Aerothermoelastic Analysis And Control Of Airfoil In Supersonic Flow

As a common dynamic aeroelastic problem, airfoil flutter is self-excited vibrationphenomenon with the effects of airflow, thermal effection must be considered in airfoil flutteranysis in hypersonic flow. In this paper, thermal modal analysis and thermal flutter analysis of thecantilever plate airfoil model is presented, The flutter analysis and active flutter control of doubleedged airfoil is studied. The main progresses and contributions of the thesis are as follows:1. The airfoil is simplified as2-D cantilever airfoil plate model, the vibration equation ofairfoil is established. thermal modal of airfoil is analyzed with finite element method. Thermaleffection has little action on the dynamic behavior of airfoil. The natural frequency decreases withincreases of the aspect ratio2. The second-order piston theory is applied to calculate aerodynamic force and moment ofhypersonic airfoil model. The flutter equation of airfoil is established under the modal coordinate,V-g method is used for flutter analysis of airfoil. When the bend frequency and torsional frequencyoverlap occurs, the airfoil flutter phenomenon occurs. Rising of temperature makes the flutterspeed of the airfoil decreases.3. The third-order piston theory is applied to calculate unsteady aerodynamics.The dynamicequations of the double wedge airfoil is established. The differential equations are sloved by thefourth order Runge-Kutta method. The flutter characteristics of airfoil is obtained. The limit cyclephenomenon of the airfoil will happen in the flow with the critical Mach number.4. The motion equations of airfoil is established in SIMULINK. PID controller and fuzzy PIDcontroller are designed with changing control surface angle as input signal and hinge moment asoutput signal. Both controllers can effectively suppress the airfoil flutter. PID controller can raisethe critical Mach number from5.6to10. While fuzzy PID controller can improve the criticalMach number to11.2.