The surging interest in planetary exploration underscores the need for deployable aerodynamic decelerators with a low ballistic coefficient.This study introduces a novel approach to designing and constructing mechanic...The surging interest in planetary exploration underscores the need for deployable aerodynamic decelerators with a low ballistic coefficient.This study introduces a novel approach to designing and constructing mechanically deployable aerodynamic decelerators(MDADs)that utilize an umbrella-like mechanism and proposes a new mechanism of MDADs through this method.The proposed method utilizes plane-symmetric 7R(R:revolute joint)linkages,and the kinematics of these linkages are systematically analyzed using the product of exponentials method.The 7R linkage kinematics are equated to an equivalent joint,the foundation for constructing umbrella-like deployable mechanisms.Three distinct types of mechanisms are synthesized using this methodology.Subsequently,their kinematics are analyzed based on the equivalent joint,and the configurations are experimentally validated through 3D-printed models and kinematic simulations.Trajectory simulations and structural analyses are conducted to assess the performance of the deployable mechanisms and provide valuable insights into their capabilities.This research contributes to advancing deployable aerodynamic decelerator technology and offers a promising avenue for future planetary entry,descent,and landing applications.展开更多
At present, the key technical researches are carried out for the future exploration missions to dense atmosphere planets such as Jupiter. As a necessary aerodynamic decelerator for planetary exploration missions with ...At present, the key technical researches are carried out for the future exploration missions to dense atmosphere planets such as Jupiter. As a necessary aerodynamic decelerator for planetary exploration missions with dense atmosphere, parachutes face several big challenges, such as complex transonic/supersonic unsteady aerodynamic characteristics. Thus, it is necessary to study deeply and make clear the transonic/supersonic unsteady flow mechanisms around the parachute systems and its aerodynamic characteristics;however, these are still unknown to date. In this study, parachute structure systems are designed based on the Galileo exploration mission. Using the parachute models, the numerical simulations were conducted to investigate the complex flow phenomena and unsteady aerodynamics of parachute systems with different diameter ratios of capsule to canopy, under different freestream Mach numbers. As a result, it is found that when a parachute 2-body model with a bigger diameter ratio of capsule to canopy is placed in transonic flows, the wake of the forebody (capsule) is strong, and the shock wave in front of the canopy is weak. When the canopy shock moves upstream, the pressure fluctuation inside the canopy surface exhibits 3 stages of changes: high-frequency large-amplitude, low-frequency small-amplitude, and high-frequency small-amplitude. It is also found that in the supersonic flow cases, the amplitude and frequency of pressure fluctuations inside the canopy increase significantly, especially at Mach 2.0. This is due to the strong interactions between the shedding vortex of the wake and the shock wave in front of the canopy. However, for the parachute model with a small diameter ratio, the important shock waves in front of the canopy is not observed, and high-frequency and small-amplitude pressure variations remain, which is affected directly by the frequency and intensity of wake vortex shedding. In summary, as the Mach number increases, the amplitude and frequency of pressure fluctuations increase, and the average pressure distribution also increases, and the law of its influence becomes more complex.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52175010)the Self-Planned Task of the State Key Laboratory of Robotics and Systems,Harbin Institute of Technology,China(Grant No.SKLRS202202B).
文摘The surging interest in planetary exploration underscores the need for deployable aerodynamic decelerators with a low ballistic coefficient.This study introduces a novel approach to designing and constructing mechanically deployable aerodynamic decelerators(MDADs)that utilize an umbrella-like mechanism and proposes a new mechanism of MDADs through this method.The proposed method utilizes plane-symmetric 7R(R:revolute joint)linkages,and the kinematics of these linkages are systematically analyzed using the product of exponentials method.The 7R linkage kinematics are equated to an equivalent joint,the foundation for constructing umbrella-like deployable mechanisms.Three distinct types of mechanisms are synthesized using this methodology.Subsequently,their kinematics are analyzed based on the equivalent joint,and the configurations are experimentally validated through 3D-printed models and kinematic simulations.Trajectory simulations and structural analyses are conducted to assess the performance of the deployable mechanisms and provide valuable insights into their capabilities.This research contributes to advancing deployable aerodynamic decelerator technology and offers a promising avenue for future planetary entry,descent,and landing applications.
基金supported by the National Natural Science Foundation of China (Grant No. 11972192).
文摘At present, the key technical researches are carried out for the future exploration missions to dense atmosphere planets such as Jupiter. As a necessary aerodynamic decelerator for planetary exploration missions with dense atmosphere, parachutes face several big challenges, such as complex transonic/supersonic unsteady aerodynamic characteristics. Thus, it is necessary to study deeply and make clear the transonic/supersonic unsteady flow mechanisms around the parachute systems and its aerodynamic characteristics;however, these are still unknown to date. In this study, parachute structure systems are designed based on the Galileo exploration mission. Using the parachute models, the numerical simulations were conducted to investigate the complex flow phenomena and unsteady aerodynamics of parachute systems with different diameter ratios of capsule to canopy, under different freestream Mach numbers. As a result, it is found that when a parachute 2-body model with a bigger diameter ratio of capsule to canopy is placed in transonic flows, the wake of the forebody (capsule) is strong, and the shock wave in front of the canopy is weak. When the canopy shock moves upstream, the pressure fluctuation inside the canopy surface exhibits 3 stages of changes: high-frequency large-amplitude, low-frequency small-amplitude, and high-frequency small-amplitude. It is also found that in the supersonic flow cases, the amplitude and frequency of pressure fluctuations inside the canopy increase significantly, especially at Mach 2.0. This is due to the strong interactions between the shedding vortex of the wake and the shock wave in front of the canopy. However, for the parachute model with a small diameter ratio, the important shock waves in front of the canopy is not observed, and high-frequency and small-amplitude pressure variations remain, which is affected directly by the frequency and intensity of wake vortex shedding. In summary, as the Mach number increases, the amplitude and frequency of pressure fluctuations increase, and the average pressure distribution also increases, and the law of its influence becomes more complex.
