However, much has happened since it went up, including the Blogger outage. Scroll down for a report on that. More new posts will be added below this one. The essay below is the conclusion of the ninth part in a series by Takuan Seiyo.
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Abstract The aim of this article is to analyze classical flutter and active control of single-cell thin-walled composite wind turbine blade beam based on piezoelectric actuation. Effects of piezoelectric actuation for classical flutter suppression on wind turbine blade beam subjected to combined transverse shear deformation, warping restraint effect, and secondary warping are investigated.
Active control is developed to enhance the vibrational behavior and dynamic response to classical aerodynamic excitation and stabilize structures that might be damaged in the absence of control.
Active optimal control scheme based on linear quadratic Gaussian LQG controller is implemented.
The research provides a way for rare study of classical flutter suppression and active control of wind turbine blade based on piezoelectric actuation.
Introduction Although instability of stall nonlinear flutter has generally been an important issue in flutter research [ 1 ], classical flutter was observed involving a high-speed rotating blade in pitch excitation process.
Simultaneously, with the advent of large wind turbine fitted with relatively slender blades, classical flutter may become a more important design consideration.
Most of the literature of classical flutter focused on the helicopter blades, noncoupling wing sections, and fan rotor blades [ 3 — 5 ]. As for active control, most of the literature focused on beam structures rather than the blade sectional shapes. Kapuria and Yasin [ 6 ] study the active vibration suppression of hybrid composite and fiber metal laminate plates integrated with piezoelectric fiber reinforced composite sensors and actuators.
Supersonic flutter control of a three-layered sandwich curved panel of rectangular plan form with an adaptive electrorheological fluid core layer is investigated by Hasheminejad and Motaaleghi [ 8 ]. Park and Kim [ 9 ] study the active twist rotor blade incorporating single crystal macrofiber composite actuators and analyze the aeroelasticity.
Although the rotor blade properties dynamically represent a real rotor blade, the analytical objects, are the torsional behavior of helicopter blades or the vibration behavior of airfoils in which only the torsional motions are involved. Simultaneously, the objects of the existing literature mostly concentrate on the frequency research rather than time response analysis.
In this work the classical flutter and flutter suppression of composite blade beam are investigated for single-cell thin-walled structure with piezoelectric patch embedded. The validity of the piezoelectric actuation is tested and illustrated by time domain response analysis rather than frequency research.
The analysis is applied to a laminated host structure of the circumferentially asymmetric stiffness CAS that produces bending-twist-transverse shear coupling. The governing system can be derived by the extended Hamilton principle. The net voltage output from sensor is fed to a controller for the purpose of actuation.
For piezoelectric actuation, active feedback control law and linear quadratic Gaussian controller are implemented. The purpose of present study is to investigate the validity of piezoelectric actuation under extreme conditions especially in critical region.
Analytical Model and Equations of Motion Consider the thin-walled structure in which piezoelectric patch is embedded as Figure 1.
The length of the blade is along direction. The origin of the rotating axis system is located at the rigid root in which the blade beam is mounted. It is assumed that. The equation of the middle line of the closed section is as follows [ 2 ]:Steam Turbine Flutter Analysis Blade flutter is a major concern for designers of steam turbines because it can lead to expensive blade failure.
The flutter risk can be assessed by calculating the logarithmic decrement (log-dec) of the aeroelastic modes due to aerodynamic damping. English Vocabulary Word List Alan Beale's Core Vocabulary Compiled from 3 Small ESL Dictionaries ( Words).
The thesis named ´Fluttering analysis in Wind Turbine Blade´ is worked mainly for the purpose of analyzing the fluttering behavior on blades of wind turbine by analyzing, structural analysis, modal analysis, Aeroelastic stability analysis, FSI.
The Impact of Blade Loading and Unsteady Pressure Bifurcations on Low-Pressure Turbine Flutter Boundaries. “ Experimental Investigation of Three-Dimensional Mechanisms in Low-Pressure Turbine Flutter,” Ph.D. thesis, KTH Royal Institute of Technology, Stockholm, Sweden.
The Impact of Blade Loading and Unsteady . blades that were translated in an oscillatory manner to model the vibration of turbine blades undergoing ﬂutter.
The aeroelasticity was modeled in the experiment by rotating the blade about a span-wise pivot, toward the hub of the apparatus.
The amplitude of the vibration was kept constant, as . Archives and past articles from the Philadelphia Inquirer, Philadelphia Daily News, and ph-vs.com