Elastically Mounted Double Aerodynamic Pendulum

Abstract

Elastically mounted double aerodynamic pendulum is an aeroelastic system with two rotational degrees of freedom. A wing is attached to the second link of the pendulum. It is shown that it is possible to select values of parameters in such a way as to make the trivial equilibrium (where both links of the pendulum are stretched along the flow) unstable. Numerical simulation of behavior of the system in such situations is performed, and arising limit cycles are studied. Experimental investigation of such aerodynamic pendulum is performed in the subsonic wind tunnel of the Institute of Mechanics of Lomonosov Moscow State University. Characteristics of periodic motions are registered for different values of parameters of the system. It is shown that experimental data are in qualitative agreement with results of numerical simulation.

Darrieus-Magnus Type Wind Turbine: Dynamics and Control

“…To determine the lateral force and the drag force acting on the Darrieus rotor, we use a quasi-static model (similar to [22][23][24][25][26][27]). We consider a separate Darrieus rotor rotating around its central axis C. Let the rotor be located in a uniform air flow, the velocity U of which is orthogonal to the rotor's axis of rotation.…”

Piezoaeroelastic system on the basis of a double aerodynamic pendulum

“…To describe the aerodynamic load on the pendulum, we will use the quasi‐steady model. Like in [22], we assume that the flow acts only upon the wing, and distributed aerodynamic forces applied to the wing can be reduced to the drag force and lift force applied in the mid‐point of the wing chord C , as well as to the moment about this point.…”

“…It was shown [22] that, for a two‐link aerodynamic pendulum in an elastic suspension (without any connection to electric circuit), this equilibrium position is unstable, if parameters of the system satisfy certain conditions.…”

“…It was shown [22] that if certain conditions are imposed upon parameters of the double aerodynamic pendulum in elastic mounting (without consideration of the structural damping) then there exists a range of values of the structural stiffness, where the trivial equilibrium is unstable; for values of stiffness lying outside this range, the equilibrium is asymptotically stable. In particular, the equilibrium is stable when the stiffness is zero.…”

“…Besides, consideration [21] of a double aerodynamic pendulum without springs in joints demonstrates that this system is also subject to flow-induced vibrations. In [22], conditions for the onset of oscillations are obtained based on analysis of dynamics of such pendulum in elastic mounting, and limit cycles arising in this system are studied experimentally and numerically. Thus, such system can also be considered as a possible working element of flow energy harvesters.…”