化的细节及流动本质问题的研究,有助于对毂帽鳍的节能机理产生新的认识,并为改进该系统的推进性能提供新的思路。通过模型试验和大涡模拟方法对螺旋桨毂帽鳍系统进行了力的测量及精细流场的分析,从能量的角度,分析了毂帽鳍节能机理。数值模拟显示,在毂帽鳍的作用下,在紧邻桨毂后方区域的流速比无毂帽鳍时小且低速区域更广,桨毂后方流体轴向和横向动能均有所减小。由此可知,毂帽鳍通过回收一部分螺旋桨释放在尾流中的动能实现节能;在桨毂后安装一种圆锥形导流帽可避免流动分离,能进一步提高推进系统的整体效率。

The study of the flow details and the essence of the flow that cause the macroscopic changes in the propulsion performance of the propeller boss cap fin system will help to generate new understanding of the energy saving mechanism of this system and provide new ideas for improving it's propulsion performance.In this paper,the macroscopic force measurement and fine flow field analysis of the cap fin system were carried out by conducting model tests and numerical simulations based on the large eddy simulation method.From the perspective of energy,the energy-saving mechanism of propeller boss cap fin was analyzed.Numerical simulation showed that under the action of propeller boss cap fin,the flow velocity in the area immediately behind the hub was smaller than that without propeller boss cap fin,and the low-speed area was wider;under the effect of propeller boss cap fin,the axial kinetic energy and transverse kinetic energy of the fluid behind the hub were both reduced.This paper believes that propeller boss cap fin achieves energy-saving effect by recovering part of the kinetic energy released by propeller in the wake;installing a streamlined cap behind the hub can avoid flow separation and further improve the overall efficiency of propulsion system.