Download or read book Model based Feedback Control of Subsonic Cavity Flows Control Design written by Xin Yuan and published by . This book was released on 2006 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this dissertation, we present and discuss development, implementation, and experimental results of reduced-order model based feedback control of subsonic cavity flows. Model based feedback control of subsonic flows have been studied and implemented by the flow control group at the Collaborative Center of Control Science (CCCS) at the Ohio State University (OSU). The team, composed of researchers from the departments of Electrical Engineering and Mechanical Engineering at the Ohio State, the Air Force Research Laboratory, and NASA Glenn Research Center, possesses synergistic capabilities in all of the required multidisciplinary areas of experimental data acquisition, computational flow simulation, low dimensional modeling, controller design, and experimental validation. The goal of the CCCS effort is to develop tools and methodologies for the use of closed-loop aerodynamic flow control to manipulate the flow over maneuvering air vehicles. The problem chosen for the initial study by the CCCS flow team is control of the resonant noise generated by subsonic flow past an open cavity. This phenomenon is characterized by a strong coupling between the flow dynamics and the flow-induced acoustic field that can lead to self-sustained resonance. Two approaches towards model development have been studied in this dissertation. One aims at representing the physical properties of the system by dynamical models in transfer function forms, referred to as the physics-based linear model in this dissertation. The other approach we have followed is based on proper orthogonal decomposition (POD) and Galerkin projection methods involving the flow governing equations, which is referred to as the nonlinear model or Galerkin model in the dissertation. Each model mentioned above can be further divided into two types: model derived from numerical simulation data and model derived from real time experimental data. Different types of feedback controllers have been designed for corresponding flow models. Closed-loop system performance has been evaluated by both numerical simulation and experimental implementation as well. These results confirm that model based feedback control represents a promising approach to flow control even in its current infancy state.
Download or read book Model based Feedback Control of Cavity Resonance written by Clarence W. Rowley and published by . This book was released on 2006 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents results of experiments and numerical simulations studying closed-loop feedback control of oscillations in the compressible flow past a rectangular cavity. When weapons bays are exposed to high flow speeds, extremely large pressure fluctuations result, and are often large enough to cause structural damage to the aircraft and internal stores. The goal of this work is to design an implement a model-based feedback controller to suppress oscillations in the flow past a cavity over a range of operating conditions, using much less power than open-loop techniques; and to understand the physics well enough to allow the techniques to be reliably transferred to full-scale aircraft. Several specific advances have been made in this work, relevant for cavity flow control as well as for other closed-loop flow control applications. Theoretical models are presented for temporally developing shear layers and cavity oscillations at the flow conditions used in both simulations and experiments. These models can be used to construct dynamic observers, which reconstruct the full flow information from a limited number of sensors, and significantly outperform static estimators such as Linear Stochastic Estimation (LSE).
Download or read book Active Flow Control written by Rudibert King and published by Springer Science & Business Media. This book was released on 2007-08-29 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains contributions presented at the Active Flow Control 2006 conference, held September 2006, at the Technische Universität Berlin, Germany. It contains a well balanced combination of theoretical and experimental state-of-the-art results of Active Flow Control. Coverage combines new developments in actuator technology, sensing, robust and optimal open- and closed-loop control and model reduction for control.
Download or read book Reduced Order Model Development for Feedback Control of Cavity Flows written by Edgar Javier Caraballo and published by . This book was released on 2008 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Controlling the flow over aerodynamic bodies has been a challenging problem for many years. Different open loop control techniques have been used in several flow configurations with some degree of success. However, in most cases the effectiveness of the controller is limited to the design conditions. In the present work, Proper Orthogonal Decomposition (POD) is used to derive low dimensional models of the subsonic flow over a cavity, in an effort to develop a feedback control system that can control the characteristic of the flow field. The Galerkin method is used as an additional tool to capture the time evolution of the flow field, reducing the problem into a system of ordinary differential. The stochastic estimation method is then used to link the variables that can be physically measured with those involved in the model. Particle Image Velocimetry (PIV) data and surface pressure measurement for the unforced flow (baseline) and for several open loop forcing conditions are used to derive the models. Three different approaches are investigated for control input separation. Different combinations of the flow condition are used in the model derivation to determine which forced flow should be used as a general case. A feedback controller is designed and tested experimentally for each model. The results showed that the variation in the experimental SPL spectra between the different models was negligible. However, a closer look at other factors hinted that the actuation mode separation method (M1) using the white noise forcing is the best choice. This method of separation does not require a clear identification of the control input region in the data. Also, it generates the best results in terms of reducing the tone and the OASPL while using a lower power input to achieve it. The white noise forcing helps to simplify the derivation process, as there is no need to pre-identify a specific forcing case. The multiple time estimation provides the best results in terms of the amplitude, but the implementation of this procedure is restricted by the hardware limitation.
Download or read book 1D and Multi D Modeling Techniques for IC Engine Simulation written by Angelo Onorati and published by SAE International. This book was released on 2020-04-06 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1D and Multi-D Modeling Techniques for IC Engine Simulation provides a description of the most significant and recent achievements in the field of 1D engine simulation models and coupled 1D-3D modeling techniques, including 0D combustion models, quasi-3D methods and some 3D model applications.
Download or read book An Experimental Investigation of Subsonic Cavity Flows Without and with Forcing written by Jesse Clayton Little and published by . This book was released on 2005 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Grazing flow over a shallow cavity is characterized by a shear layer instability feedback loop that induces strong pressure fluctuations at discrete frequencies. Examples include flow over aircraft weapons bays, aircraft landing gear openings and transmission or reception optical ports on aircraft. In the first application, this behavior can result in decreased accuracy of weapons delivery, fatigue failures and lowered efficiencies. Because of the variety of unwanted effects inherent to cavity flows, their control is of interest to both military and commercial aircraft applications. The complex nature of cavity flow has been explored since the mid-20th century with accelerated study over the past 25 years in hopes of understanding and controlling major pressure fluctuations within the cavity. A key to developing a successful control scheme for this fluidic system is a detailed understanding of the physics that govern the flow-acoustic coupling mechanisms. This work provides both qualitative and quantitative measurements for use in characterizing the fluid and acoustic physics that govern the resonance phenomenon. Focus is placed on the subsonic regime with an emphasis on Mach 0.30 flow and its control. Results include the analysis of surface pressure spectra and spatial correlations, flow visualization and velocity measurement using particle image velocimetry (PIV) in various controlled and baseline (unforced) cases. These results show that a well chosen actuation scheme at or near the receptivity region of the cavity shear layer can interrupt or weaken the acoustic feedback loop and significantly reduce the sound pressure level in the cavity. Physically, this amounts to modifying the development and evolution of the coherent structures spanning the cavity and thereby changing the frequency at which these vortices impact the trailing edge of the geometry. In addition, simultaneous dynamic surface pressure and planar velocity measurements are used in low dimensional modeling for closed-loop controller design purposes. Modeling using this method allows design of accurate models from experimental results rather than relying on numerical data, which is incapable of resolving the complex nonlinear production of acoustics in the low subsonic cavity flows at this time.
Download or read book Machine Learning Control Taming Nonlinear Dynamics and Turbulence written by Thomas Duriez and published by Springer. This book was released on 2016-11-02 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first textbook on a generally applicable control strategy for turbulence and other complex nonlinear systems. The approach of the book employs powerful methods of machine learning for optimal nonlinear control laws. This machine learning control (MLC) is motivated and detailed in Chapters 1 and 2. In Chapter 3, methods of linear control theory are reviewed. In Chapter 4, MLC is shown to reproduce known optimal control laws for linear dynamics (LQR, LQG). In Chapter 5, MLC detects and exploits a strongly nonlinear actuation mechanism of a low-dimensional dynamical system when linear control methods are shown to fail. Experimental control demonstrations from a laminar shear-layer to turbulent boundary-layers are reviewed in Chapter 6, followed by general good practices for experiments in Chapter 7. The book concludes with an outlook on the vast future applications of MLC in Chapter 8. Matlab codes are provided for easy reproducibility of the presented results. The book includes interviews with leading researchers in turbulence control (S. Bagheri, B. Batten, M. Glauser, D. Williams) and machine learning (M. Schoenauer) for a broader perspective. All chapters have exercises and supplemental videos will be available through YouTube.
Download or read book 05 5258 05 5393 written by and published by . This book was released on 2005 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Closed loop Control of Flow induced Cavity Oscillations written by Qi Song and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Flow-induced cavity oscillations are a coupled flow-acoustic problem in which the inherent closed-loop system dynamics can lead to large unsteady pressure levels in and around the cavity, resulting in both broadband noise and discrete tones. This problem exists in many practical environments, such as landing gear bays and weapon delivery systems on aircraft, and automobile sunroofs and windows. Researchers in both fluid dynamics and controls have been working on this problem for more than fifty years. This is because not only is the physical nature of this problem rich and complex, but also it has become a standard test bed for controller deign and implementation in flow control. The ultimate goal of this research is to minimize the cavity acoustic tones and the broadband noise level over a range of freestream Mach numbers. Although open-loop and closed-loop control methodologies have been explored extensively in recent years, there are still some issues that need to be studied further. For example, a low-order theoretical model suitable for controller design does not exist. Most recent flow-induced cavity models are based either on Rossiter's semi-expirical formula or a proper orthogonal decomposition (POD) based models. These models cannot be implemented in adaptive controller design directly. In addition, closed-loop control of high subsonic and supersonic flows remains an unexplored area.
Download or read book Numerical Simulation of Turbulent Flows and Noise Generation written by Christophe Brun and published by Springer Science & Business Media. This book was released on 2009-03-07 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large Eddy Simulation (LES) is a high-fidelity approach to the numerical simulation of turbulent flows. Recent developments have shown LES to be able to predict aerodynamic noise generation and propagation as well as the turbulent flow, by means of either a hybrid or a direct approach. This book is based on the results of two French/German research groups working on LES simulations in complex geometries and noise generation in turbulent flows. The results provide insights into modern prediction approaches for turbulent flows and noise generation mechanisms as well as their use for novel noise reduction concepts.
Download or read book 43rd AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2005 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2008 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cavity Unsteady Pressure Measurements at Subsonic and Transonic Speeds written by Maureen B. Tracy and published by . This book was released on 1997 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Simulation and Control of Cavity Flow Oscillations written by Clarence W. Rowley and published by . This book was released on 2002 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Control of Turbulent and Magnetohydrodynamic Channel Flows written by Rafael Vazquez and published by Springer Science & Business Media. This book was released on 2008 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph presents new constructive design methods for boundary stabilization and boundary estimation for several classes of benchmark problems in flow control, with potential applications to turbulence control, weather forecasting, and plasma control. One of the main features of the book is a unique "backstepping" approach to parabolic partial differential equations, which yields not only the stabilization of the flow, but also the explicit solvability of the closed-loop system. The work is an excellent reference for a broad, interdisciplinary engineering and mathematics audience: control theorists, fluid mechanicists, mechanical engineers, aerospace engineers, chemical engineers, electrical engineers, applied mathematicians, as well as research and graduate students in these fields.
Download or read book Aerospace America written by and published by . This book was released on 2004 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
