Research On Vibratory Load Control Of Smart Rotor With Trailing Edge Flaps

Vibration of helicopter is quite severe due to its complex working environment.A smart rotor with trailing edge flaps is an efficient kind of active vibration control method,which controls the vibratory load by adjusting the aerodynamic force distribution and the blade response through the deflection of flaps equipped at the outer side of blades.The aeroelastic model of rotor with trailing edge flaps is built.A high accuracy structural dynamic model and aerodynamic model for rotor system with trailing edge flaps are established and validated.In addition,an optimization method is employed to study the rotor vibration control effect of trailing edge flaps.First of all,the dynamic model for rotors with trailing edge flaps is investigated.The natural frequency and transient response of blades are calculated to verify the current model.A set of coordinate systems is developed to describe the complex movement and deformation of blades and trailing edge flaps.Both the rigid movement and elastic deformation of blades are considered during deriving the formulas for kinetic energy of blades and flaps.To derive the expression of blade strain energy,the nonlinear relationship between elastic deformation and the strain is exactly described based on the finite strain.The work of airload done to the rotor system is also derived.Based on the Hamilton's principle,the dynamic equations for rotor with trailing edge flaps are derived.An accurate aerodynamic model for rotor airload calculation is built,which contains two main parts: rotor wake prediction and unsteady airload calculation.A viscous vortex particle method is established to predict the steady wake of rotor.The induced velocity at rotor disk is calculated with the verticity distribution based on the Biot-Savert theorem.For airfoil aerodynamic force calculation,the structural gird is generated for a flapped airfoil,and a computational fluid dynamic method is introduced to gain the airfoil aerodynamic force.A radial based function is used to build a surrogate model for the computational fluid dynamic method,which is time saving and accurate for aeroelastic iteration.Studies on aeroelasticity of rotor with trailing edge flaps are carried out based on the structural dynamic model and the aerodynamic model.The procedure of aerelastic analysis and vibratory load calculation is introduced before investigating the influences of trailing edge flaps on rotor aeroelastic response.Furthermore,an optimization method with inequality constraints is raised based on the aeroelastic model for rotor with trailing edge flaps.A variable metric interative algorithm is introduced to solve the optimization problem and predict the optimized control law for trailing edge flaps.In the case of lacking in deflection ability,the effect of vibration control is discussed.The relation between blade torsion and vibration reduction effect of trailing edge flaps is also discussed.The influence research of the design parameters of trailing edge flap is carried out.At last,a modal test of the blade is performed to validate the change of natural frequencies before and after the installation of drive device of trailing edge flap.A wind tunnel test of blade with trailing edge flap is designed and completed.During the wind tunnel test,the influence of magnitude and frequency of input signals as well as the wind velocity on the performance of drive device is studied.By conducting a phase sweep test,the feasibility of structural vibratory load control with trailing edge flap is verified.