Fundamentals and Applications of Modern Flow Control

Joslin, Ronald D.; Miller, R. J. Dwayne; Miller, Daniel N.

doi:10.2514/4.479892

Cited by 49 publications

(3 citation statements)

References 623 publications

(972 reference statements)

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“…In a wide sense, flow control is the manipulation of a fluid flow by passive or active means in order to achieve a beneficial result [1]. Flow control is a burgeoning field of fluid dynamics where modern control methodologies are applied to fluid systems to regulate, suppress, and control undesirable mechanisms that lead to flow instabilities that degrade performance.…”

Section: Introductionmentioning

confidence: 99%

Reduced-Order Models for Feedback Control of Transient Energy Growth

Kalur¹,

Hemati²

2018

2018 Flow Control Conference

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Feedback flow control is developed to suppress the transient energy growth of flow disturbances in a linearized channel flow. Specifically, we seek a controller that minimizes the maximum transient energy growth, which can be formulated as a linear matrix inequality problem. Solving linear matrix inequality problems can be computationally prohibitive for high-dimensional systems encountered in flow control applications. Thus, we develop reduced-order fluids models using balance truncation and proper orthogonal decomposition techniques. These models are designed to optimally approximate system energy while preserving the input-output dynamics that are essential for controller synthesis. Controllers developed based on these reduced-order models are found to reduce transient energy growth and to outperform linear quadratic controllers in the context of a linearized channel flow.

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Section: Introductionmentioning

confidence: 99%

Reduced-Order Models for Feedback Control of Transient Energy Growth

Kalur¹,

Hemati²

2018

2018 Flow Control Conference

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“…A reason for this is that closed-loop control requires much more sophisticated hardware and software than open-loop control. Another reason is that basic control theory deals with linear or linearized system dynamics to facilitate analytical treatment [3]. On the other hand, most fluid flows are inherently nonlinear and it is generally more convenient to manipulate flows using open-loop control.…”

Section: Flow Control Definitions and Preliminary Remarksmentioning

confidence: 99%

“…In the modern era, steady as well as unsteady suction and blowing are commonly employed in AFC [2]. During the last 2-3 decades, actuator technology has been progressing at a fast pace, as witnessed by the development of synthetic-jet and plasma actuators, which can be driven by fast electronic circuits [3][4][5]. The main advantage of these actuators is that they are zero-net-mass flux devices, i.e., they do not require fluid supply other than the ambient fluid of the exterior flow that is subject to AFC.…”

Section: Introductionmentioning

confidence: 99%

Active Control of Bluff-Body Flows Using Plasma Actuators

Konstantinidis

2019

Actuators

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Actuators play an important role in modern active flow control technology. Dielectric barrier discharge plasma can be used to induce localized velocity perturbations in air, so as to accomplish modifications to the global flow field. This paper presents a selective review of applications from the published literature with emphasis on interactions between plasma-induced perturbations and original unsteady fields of bluff-body flows. First, dielectric barrier discharge (DBD)-plasma actuator characteristics, and the local disturbance fields these actuators induce into the exterior flow, are described. Then, instabilities found in separated flows around bluff bodies that controlled actuation should target at are briefly presented. Key parameters for effective control are introduced using the nominally two-dimensional flow around a circular cylinder as a paradigm. The effects of the actuator configuration and location, amplitude and frequency of excitation, input waveform, as well as the phase difference between individual actuators are illustrated through examples classified based on symmetry properties. In general, symmetric excitation at frequencies higher than approximately five times the uncontrolled frequency of vortex shedding acts destructively on regular vortex shedding and can be safely employed for reducing the mean drag and lift fluctuations. Antisymmetric and symmetric excitation at low frequencies of the order of the natural frequency can amplify the wake instability and increase the mean and fluctuating aerodynamic forces, respectively, due to vortex locking-on to the excitation frequency or its subharmonics. Results from several studies show that the geometry and arrangement of the electrodes is of utmost significance. Power consumption is typically very low, but the electromechanical efficiency can be optimized by input waveform modulation.

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Trailing edge noise reduction of wind turbine blades by active flow control

et al. 2014

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In the current study, we investigate a route to reduction of the turbulent boundary layer–trailing edge interaction noise. The trailing edge noise is generated by surface pressure fluctuations beneath a turbulent boundary and scattered at the trailing edge of wind turbine blades. Trailing edge noise is considered to be the dominant noise source of modern wind turbines. Therefore, efforts are constantly made to attenuate the noise. Today, noise emission can be reduced by proper airfoil design or passive devices, such as trailing edge serrations. A further improved candidate technology for trailing edge noise attenuation is active flow control in the form of wall‐normal suction. With active flow control, the boundary layer features responsible for trailing edge noise generation can be manipulated, and correspondingly the trailing edge noise can be reduced. Detailed experimental investigations were performed at the Universities of Tel‐Aviv and Stuttgart. The tests showed that steady wall‐normal suction has a positive effect on the trailing edge noise by reducing the boundary layer thickness, and with it the integral length scales of the eddies within the boundary layer. Copyright © 2014 John Wiley & Sons, Ltd.

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Fundamentals and Applications of Modern Flow Control

Cited by 49 publications

References 623 publications

Reduced-Order Models for Feedback Control of Transient Energy Growth

Reduced-Order Models for Feedback Control of Transient Energy Growth

Active Control of Bluff-Body Flows Using Plasma Actuators

Trailing edge noise reduction of wind turbine blades by active flow control

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