There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing ...There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing components.However,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting mode.For REBs,high rotational speed and long service life are two performance indexes that mutually restrict each other.To go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the REB.This review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of REBs.Then,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized comprehensively.These promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our team.Our more than ten years of relevant research on fluid-film and magnetic bearings are also introduced.This review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.展开更多
An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric ...An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric Powered Descent Guidance with Disturbance Rejection(Endo-PDG-DR).The key idea of formulating the Endo-PDG-DR problem is dividing disturbances into two parts,modeled and unmodeled disturbances:the modeled disturbance is proactively exploited by augmenting it as a new state of a dynamics model;the unmodeled disturbance is reactively attenuated in terms of its effect on the guidance performance by adjoining a parameterized time-varying quadratic performance index in the proposed optimal guidance problem.A Pseudospectral Differential Dynamic Programming(PDDP)method is developed to solve the Endo-PDG-DR problem,and correspondingly a robust neighboring optimal state feedback law is obtained,which has two synergistic functionalities.One is adaptive optimal steering to accommodate the modeled disturbance,and the other is disturbance attenuation to compensate for the state perturbation effect induced by the unmodeled disturbance.Using the derived feedback guidance law,a disturbance rejection level is quantified,and is correspondingly optimized by designing a quadratic weighting parameter tuning law.The numerical computations of interest are performed within a pseudospectral setting,ensuring polynomial analytical solution,high computational efficiency,and reliable convergence.展开更多
In the recovery process of the reusable rocket with vertical take-off and landing,it has to go through the active control process,such as power drop,hover and vertical landing.The key technology lies in the developmen...In the recovery process of the reusable rocket with vertical take-off and landing,it has to go through the active control process,such as power drop,hover and vertical landing.The key technology lies in the development of high-precision vertical recovery control algorithm.Therefore,a vertical take-off and landing reusable launch vehicle prototype is developed to verify the rationality of the flight control algorithm of rocket vertical recovery.The vertical take-off and landing reusable launch vehicle prototype is 0.45 m long,0.45 m wide,0.6 m high,and has 23 kg take-off weight with a maximum thrust of 400 N jet engine as the power plant,through four gas rudders to achieve the aircraft pitch and yaw and roll-on control.The prototype focuses on the verification of the guidance and control algorithm of the vertical recovery algorithm.Therefore,it is equipped with the vector control capability,avionics and measurement system similar to that of the vertical recovery rocket.The prototype can be used for verification of the flight control algorithm.展开更多
The skies over the Gobi Desert were the stage for a pivotal moment in China's space industry on December 3:the launch of the Zhuque-3,China's first reusable rocket.Developed by private firm LandSpace,the missi...The skies over the Gobi Desert were the stage for a pivotal moment in China's space industry on December 3:the launch of the Zhuque-3,China's first reusable rocket.Developed by private firm LandSpace,the mission was a milestone that could redefine the country's approach to spaceflight.展开更多
China's space program is moving forward quickly,thanks to a clear national strategy and a fast-growing commercial sector.What started as a careful,government-led project has become a lively mix of scientific resea...China's space program is moving forward quickly,thanks to a clear national strategy and a fast-growing commercial sector.What started as a careful,government-led project has become a lively mix of scientific research,new technology,affordable launch services and bold missions to other planets.With a permanent space station in low-Earth orbit,continuing missions to the moon and Mars,reusable rockets in the works and busy launch centers in Hainan and Gansu provinces,China is catching up in a field that used to be led by the United States.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51805131)Postdoctoral Research Foundation of China(Grant No.2018M640580)Fundamental Research Funds for the Central Universities(CN)Fundamental Research Funds for the Central Universities of China(Grant No.JZ2018HGBZ0155).
文摘There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing components.However,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting mode.For REBs,high rotational speed and long service life are two performance indexes that mutually restrict each other.To go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the REB.This review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of REBs.Then,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized comprehensively.These promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our team.Our more than ten years of relevant research on fluid-film and magnetic bearings are also introduced.This review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.
基金supported by National Natural Science Foundation of China(61425008,61333004,61273054)Top-Notch Young Talents Program of China,and Aeronautical Foundation of China(2015ZA51013)
基金co-supported by the National Natural Science Foundation of China(No.62103014)。
文摘An optimal feedback guidance law with disturbance rejection objective is proposed for endoatmospheric powered descent.This guidance law with an affine form is derived by solving a novel problem called Endoatmospheric Powered Descent Guidance with Disturbance Rejection(Endo-PDG-DR).The key idea of formulating the Endo-PDG-DR problem is dividing disturbances into two parts,modeled and unmodeled disturbances:the modeled disturbance is proactively exploited by augmenting it as a new state of a dynamics model;the unmodeled disturbance is reactively attenuated in terms of its effect on the guidance performance by adjoining a parameterized time-varying quadratic performance index in the proposed optimal guidance problem.A Pseudospectral Differential Dynamic Programming(PDDP)method is developed to solve the Endo-PDG-DR problem,and correspondingly a robust neighboring optimal state feedback law is obtained,which has two synergistic functionalities.One is adaptive optimal steering to accommodate the modeled disturbance,and the other is disturbance attenuation to compensate for the state perturbation effect induced by the unmodeled disturbance.Using the derived feedback guidance law,a disturbance rejection level is quantified,and is correspondingly optimized by designing a quadratic weighting parameter tuning law.The numerical computations of interest are performed within a pseudospectral setting,ensuring polynomial analytical solution,high computational efficiency,and reliable convergence.
文摘In the recovery process of the reusable rocket with vertical take-off and landing,it has to go through the active control process,such as power drop,hover and vertical landing.The key technology lies in the development of high-precision vertical recovery control algorithm.Therefore,a vertical take-off and landing reusable launch vehicle prototype is developed to verify the rationality of the flight control algorithm of rocket vertical recovery.The vertical take-off and landing reusable launch vehicle prototype is 0.45 m long,0.45 m wide,0.6 m high,and has 23 kg take-off weight with a maximum thrust of 400 N jet engine as the power plant,through four gas rudders to achieve the aircraft pitch and yaw and roll-on control.The prototype focuses on the verification of the guidance and control algorithm of the vertical recovery algorithm.Therefore,it is equipped with the vector control capability,avionics and measurement system similar to that of the vertical recovery rocket.The prototype can be used for verification of the flight control algorithm.
文摘The skies over the Gobi Desert were the stage for a pivotal moment in China's space industry on December 3:the launch of the Zhuque-3,China's first reusable rocket.Developed by private firm LandSpace,the mission was a milestone that could redefine the country's approach to spaceflight.
文摘China's space program is moving forward quickly,thanks to a clear national strategy and a fast-growing commercial sector.What started as a careful,government-led project has become a lively mix of scientific research,new technology,affordable launch services and bold missions to other planets.With a permanent space station in low-Earth orbit,continuing missions to the moon and Mars,reusable rockets in the works and busy launch centers in Hainan and Gansu provinces,China is catching up in a field that used to be led by the United States.
