Feedback Control of Flow Separation Using Plasma Actuator and FBG Sensor

Abstract

A feedback control system for mitigating flow separation was developed by using a string-type dielectric-barrier-discharge (DBD) plasma actuator and a fiber Bragg grating (FBG) sensor. Tangential jets were induced from the string-type DBD plasma actuator, which was located at 5% chord from the leading edge of an NACA0024 airfoil. The FBG sensor was attached to the interior surface near the root of the cantilever beam modeled on the pressure surface of the airfoil. The strain at the cantilever root was reflected in the form of Bragg wavelengths (λB) detected by the FBG sensor when the cantilever tip was vibrated by the flow near the trailing edge of the airfoil. It was found that calculating running standard deviations in the Bragg wavelength (λB′) detected by the sensor was valuable for judging flow separation in real time. The feedback control of flow separation on the NACA0024 airfoil was successfully demonstrated by setting λB′=0.0028 with periodic flow separations generated in a wind tunnel by oscillating a side wall of the test section with frequency fw=0.42 Hz. It was confirmed that the appearance probability of flow separation tends to decrease with a decrease in the duration for calculating λB′ and with an increase in the duration of jet injection.

Effects of Jet Induced by String-type Plasma Actuator on Flow Around Three-Dimensional Bluff Body and Drag Force

“…If a groove for embedding a metal wire is structured on the surface of the test piece, it can be flush mounted to the objects. Using the string-type Pa, the suppression of turbine tip clearance flow and feedback control of flow separation on an NACA0015 airfoil have been presented by experiments [28,29]. These cases have verified the performance of the string-type Pa in flow control around a two-dimensional curved surface that has been reported by many researchers [8][9][10][11][12].…”

“…We consider that the mechanism underlying the drag increases by driving the string-type Pa is due to a decrease in pressure of the model back surface associated with the movement of the recirculation region. For the future works, 3D base flow around the 3D curved surface bluff body model under different flow conditions (e.g., Re and the angle of main stream) and multiple string-type Pas with different burst frequencies and the flow control with control laws [29,33] should be investigated.…”

Feasibility Study on Real-time Observation of Flow Velocity Field using Sparse Processing Particle Image Velocimetry

“…Hence, feedback control utilizing the real-time measurement of the flow state is expected to improve applicability. 2) Because of the complexity and nonlinearity of the flow phenomena, feedback control based on not the local flow information, but the full-state or global flow information clearly appears to be better for the future feedback control of flows.…”

Designs of Feedback Controllers for Fluid Flows Based On Model Predictive Control and Regression Analysis

“…However, closed-loop control, where the control action is determined based on information about a flow field from sensors, has recently been paid attention with the remarkable development of sensors and actuators. Although applications are still limited to relatively slow flows, the closed-loop control of fluid flows is actually realized in some experiments [4][5][6][7][8][9][10][11][12]. In general, the closed-loop control is expected to improve the regulation performance, robustness against the changes in the environment, and energy efficiency.…”

“…A wide variety of feedback control methods has been examined for fluid flows so far. For examples, there are heuristic methods based on experiments or simulation results [4][5][6][7][8]13], adaptive control [9][10][11][12], and linear optimal control [14][15][16][17]. In this paper, we focus on model predictive control (MPC), which is based on the nonlinear optimal control theory.…”