Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficien...Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficiency at an altitude of 22 km,a certain near-space composite propeller is designed as a long and slender aerodynamic shape with a 10 m diameter,which brings many challenges to the composite structure design.The initial design is obtained by the composite structure variable stiffness design method using based on fixed region division blending model.However,it weighs 23.142 kg,exceeding the required 20 kg.In order to meet the structural design requirements of the propeller,a variable stiffness design method using the adaptive region division blending model is proposed in this paper.Compared with the methods using the fixed region division blending model,this method optimizes region division,stacking thickness and stacking sequence in a single level,considering the coupling effect among them.Through a more refined region division,this method can provide a more optimal design for composite tapered structures.Additionally,to improve the efficiency of optimization subjected to manufacturing constraints,a hierarchical penalty function is proposed to quickly filter out the solutions that do not meet manufacturing constraints.The above methods combined with a Genetic Algorithm(GA)using specific encoding are adopted to optimize the near-space composite propeller.The optimal design of the structure weighs 18.831 kg,with all manufacturing constraints and all structural response constraints being satisfied.Compared with the initial design,the optimal design has a more refined region division,and achieves a weight reduction of 18.6%.This demonstrates that a refined region division can significantly improve the mechanical performance of the composite tapered structure.展开更多
Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by...Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.展开更多
基金This study was co-supported by stable funding from the National Key Laboratory of Aerofoil and Grille Aerodynamics,China.
文摘Near-space airship is a frontier and hotspot in current military research and development,and the near-space composite propeller is the key technology for its development.In order to obtain higher aerodynamic efficiency at an altitude of 22 km,a certain near-space composite propeller is designed as a long and slender aerodynamic shape with a 10 m diameter,which brings many challenges to the composite structure design.The initial design is obtained by the composite structure variable stiffness design method using based on fixed region division blending model.However,it weighs 23.142 kg,exceeding the required 20 kg.In order to meet the structural design requirements of the propeller,a variable stiffness design method using the adaptive region division blending model is proposed in this paper.Compared with the methods using the fixed region division blending model,this method optimizes region division,stacking thickness and stacking sequence in a single level,considering the coupling effect among them.Through a more refined region division,this method can provide a more optimal design for composite tapered structures.Additionally,to improve the efficiency of optimization subjected to manufacturing constraints,a hierarchical penalty function is proposed to quickly filter out the solutions that do not meet manufacturing constraints.The above methods combined with a Genetic Algorithm(GA)using specific encoding are adopted to optimize the near-space composite propeller.The optimal design of the structure weighs 18.831 kg,with all manufacturing constraints and all structural response constraints being satisfied.Compared with the initial design,the optimal design has a more refined region division,and achieves a weight reduction of 18.6%.This demonstrates that a refined region division can significantly improve the mechanical performance of the composite tapered structure.
基金sponsored by Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2024037)。
文摘Dynamic soaring,which harvests energy from the wind,can enhance Unmanned Aerial Vehicles'(UAVs')range and endurance.However,energy harvesting efficiency issues hinder UAV applications,which can be addressed by wing morphing.Therefore,this study investigates the influence of albatross wing morphing during dynamic soaring.By constructing a parametric model,the shape of the albatross wing can be modeled and achieve morphing based on joints.From the video data,this paper summarizes the typical wing morphing patterns of the albatross and notices that changes primarily occur during the leeward descent phase.This paper first analyzes the aerodynamic performance of different wing morphing patterns and finds that the drag coefficient can be reduced by 7.75%with a suitable morphing pattern.This paper also explores the drag coefficient reduction mechanism and finds that downwash airflow decreases by 30.32%after wingtip anhedral.Interestingly,the lift-to-drag ratio shows minimal variation under different morphing patterns,within 2%.From the stability perspective,this study finds that the neutral point position changes after morphing.The maximum longitudinal static margin change is 4.9%,enhancing longitudinal stability by increasing the restorative moment arm.The lateral neutral point is 4.87%closer to the center of gravity,decreasing the roll and yaw moments.It can be observed that wingtip anhedral significantly increases the stability of the albatross.Moreover,a flight simulation is carried out to study the morphing influence on trajectory and energy harvesting.The results show that maximum energy gained is improved by 47.99%,and endurance is increased by 13.05%.The results also indicate that the effects of wing morphing are global rather than limited to the phase of morphing occurrence.Finally,based on the results,this paper proposes wing morphing regularity about the wingtip for UAVs.Wingtip bends downward can significantly increase the UAVs'stability and reduce drag,but the overall trajectory needs to be reconsidered after introducing wing morphing.
