The Panel Flutter And Its Suppression In The Supersonic Flow

Panel flutter is a kind of self-excited oscillation resulting from the interactionof the inertial force, elastic force of the panel and the aerodynamic loads when thepanel is exposed to the supersonic flow. The flutter can cause the panel to vibratelaterally with high amplitude, which may lead to the fatigue failure of the flightvehicle. The growth of the temperature induced by the aerodynamic heating effectduring the flight may introduce in-plane thermal forces and bending moments to thepanel, which will decrease the bending stiffness of the panel. In addition, theaerodynamic noise caused by the engine of the fight vehicle and the supersonic flowis harmful to the fatigue life of the panel. In order to minish the damages caused bythe panel flutter, different passive and active control methods are adopted in theliteratures to enhance the critical flutter dynamic pressure or reduce the flutteramplitude of the panel. Thus, the present study devotes to investigate the panelflutter in the following aspects:The von Karman nonlinear displacement-strain relationship and the third orderpiston theory are employed to describ the geometry and aerodynamic nonlinearities,respectively. The Hamilton principle is adopted to establish the equation of motionof the panel in the supersonic flow. The Galerkin discrete method is used to truncatethe partial differential equation of motion of the panel into a set of ordinarydifferential equations, which are then simulated by the fourth order Runge-Kuttamethod. The nonlinear dynamic theory is adopted to solve the critical flutterdynamic pressure of the panel and explain the frequencies superpositionphenomenon in the engineering. Then effect of the linear damping term on thecritical flutter dynamic pressure, the natural frequencies and the vibrationfrequencies are discussed, respectively.A passive control strategy is adopted to suppress the flutter of the panelaccording to a stiffened scheme, and the dynamic response of the stiffened panel inthe supersonic is investigated. In order to save the computational expense, thetransitional finite element method is abandoned in the modeling procedure. Thestiffened panel system is equivalent to a panel subsystem and a stiffener subsystemon the basis of two reasonable assumptions. The matching condition of the force andthe displacement is satisfied at the interface between the two subsystems. TheHamilton principle is adopted to establish the model of the panel subsystem, and theEuler-Bernoulli beam theory is adopted to establish the model of the stiffenersubsystem. On the basis of deformation compatibility, the acting and reacting forcesbetween the panel and the stiffener are deduced, and then the partial differential governing equation of motion of the stiffened panel is obtained. The Galerkinmethod is employed in the discrete process, and then a new method is established toanalysis the flutter of the stiffened panel based on the Galerkin method. Then theeffects of the height and width of the stiffener and the stiffened scheme on the effectof the flutter suppression of the panel are investigated, respectively.A passive control strategy is adopted to suppress the flutter of the panel byinstalling a set of dynamic absorber on the backside of the panel. The couplinginduction between the dynamic absorber and the panel is considered in the modelingprocedure, and the acting and reacting forces between the dynamic absorber and thepanel are described as the function of their relative displacement and velocity. TheHamilton principle and Newton’s Second law of motion are used to establish themodels of the panel and the dynamic absorber, respectively. Based on the interactionforces between the dynamic absorber and the panel, the combined equations ofmotion of the panel-absorber system are obtained. The effects of the mass, stiffness,damping and installation position on the flutter suppression of the panel arediscussed, respectively. At last, the installation position of the absorber is optimizedon the basis of the influence law of the dynamic absorber on the flutter superpositionfrequency of the panel.The flutter of the panel under thermal-acoustic combined excitation isinvestigated. The thermal strain induced by the temperature is introduced into thegeometry relationship of the panel, and the acoustic excitation is assumed as astationary white-Gaussian random pressure with zero mean, the Hamilton principleis employed to establish the equation of motion of the panel. The effects of the fiberangle, temperature difference and the SPL on the flutter of the panel are investigated,respectively. Then the dynamic response of the panel under the thermal-acousticcombined excitation is simulated.