基于改进混合长度尺度的机翼延迟分离涡模拟  

The DDES around Wing Based on Improved Mixed Length Scale

作　　者：丘德新 王良军 张武[1,3] Qiu Dexin;Wang Liangjun;Zhang Wu(School of Mechanics and Engineering Science,Shanghai University,Shanghai 200072,China;Information Technology Office,Shanghai University,Shanghai 200444,China;Shanghai Institute of Applied Mathematics and Mechanics,Shanghai University,Shanghai 200072,China)

机构地区：[1]上海大学力学与工程科学学院,上海200072 [2]上海大学信息化工作办公室,上海200444 [3]上海大学上海市应用数学和力学研究所,上海200072

出　　处：《航空兵器》2022年第4期70-76,共7页Aero Weaponry

基　　金：国家自然科学基金重大研究计划重点项目(91630206)。

摘　　要：对于中小迎角分离问题,延迟分离涡模拟(Delayed Detached Eddy Simulation,DDES)的方法在计算初期,流动分离区需要一定时间的发展,通常会延迟RANS模式到LES模式的切换,从而低估流动分离。本文采用改进RANS-LES混合长度尺度l_(hyb_new)的方法,对网格尺度和涡探测函数VTM进行修正,基于计算流体力学开源平台OpenFOAM,将修正后的混合网格尺度、涡探测函数VTM_(new)以及二维剪切层识别函数F_(KH)(VTM_(new))植入到S-A DDES模型中,研究了大迎角NACA0012翼型以及12°迎角下的NACA0012半展长矩形机翼绕流问题,并对比了采用原S-A DDES和改进RANS-LES混合长度尺度后的S-A DDES湍流模型计算的机翼背风区涡结构和翼尖涡。结果表明,采用本文方法可以在机翼背风区观察到剪切层的快速失稳,并且能够更加精细地模拟机翼背风区的大尺度非定常涡系结构以及翼尖涡的形成细节,有效地加快DDES方法的RANS模式切换到LES模式。此外,本文还计算了该矩形机翼在18°迎角的分离流问题,进一步验证了所提方法的有效适应性。For the separation problem at small and medium angles of attack,in the early stage of DDES(Delayed Detached Eddy Simulation)method,it takes some time for the flow separation region to develop,and usually delays the switch from RANS mode to LES mode,so as to underestimate the flow separation.An improved RANS-LES hybrid length scale method is adopted to modify the grid scale and vortex tilting measure(VTM)function in this paper.Based on open source CFD software OpenFOAM,the modified hybrid grid scale,vortex tilting measure(VTM_(new))function and two-dimensional shear layer identification function F_(KH)(VTM_(new))are implanted into the S-A DDES model to study the flow around NACA0012 airfoil at high angle of attack and NACA0012 half span rectangular wing at angle of attack 12°.The vortex structure and tip vortex in the leeward region of the wing calculated by the original S-A DDES and the S-A DDES turbulence model with improved RANS-LES mixing length scale are compared.The results show that the rapid instability of the shear layer can be observed in the leeward region of the wing by using the proposed method,and the large-scale unsteady vortex system structure and the formation details of the wing tip vortex in the leeward region can be simulated more finely,which can effectively speed up the switching from RANS mode to LES mode of DDES method.In addition,the separated flow problem of the rectangular wing at angle of attack 18°is calculated,which further verifies the effective adaptability of the proposed method.

关 键 词：延迟分离涡模拟 非定常流动 RANS LES 翼尖涡 OPENFOAM 空气动力学 

分 类 号：TJ760[兵器科学与技术—武器系统与运用工程] V211.41[航空宇航科学与技术—航空宇航推进理论与工程]