Graphene platelets(GPLs)-reinforced metal foam structures enhance the mechanical properties while maintaining the lightweight characteristics of metal foams.Further bonding piezoelectric actuator and sensor layers on ...Graphene platelets(GPLs)-reinforced metal foam structures enhance the mechanical properties while maintaining the lightweight characteristics of metal foams.Further bonding piezoelectric actuator and sensor layers on the surfaces of GPLs-reinforced metal foam beams enables active vibration control,greatly expanding their applications in the aerospace industry.For the first time,this paper investigates the vibration characteristics and active vibration control of GPLs-reinforced metal foam beams with surfacebonded piezoelectric layers.The constant velocity feedback scheme is used to design the closed-loop controller including piezoelectric actuators and sensors.The effects of the GPLs on the linear and nonlinear free vibrations of the beams are numerically studied.The Newmark-βmethod combined with Newton's iteration technique is used to calculate the nonlinear responses of the beams under different load forms including harmonic loads,impact loads,and moving loads.Additionally,special attention is given to the vibration reduction performance of the velocity feedback control on the responses of the beam.展开更多
Efficient fluid mixing is essential for process intensification.This study proposes a new method in which gas-rigid-flexible composite blades are coupled to enhance chaotic mixing in multiphase flow systems.The rigidi...Efficient fluid mixing is essential for process intensification.This study proposes a new method in which gas-rigid-flexible composite blades are coupled to enhance chaotic mixing in multiphase flow systems.The rigidity and flexibility of the blades were adjusted by intermittent gas injection,which increased the effectiveness of mixing of the liquid-liquid two-phase fluid.This study investigates the influence of different process parameters on the mixing efficiency and quantifies the chaotic characteristics of fluid mixing through pressure-time series analysis of multiscale entropy and the 0–1 test.A high-speed camera recorded the bubble movement in the flow field,while particle image velocimetry(PIV)revealed the enhancement of the properties of the flow field in the system due to the suspended motion of the particles.Using suitable process parameters,gas-rigid-flexible composite blade coupling significantly enhanced the mixing effect,where the mixing time of the G-RFCP system was reduced by 1.42 times compared to that of the CP system.Bubble motion,deformation,and rupture enhanced the mechanical agitation,increasing the intensity of the turbulence and chaotic behaviour.Flow-field analysis indicated a three-fold increase in the vorticity and a 1.04-fold increase in the velocity difference for the G-RFCP system compared with those of the CP system.This study provides theoretical and experimental foundations for understanding chaotic mixing in liquid-liquid two-phase fluids.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.12102015 and 12472003)the R&D Program of Beijing Municipal Education Commission of China(No.KM202110005030)。
文摘Graphene platelets(GPLs)-reinforced metal foam structures enhance the mechanical properties while maintaining the lightweight characteristics of metal foams.Further bonding piezoelectric actuator and sensor layers on the surfaces of GPLs-reinforced metal foam beams enables active vibration control,greatly expanding their applications in the aerospace industry.For the first time,this paper investigates the vibration characteristics and active vibration control of GPLs-reinforced metal foam beams with surfacebonded piezoelectric layers.The constant velocity feedback scheme is used to design the closed-loop controller including piezoelectric actuators and sensors.The effects of the GPLs on the linear and nonlinear free vibrations of the beams are numerically studied.The Newmark-βmethod combined with Newton's iteration technique is used to calculate the nonlinear responses of the beams under different load forms including harmonic loads,impact loads,and moving loads.Additionally,special attention is given to the vibration reduction performance of the velocity feedback control on the responses of the beam.
基金supports by the National Natural Science Foundation of China(project No.52166004)National key research and development plan project(project No.2022YFC3902000)Yunnan Major Scientific and Technological Projects(grant Nos.202202AG050007,202202AG050002).
文摘Efficient fluid mixing is essential for process intensification.This study proposes a new method in which gas-rigid-flexible composite blades are coupled to enhance chaotic mixing in multiphase flow systems.The rigidity and flexibility of the blades were adjusted by intermittent gas injection,which increased the effectiveness of mixing of the liquid-liquid two-phase fluid.This study investigates the influence of different process parameters on the mixing efficiency and quantifies the chaotic characteristics of fluid mixing through pressure-time series analysis of multiscale entropy and the 0–1 test.A high-speed camera recorded the bubble movement in the flow field,while particle image velocimetry(PIV)revealed the enhancement of the properties of the flow field in the system due to the suspended motion of the particles.Using suitable process parameters,gas-rigid-flexible composite blade coupling significantly enhanced the mixing effect,where the mixing time of the G-RFCP system was reduced by 1.42 times compared to that of the CP system.Bubble motion,deformation,and rupture enhanced the mechanical agitation,increasing the intensity of the turbulence and chaotic behaviour.Flow-field analysis indicated a three-fold increase in the vorticity and a 1.04-fold increase in the velocity difference for the G-RFCP system compared with those of the CP system.This study provides theoretical and experimental foundations for understanding chaotic mixing in liquid-liquid two-phase fluids.
