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Category :
Languages : en
Pages :
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Acoustoelasticity is the study of the dynamic interaction between elastic structures and acoustic enclosures. In this dissertation, acoustoelasticity is considered in the context of liquid rocket engine design. The techniques presented here can be used to determine which forcing frequencies are important in acoustoelastic systems. With a knowledge of these frequencies, an analyst can either find ways to attenuate the excitation at these frequencies or alter the system in such a way that the prescribed excitations do result in a resonant condition. The end result is a structural component that is less susceptible to failure. The research scope is divided into three parts. In the first part, the dynamics of cylindrical shells submerged in liquid hydrogen (LH2) and liquid oxygen (LOX) are considered. The shells are bounded by rigid outer cylinders. This configuration gives rise to two fluid-filled cavities: an inner cylindrical cavity and an outer annular cavity. Such geometries are common in rocket engine design. The natural frequencies and modes of the fluid-structure system are computed by combining the rigid wall acoustic cavity modes and the in vacuo structural modes into a system of coupled ordinary differential equations. Eigenvalue veering is observed near the intersections of the curves representing natural frequencies of the rigid wall acoustic and the in vacuo structural modes. In the case of a shell submerged in LH2, system frequencies near these intersections are as much as 30% lower than the corresponding in vacuo structural frequencies. Due to its high density, the frequency reductions in the presence of LOX are even more dramatic. The forced responses of a shell submerged in LH2 and LOX while subject to a harmonic point excitation are also presented. The responses in the presence of fluid are found to be quite distinct from those of the structure in vacuo . In the second part, coupled m.
Author:
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Category :
Languages : en
Pages :
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Book Description
Acoustoelasticity is the study of the dynamic interaction between elastic structures and acoustic enclosures. In this dissertation, acoustoelasticity is considered in the context of liquid rocket engine design. The techniques presented here can be used to determine which forcing frequencies are important in acoustoelastic systems. With a knowledge of these frequencies, an analyst can either find ways to attenuate the excitation at these frequencies or alter the system in such a way that the prescribed excitations do result in a resonant condition. The end result is a structural component that is less susceptible to failure. The research scope is divided into three parts. In the first part, the dynamics of cylindrical shells submerged in liquid hydrogen (LH2) and liquid oxygen (LOX) are considered. The shells are bounded by rigid outer cylinders. This configuration gives rise to two fluid-filled cavities: an inner cylindrical cavity and an outer annular cavity. Such geometries are common in rocket engine design. The natural frequencies and modes of the fluid-structure system are computed by combining the rigid wall acoustic cavity modes and the in vacuo structural modes into a system of coupled ordinary differential equations. Eigenvalue veering is observed near the intersections of the curves representing natural frequencies of the rigid wall acoustic and the in vacuo structural modes. In the case of a shell submerged in LH2, system frequencies near these intersections are as much as 30% lower than the corresponding in vacuo structural frequencies. Due to its high density, the frequency reductions in the presence of LOX are even more dramatic. The forced responses of a shell submerged in LH2 and LOX while subject to a harmonic point excitation are also presented. The responses in the presence of fluid are found to be quite distinct from those of the structure in vacuo . In the second part, coupled m.
Author: Robert Benjamin Davis
Publisher:
ISBN:
Category : Aeroelasticity
Languages : en
Pages :
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Book Description
Acoustoelasticity is the study of the dynamic interaction between elastic structures and acoustic enclosures. In this dissertation, acoustoelasticity is considered in the context of liquid rocket engine design. The techniques presented here can be used to determine which forcing frequencies are important in acoustoelastic systems. With a knowledge of these frequencies, an analyst can either find ways to attenuate the excitation at these frequencies or alter the system in such a way that the prescribed excitations do result in a resonant condition. The end result is a structural component that is less susceptible to failure. The research scope is divided into three parts. In the first part, the dynamics of cylindrical shells submerged in liquid hydrogen (LH2) and liquid oxygen (LOX) are considered. The shells are bounded by rigid outer cylinders. This configuration gives rise to two fluid-filled cavities: an inner cylindrical cavity and an outer annular cavity. Such geometries are common in rocket engine design. The natural frequencies and modes of the fluid-structure system are computed by combining the rigid wall acoustic cavity modes and the in vacuo structural modes into a system of coupled ordinary differential equations. Eigenvalue veering is observed near the intersections of the curves representing natural frequencies of the rigid wall acoustic and the in vacuo structural modes. In the case of a shell submerged in LH2, system frequencies near these intersections are as much as 30% lower than the corresponding in vacuo structural frequencies. Due to its high density, the frequency reductions in the presence of LOX are even more dramatic. The forced responses of a shell submerged in LH2 and LOX while subject to a harmonic point excitation are also presented. The responses in the presence of fluid are found to be quite distinct from those of the structure in vacuo. In the second part, coupled mode theory is used to explore the fundamental features of acoustoelastic systems. The result is the development of relatively simple techniques that allow analysts to make informed decisions concerning the importance of acoustic-structure coupling without resorting to more time consuming and complex methods. In this part, a new nondimensional parameter is derived to quantify the fundamental strength of a particular acoustic-structure interaction irrespective of material and fluid properties or cavity size. It is be shown that, in some cases, reasonable approximations of the coupled acoustic-structure frequencies can be calculated without explicit knowledge of the uncoupled component mode shapes. Monte Carlo simulations are performed to determine the parameter values over which the approximate coupled frequency expressions are accurate. General observations concerning the forced response of acoustoelastic systems are then made by investigating the response of a simplified two mode system. The third part of this research discusses the implementation of a component mode synthesis (CMS) technique for use with geometrically complex acoustoelastic systems. The feasibility of conceptually similar techniques was first demonstrated over 30 years ago. Since that time there have been remarkable advancements in computational methods. It is therefore reasonable to question the extent to which CMS remains a computationally advantageous approach for acoustoelastic systems of practical interest. This work demonstrates that relative to the most recent release of the popular finite element software package, ANSYS, CMS techniques have a significant computational advantage when the forced response of an acoustoelastic system is of interest. However, recent improvements to the unsymmetric eigensolver available in ANSYS have rendered CMS a less efficient option when calculating system frequencies and modes. The CMS technique is then used to generate new results related to geometrically complex acoustoelastic systems.
Author: Andrew M. Brown
Publisher: Springer Nature
ISBN: 3031182073
Category : Technology & Engineering
Languages : en
Pages : 177
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Book Description
This is the first Structural Dynamics book focused on this indispensable aspect of liquid rocket engine design. This book begins by reviewing basic concepts in Structural Dynamics, including the free and forced response of SDOF and MDOF systems, along with some discussion of how numerical solutions are generated. The book then moves to a discussion of specific applications of these techniques in LREs, progressing from component level (turbomachinery and combustion devices), up through engine system models, and finally to integration with a launch vehicle. Clarifies specific topics including the Campbell and SAFE Diagrams for resonance identification in turbomachinery, the complications of component analysis in the pump side due to a host of complication factors such as acoustic/structure interaction, the "side-loads" fluid/structure interaction problem in overexpanded rocket nozzles, and competing methods for generation overall engine system interface loads. Includes specific examples for illustration while closing with rotordynamic analysis, dynamic data analysis, and vibroacoustics.
Author: R. Ebrahimi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Arun K. Saha
Publisher: Springer
ISBN: 8132227433
Category : Technology & Engineering
Languages : en
Pages : 1638
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This volume comprises the proceedings of the 42nd National and 5th International Conference on Fluid Mechanics and Fluid Power held at IIT Kanpur in December, 2014.The conference proceedings encapsulate the best deliberations held during the conference. The diversity of participation in the conference, from academia, industry and research laboratories reflects in the articles appearing in the volume. This contributed volume has articles from authors who have participated in the conference on thematic areas such as Fundamental Issues and Perspectives in Fluid Mechanics; Measurement Techniques and Instrumentation; Computational Fluid Dynamics; Instability, Transition and Turbulence; Turbomachinery; Multiphase Flows; Fluid‐Structure Interaction and Flow‐Induced Noise; Microfluidics; Bio‐inspired Fluid Mechanics; Internal Combustion Engines and Gas Turbines; and Specialized Topics. The contents of this volume will prove useful to researchers from industry and academia alike.
Author: Andreas Linderholt
Publisher: Springer
ISBN: 3319746545
Category : Science
Languages : en
Pages : 215
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Book Description
Dynamics of Coupled Structures, Volume 4: Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics, 2018, the fourth volume of nine from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of the Dynamics of Coupled Structures, including papers on: Experimental Nonlinear Dynamics Joints, Friction & Damping Nonlinear Substructuring Transfer Path Analysis and Source Characterization Analytical Substructuring & Numerical Reduction Techniques Real Time Substructuring Assembling & Decoupling Substructures & Boundary Conditions
Author: Dario Di Maio
Publisher: Springer
ISBN: 3319746936
Category : Technology & Engineering
Languages : en
Pages : 239
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Book Description
Rotating Machinery, Vibro-Acoustics & Laser Vibrometry, Volume 7: Proceedings of the 36th IMAC, A Conference and Exposition on Structural Dynamics, 2018, the seveth volume of nine from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Rotating Machinery, Hybrid Testing, Vibro-Acoustics & Laser Vibrometry, including papers on: Rotating Machinery Vibro-Acoustics Experimental Techniques Scanning Laser Doppler Vibrometry Methods
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Author: Michelle Otero
Publisher:
ISBN:
Category :
Languages : en
Pages : 29
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Book Description
Acoustic instabilities remain a key design concern faced in the development of liquid rocket engines. The interaction between the acoustic modes and the occurring combustion reactions can be detrimental to the engine. The fluctuating pressure waves resulting from the flame oscillations in the system can potentially lead to engine failure. For this reason, research in acoustic instabilities and methods to minimize the influences on the engine, has maintain interest in the aerospace community. The scope of this study was to design, optimize and characterize acoustic behaviors of a scaled rocket combustion chamber simulating acoustic pressure waves. Tangential and longitudinal acoustic waves of the system were extracted and validated through analytical and computational fluids dynamics models. The results of this study will assist with the process of extracting dominant oscillation frequencies of a system essential in the design of acoustic suppression devices for attenuation of critical frequencies.
Author: R. C. Potter
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 188
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