A high-resolution numerical investigation of unsteady wake vortices for coaxial rotors in hover  

作　　者：Shaoqiang HAN Wenping SONG Zhonghua HAN Jianhua XU 

机构地区：[1]Tianfu Engineering-oriented Numerical&Software Innovation Center,College of Computer Science,Sichuan University,Chengdu 610065,China [2]National Key Laboratory of Science and Technology on Aerodynamic Design and Research,School of Aeronautics,Northwestern Polytechnical University,Xi’an 710072,China

出　　处：《Chinese Journal of Aeronautics》2024年第11期278-299,共22页中国航空学报（英文版）

摘　　要：High-resolution numerical simulations for wake vortical flows have long been a challenge in rotor aerodynamics.A novel spectrum-optimized sixth-order Weighted Essentially NonOscillatory(WENO)scheme is proposed to discretize inviscid fluxes on moving overset grids,and the Improved Delayed Detached Eddy Simulation(IDDES)is employed to resolve turbulent vortices.The integration of these methods facilitates a comprehensive numerical investigation into the unsteady vortical flows over coaxial rotors in hover.The results highlight the substantial improvement in numerical resolution,in terms of both spatial structure and temporal evolution of unsteady multiscale wake vortices.Coaxial rotors in hover manifest three primary scales of wake vortex structures:(A)the helical evolution of primary blade tip vortices and the periodic occurrence of strong Blade-Vortex Interactions(BVI);(B)the continuous shedding of small-scale horseshoeshaped vortices from the trailing edges of rotor blades,forming the vortex sheets;(C)the emergence of small-scale secondary vortex braids induced by interactions between rotor tip vortices and the vortex sheets.These vortex structures and their interactions cause high-frequency oscillations in rotor disk loads and induce unsteady perturbations in the local flow field.Interactions among these primary vortices,coupled with the generation of secondary vortices,result in the dissipation,distortion,and breakup of the rotor tip vortices,ultimately forming a vortex soup.Notably,a substantial quantity of seemingly weak small-scale secondary vortex braids significantly contribute to energy dissipation during the evolution of wake vortices for coaxial rotors in hover.ó2024 Chinese Society of Aeronautics and Astronautics.Production and hosting by Elsevier Ltd.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

关 键 词：Coaxial rotor Blade tip vortex Secondary vortex High-order scheme IDDES Moving overset grid 

分 类 号：V211.52[航空宇航科学与技术—航空宇航推进理论与工程]