Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study ...Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study the downwash flow’s effect on the stability of the FWR.After simulation,a cone like self-lock region which acts as the critical condition determining the stability of FWR is found.Only when the flow’s resultant velocity acting on the control surface lies in the stable region,the FWR can keep stable.The size of the cone like self-lock stable region can be enlarged by increasing the maximum feasible deflection angle constrained by mechanical design or enhancing the equivalent downwash flow velocity.Among all the simulated cases,when J=2.67(f=5 Hz,■=5 r/s),the largest average equivalent downwash flow velocities are found.On the other hand,the recovery torque could be enhanced due to the increase of the arm of the lateral force.According to these simulation results,a 43 g FWR model with two control surfaces and two stabilizers is then designed.A series of flight tests is then conducted to help confirm the conclusion of the mechanism research in this work.Overall,this study points out several strategies to increase the flight stability of the FWR and finally realizes the stable climb flight and mild descent flight of the FWR.展开更多
To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the v...To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the variation amplitude of the twist angles on the FWR remains unknown.In this study,a 19.2-g FWR model is designed and manufactured.Three different kinds of springs are then selected and assembled onto the FWR to reduce the energy consumption caused by the inertial forces.Afterward,a motion capture system and a lift measurement system are built to test the aerodynamic and kinematic performance of the FWR.Then,the influence of the variation range of the twist angles and the dimensions of the spring on the motion parameters and lift efficiency of the FWR is analyzed.If the rigid twist angle variation range is set to 10°–70°instead of 10°–50°,the FWR can generate 3 to 10 g of greater average lifts under the same input voltage.In most cases,the introduction of the spring also improves the average lifting rate by 1-4 g.The lift enhancement effect induced by the spring is more pronounced when the main frequency with the maximum amplitude is close to or coincides with the resonant frequency of the FWR structure.If the main frequency is greater than the resonance frequency of the FWR structure,the lift enhancement effect is hardly observed.In conclusion,according to experimental analyses,both the selection of 10°-70°preset twist angles and the application of springs can improve the lift efficiency of FWR and overcome the weight of the FWR system(37.8 g)assembled with a flight control system.Free-flight test results show that the FWR system(including the 19.2-g FWR model and an 18.6-g flight control system)has sufficient lifting margin to successfully perform a take-off mission and achieve a stable hovering action.展开更多
基金supported by the following funding organizations in China:National Natural Science Foundation of China(Grant No.52375116 and Grant No.52105285)the Aeronautical Science Foundation of China(Grant No.ASFC-20230023052001)+3 种基金China Postdoctoral Science Foundation(Grant No.2024M754237)National Key Research and Development Program of China(2024YFB470920001)Science and Technology Plan Project of Wenzhou Municipality(Grant No.ZG2024001)Basic Public Welfare Research Program of Wenzhou(Grant No.G2023046).
文摘Throughout the previous studies,none of them are involved in analysing the downwash flow effect on the control surface of the Flapping Wing Rotor(FWR).An overset CFD numerical model is built up and validated to study the downwash flow’s effect on the stability of the FWR.After simulation,a cone like self-lock region which acts as the critical condition determining the stability of FWR is found.Only when the flow’s resultant velocity acting on the control surface lies in the stable region,the FWR can keep stable.The size of the cone like self-lock stable region can be enlarged by increasing the maximum feasible deflection angle constrained by mechanical design or enhancing the equivalent downwash flow velocity.Among all the simulated cases,when J=2.67(f=5 Hz,■=5 r/s),the largest average equivalent downwash flow velocities are found.On the other hand,the recovery torque could be enhanced due to the increase of the arm of the lateral force.According to these simulation results,a 43 g FWR model with two control surfaces and two stabilizers is then designed.A series of flight tests is then conducted to help confirm the conclusion of the mechanism research in this work.Overall,this study points out several strategies to increase the flight stability of the FWR and finally realizes the stable climb flight and mild descent flight of the FWR.
基金supported by the Natural Science Foundation of Zhejiang Province(Grant No.LQ22A020006)the National Natural Science Foundation of China(Grant No.52105285)+3 种基金the Aeronautical Science Foundation Program(Grant No.ASFC-20230023052001)China Postdoctoral Science Foundation(Grant No.2024M754237)Science and Technology Project of Jiangxi Education Department(Grant No.GJJ200452)Basic Public Welfare Research Program of Wenzhou(Grant No.G2023046)。
文摘To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the variation amplitude of the twist angles on the FWR remains unknown.In this study,a 19.2-g FWR model is designed and manufactured.Three different kinds of springs are then selected and assembled onto the FWR to reduce the energy consumption caused by the inertial forces.Afterward,a motion capture system and a lift measurement system are built to test the aerodynamic and kinematic performance of the FWR.Then,the influence of the variation range of the twist angles and the dimensions of the spring on the motion parameters and lift efficiency of the FWR is analyzed.If the rigid twist angle variation range is set to 10°–70°instead of 10°–50°,the FWR can generate 3 to 10 g of greater average lifts under the same input voltage.In most cases,the introduction of the spring also improves the average lifting rate by 1-4 g.The lift enhancement effect induced by the spring is more pronounced when the main frequency with the maximum amplitude is close to or coincides with the resonant frequency of the FWR structure.If the main frequency is greater than the resonance frequency of the FWR structure,the lift enhancement effect is hardly observed.In conclusion,according to experimental analyses,both the selection of 10°-70°preset twist angles and the application of springs can improve the lift efficiency of FWR and overcome the weight of the FWR system(37.8 g)assembled with a flight control system.Free-flight test results show that the FWR system(including the 19.2-g FWR model and an 18.6-g flight control system)has sufficient lifting margin to successfully perform a take-off mission and achieve a stable hovering action.
