Proceedings ArticleDOI
Frequency-domain based feedback control of flow separation using synthetic jets
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TLDR
In this article, the NARMAX (Nonlinear Auto Regressive Moving Average with eXogenous inputs) system identification method is applied to develop a nonlinear flow model and low-pass filtering is introduced as an effective method to facilitate a quasi-linear approximation of the nonlinear fluidic system including synthetic jet actuation in the frequency domain.Abstract:
This research aims to facilitate feedback control of flow separation using synthetic jets. The effects of synthetic jets on flow separation are assessed via CFD simulations on a rounded backward-facing step. The NARMAX (Nonlinear Auto Regressive Moving Average with eXogenous inputs) system identification method is applied to develop a nonlinear flow model. Low-pass filtering is introduced as an effective method to facilitate a quasi-linear approximation of the nonlinear fluidic system including synthetic jet actuation in the frequency domain. Employing the describing function method, the approximate frequency response of the system is analyzed and implemented for the synthesis of a linear feedback controller. Finally, a PI controller is demonstrated to achieve tracking of a desired pressure with an improvement in the transient response over the open loop system.read more
Citations
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Feedback control for form-drag reduction on a bluff body with a blunt trailing edge
TL;DR: In this article, a linear feedback control is proposed to increase the base pressure on a backward-facing step via feedback control, to be ultimately translated to a drag reduction on a blunt-based bluff body.
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Robust flow control and optimal sensor placement using deep reinforcement learning
TL;DR: In this paper, a closed-loop strategy was proposed to reduce the drag of a cylinder in laminar flow conditions. But the authors focused on the efficiency and robustness of the identified control strategy and introduced a novel algorithm (S-PPO-CMA) to optimise the sensor layout.
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Robust flow control and optimal sensor placement using deep reinforcement learning
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NARX modelling of unsteady separation control
TL;DR: In this paper, a nonlinear auto-regressive with eXogenous input (NARX) model is used to model the flow behavior in response to a periodic forcing.
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NARMAX Identification Based Closed-Loop Control of Flow Separation over NACA 0015 Airfoil
TL;DR: A closed-loop control algorithm for the reduction of turbulent flow separation over NACA 0015 airfoil equipped with leading-edge synthetic jet actuators (SJAs) is presented.
References
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Boundary layer theory
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
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Applied Nonlinear Control
TL;DR: Covers in a progressive fashion a number of analysis tools and design techniques directly applicable to nonlinear control problems in high performance systems (in aerospace, robotics and automotive areas).
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Spectral/hp Element Methods for Computational Fluid Dynamics
TL;DR: In this article, Jacobi polynomials Gauss-type integration Collocation differentiation Co discontinuous expansion bases are used to simulate incompressible flows in one-dimensional expansion bases.
Journal ArticleDOI
Oscillatory Control of Separation at High Reynolds Numbers
Avi Seifert,LaTunia G. Pack +1 more
TL;DR: In this paper, an experiment conducted in a pressurized, cryogenic wind tunnel demonstrates that unsteady flow control using oscillatory blowing (with essentially zero mass flux) can effectively delay flow separation and reattach separated flow on an airfoil at chord Reynolds numbers as high as 38 × 10 6.
Journal ArticleDOI
Aspects of low- and high-frequency actuation for aerodynamic flow control
TL;DR: In this paper, a Coanda-like deflection of the forced separating shear layer toward the surface is proposed for aerodynamic control of separated flows over aerodynamic (or bluff) bodies in which the separated flow domain scales with the characteristic length of the body.