Mechanism analysis of hysteretic aerodynamic characteristics on variable-sweep wings

作     者：Lifang ZENG Liu LIU Xueming SHAO Jun LI Lifang ZENG;Liu LIU;Xueming SHAO;Jun LI

作者机构：Zhejiang UniversityHangzhou 310027China Rotor Aerodynamics Key LaboratoryChina Aerodynamics Research and Development CenterMianyang 621000China 

出 版 物：《Chinese Journal of Aeronautics》 (中国航空学报（英文版）)

年 卷 期：2023年第36卷第5期

页      面：212-222页

核心收录：

学科分类：0711[理学-系统科学] 08[工学] 080103[工学-流体力学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(No.12202384) the Rotor Aerodynamics Key Laboratory Foundation of China Aerodynamics Research and Development Center(No.2108RAL202102-5). 

主　　题：Hysteresis Mechanism Numerical simulation Unsteady aerodynamic characteristics Variable-sweep wings 

摘      要：Variable-sweep wings have large shape-changing capabilities and wide flight envelops,which are considered as one of the most promising directions for intelligent morphing UAVs.Aerodynamic investigations always focus on several static states in the varying sweep process,which ignore the unsteady aerodynamic characteristics.However,deviations to static aerodynamic forces are inevitably caused by dynamic sweep motion.In this work,first,unsteady aerodynamic characteristics on a typical variable-sweep UAV with large aspect ratio were analyzed.Then,deep mechanism of unsteady aerodynamic characteristics in the varying sweep process was studied.Finally,numerical simulation method integrated with structured moving overset grids was applied to solve the unsteady fluid of varying sweep process.The simulation results of a sweep forward-backward circle show a distinct dynamic hysteresis loop surrounding the static data for the aerodynamic forces.Compared with the static lift coefficients,at the same sweep angles,dynamic lift coefficient in sweep forward process are all smaller,while dynamic sweep backward lift coefficient are all larger.In addition,dynamic deviations to static lift coefficient are positively related with the varying sweep speeds.Mechanism study on the unsteady aerodynamic characteristics indicates that three key factors lead to the dynamic hysteresis loop in varying sweep process.They are the effects of additional velocity caused by varying sweep motion,the effects of flow hysteresis and viscosity.The additional velocity induced by sweep motion affects the transversal flow direction along the wing and the effective angle of attack at the airfoil profile.The physical properties of flow,the hysteresis and viscosity affect the unsteady aerodynamic characteristics by flow separation and induced vortexes.