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Entropy measures for characterization of dynamic stall

Grant number: 16/06334-6
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): June 01, 2016
Effective date (End): May 31, 2017
Field of knowledge:Engineering - Aerospace Engineering - Aerospace Structures
Principal Investigator:Rui Marcos Grombone de Vasconcellos
Grantee:Antonio Elcio Ferreira Junior
Home Institution: Universidade Estadual Paulista (UNESP). Campus Experimental São João da Boa Vista. São João da Boa Vista , SP, Brazil

Abstract

Nonlinear problems in aeroelasticity have received recent attention from researchers, and the main reason is the increase in computational tools and nonlinear analysis techniques available. Among different sources of nonlinearities that compromise the aeroelastic response, separated flow on aerodynamic surfaces, caused by high angles of attack comprises one of the most important. The interaction of structural dynamics with nonlinear effects of separated flow leads to self-sustained oscillations at high angles of attack, resulting in a phenomenon known as dynamic stall, whose negative effects are well known in aeronautical industry, mainly in helicopters and wind turbine manufacturers. In this scenario, limit-cicle oscillations, quasi-periodicity and chaotic behavior may occur. The objective of this research is to analyze the nonlinear aeroelastic behavior from experimental data obtained from a model in a wind tunnel. This aeroelastic model corresponds to an airfoil, mounted on an elastic suspension that allows motion in pitch at high angles of attack. The experiments have been performed and the collected data will be used to extract informations that allows an indication of non-linear phenomena associated, characterizing the presence of dynamic stall effect on time series. Taking advantage of the progress and results achieved by the research group in the analysis of time series via state space reconstruction and Lyapunov exponents, this work proposes the use of entropy measures for categorization of nonlinear behavior.