Dissertation/Thesis Abstract

Design of Closed-Loop Controller for Active Control of Flow over Flapped Airfoil
by Obeid, Sohaib A. M., Ph.D., Clarkson University, 2020, 265; 28089648
Abstract (Summary)

The aim of this study is to develop closed-loop feedback control algorithms for turbulent flow separation phenomena over 2-D flapped airfoil equipped with set of synthetic jet actuators (SJAs). The SJA was mounted in the main body of the airfoil near to the leading edge (0.1c) with an inclined injecting orifice flow injection at 30 degrees to the airfoil wall tangent. The control objective is to delay flow separation or stall by actuating the SJA through a closed-loop control algorithm using surface pressures as sensor data. FLUENT simulation results are validated by wind tunnel test data of turbulent flow over a NACA 0015 airfoil at Re=1x106 . The synthetic jet excitation was modeled by a sinusoidal velocity boundary condition. The effect of synthetic jets in improving the aerodynamic performance of the airfoil by significantly modifying the surface pressure distribution was carefully analyzed. Together with their critical roles, the influences of the actuation frequency (fj), and momentum coefficient ratio, (Cu), in the performance of the synthetic jets on separation control, were evaluated. A control system design approach based on system identification using NARMAX is investigated. A NARMAX model of the flow is constructed using data from a pressure sensor which includes nonlinearities in the flow excited by synthetic jets. A synthetic jet actuator model is employed and controller design follows the standard PI algorithm for both single-input single-output and multiple-input single-output systems. The response of the resulting closed loop feedback control system (comprised of PI controller, SJA model and NARMAX model) is shown to track the desired pressure command. A significant improvement in the transient response over the open-loop system at high angles of attack is realized. The benefits of closed-loop control versus open-loop control are thoroughly investigated. Parametric studies for the effect of velocity profile configuration of synthetic jets on airfoil aerodynamic performance parameters, and effect of synthetic jets frequency upon stability and robustness of the proposed controller are also included in this dissertation. To furnish a basis for model based closed-loop controller design, the Dynamic Mode Decomposition (DMD) mathematical algorithms (Exact DMD method) as well as, the algorithm for conventional Proper Orthogonal Decomposition (POD) were studied and used to develop reduced order models for the flow dynamics. The modeling approaches studied and the control design methods reported in this work will be used for wind tunnel testing in future. 

Indexing (document details)
Advisor: Ahmadi, Goodarz, Jha, Ratneshwar
Commitee: Helenbrook, Brian, Bohl, Douglas G., Budisic, Marko
School: Clarkson University
Department: Mechanical Engineering
School Location: United States -- New York
Source: DAI-B 82/3(E), Dissertation Abstracts International
Subjects: Mechanical engineering, Aerospace engineering, Engineering
Keywords: Control, Feedback, Flow separation, NARMAX, POD, Synthetic jets
Publication Number: 28089648
ISBN: 9798664799507
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