Rotor Head Vibration Absorber (RHVA) is a new kind of vibration reduc-tion device for helicoper, which provides some advantages in applications. The mechan-ical model for analysing and designing such kind of device is...Rotor Head Vibration Absorber (RHVA) is a new kind of vibration reduc-tion device for helicoper, which provides some advantages in applications. The mechan-ical model for analysing and designing such kind of device is presented, two analyticalmethods (in frequency domain and time domain) and its adaptabihty are studied. At thesame time the charactenstics of RHVA are analysed. The deduced rotor receptancesproved by model test are presented. At last the effectiveness of mechanical model andanalytical methods presented in this paper and of RHVA are illustrated in the calculation example.展开更多
A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to a...A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled （ first critical speed region 37% , second critical speed region 42% ）. To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.展开更多
In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming （SQP） method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on t...In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming （SQP） method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation （CST） method, and the C-topology body-fitted mesh is then automati- cally generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes （RANS） equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower-upper symmetric Gauss-Seidel （LU-SGS） is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart-Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the opti- mized airfoil under unsteady conditions are obviously weakened, and the dynamic stall character- istics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil.展开更多
The helicopter Trailing-Edge Flaps(TEFs)technology is one of the recent hot topics in morphing wing research.By employing controlled deflection,TEFs can effectively reduce the vibration level of helicopters.Thus,desig...The helicopter Trailing-Edge Flaps(TEFs)technology is one of the recent hot topics in morphing wing research.By employing controlled deflection,TEFs can effectively reduce the vibration level of helicopters.Thus,designing specific vibration reduction control methods for the helicopters equipped with trailing-edge flaps is of significant practical value.This paper studies the optimal control problem for helicopter-vibration systems with TEFs under the framework of adaptive dynamic programming combined with Reinforcement Learning(RL).Time-delay and disturbances,caused by complexity of helicopter dynamics,inevitably deteriorate the control performance of vibration reduction.To solve this problem,a zero-sum game formulation with a linear quadratic form for reducing vibration of helicopter systems is presented with a virtual predictor.In this context,an off-policy reinforcement learning algorithm is developed to determine the optimal control policy.The algorithm utilizes only vertical vibration load data to achieve a policy that reduces vibration,attains Nash equilibrium,and addresses disturbances while compensating for time-delay without knowledge of the dynamics of the helicopter system.The effectiveness of the proposed method is demonstrated in a virtual platform.展开更多
文摘Rotor Head Vibration Absorber (RHVA) is a new kind of vibration reduc-tion device for helicoper, which provides some advantages in applications. The mechan-ical model for analysing and designing such kind of device is presented, two analyticalmethods (in frequency domain and time domain) and its adaptabihty are studied. At thesame time the charactenstics of RHVA are analysed. The deduced rotor receptancesproved by model test are presented. At last the effectiveness of mechanical model andanalytical methods presented in this paper and of RHVA are illustrated in the calculation example.
基金Supported by the National Program on Key Basic Research Project(973Program)(2012CB026000)Ph.D Programs Foundation of Ministry of Education of China(20110010110009)
文摘A control system aims at vibration reduction in a two-span rotor system with two shear mode magnetorheological （MRF） dampers is designed. A finite element model of the MRF damper- rotor system is built and used to analyze the rotor vibration characteristics. Based on Hooke and Jeeves algorithm and the numerical simulation analysis, an optimal appropriate controller is proposed and designed. Experimental results show that rotor vibration caused by unbalance is well controlled （ first critical speed region 37% , second critical speed region 42% ）. To reflect advantages of optimi- zing strategy presented and validate the intelligent optimization control technology, detailed experi- ments were developed on a two-span rotor-vibration-control platform. The influence on accuracy, rapidity and stability of optimizing control for rotor vibration are analyzed. It provides a powerful technical support for the extension and application in target and control for shafting vibration.
基金the support of the National Natural Science Foundation of China (No. 11272150)
文摘In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming （SQP） method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation （CST） method, and the C-topology body-fitted mesh is then automati- cally generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes （RANS） equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower-upper symmetric Gauss-Seidel （LU-SGS） is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart-Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the opti- mized airfoil under unsteady conditions are obviously weakened, and the dynamic stall character- istics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil.
基金co-supported by the National Natural Science Foundation of China(Nos.62022060,62073234,62073158,62373268,62373273)the Basic Research Project of Education Department of Liaoning Province,China(No.LJKZ0401).
文摘The helicopter Trailing-Edge Flaps(TEFs)technology is one of the recent hot topics in morphing wing research.By employing controlled deflection,TEFs can effectively reduce the vibration level of helicopters.Thus,designing specific vibration reduction control methods for the helicopters equipped with trailing-edge flaps is of significant practical value.This paper studies the optimal control problem for helicopter-vibration systems with TEFs under the framework of adaptive dynamic programming combined with Reinforcement Learning(RL).Time-delay and disturbances,caused by complexity of helicopter dynamics,inevitably deteriorate the control performance of vibration reduction.To solve this problem,a zero-sum game formulation with a linear quadratic form for reducing vibration of helicopter systems is presented with a virtual predictor.In this context,an off-policy reinforcement learning algorithm is developed to determine the optimal control policy.The algorithm utilizes only vertical vibration load data to achieve a policy that reduces vibration,attains Nash equilibrium,and addresses disturbances while compensating for time-delay without knowledge of the dynamics of the helicopter system.The effectiveness of the proposed method is demonstrated in a virtual platform.
