Author: Santosh Burnwal Publisher: LAP Lambert Academic Publishing ISBN: 9783848483853 Category : Languages : de Pages : 124
Book Description
Supercavitation is an emerging technology in which the most cursed 'Cavitation' is used as a beneficial to engineering application. Supercavitation is achieved when a body moves through water at sufficiently high speed, so that the fluid pressure drops to the water vapour pressure and a vapour bubble (called cavity) envelops the entire vehicle (except the cavitator and fins). Hence, the skin friction drag of the vehicle becomes almost zero. Hence, vehicle can move in the two phase medium.The development of supercavitating vehicle has been confronted with various challenging problems such as the potential instability of the vehicle, the unsteady nature of the cavity dynamics and the complex, non-linear and time delayed nature of the interaction between vehicle and cavity. Moreover depending upon some non dimensional parameter e.g. cavitation number ( ), the equilibrium of the vehicle may shift from a stable equilibrium to a limit cycle."
Author: I. N. Kirschner Publisher: ISBN: Category : Languages : en Pages : 39
Book Description
Supercavitating bodies can achieve very high speeds under water by virtue of reduced drag: with proper design, a cavitation bubble is generated at the nose and skin friction drag is drastically reduced. Depending on the type of supercavitating vehicle under consideration, the overall drag coefficient can be an order of magnitude less than that of a fully wetted vehicle. Slender-body theory and boundary element methods are two modern computational methods applied to the design of supercavitating vehicles. These course notes present recent advances in the theory behind these two computational approaches, as well as results and application of the methods to the simulation and control of supercavitating vehicles.
Author: Seong Sik Ahn Publisher: ISBN: Category : Cavitation Languages : en Pages :
Book Description
A supercavitating vehicle, a next-generation underwater vehicle capable of changing the paradigm of modern marine warfare, exploits supercavitation as a means to reduce drag and achieve extremely high submerged speeds. In supercavitating flows, a low-density gaseous cavity entirely envelops the vehicle and as a result the vehicle is in contact with liquid water only at its nose and partially over the afterbody. Hence, the vehicle experiences a substantially reduced skin drag and can achieve much higher speed than conventional vehicles. The development of a controllable and maneuvering supercavitating vehicle has been confronted with various challenging problems such as the potential instability of the vehicle, the unsteady nature of cavity dynamics, the complex and non-linear nature of the interaction between vehicle and cavity. Furthermore, major questions still need to be resolved regarding the basic configuration of the vehicle itself, including its control surfaces, the control system, and the cavity dynamics. In order to answer these fundamental questions, together with many similar ones, this dissertation develops an integrated simulation-based design tool to optimize the vehicle configuration subjected to operational design requirements, while predicting the complex coupled behavior of the vehicle for each design configuration. Particularly, this research attempts to include maneuvering flight as well as various operating trim conditions directly in the vehicle configurational optimization. This integrated approach provides significant improvement in performance in the preliminary design phase and indicates that trade-offs between various performance indexes are required due to their conflicting requirements. This dissertation also investigates trim conditions and dynamic characteristics of supercavitating vehicles through a full 6 DOF model. The influence of operating conditions, and cavity models and their memory effects on trim is analyzed and discussed. Unique characteristics are identified, e.g. the cavity memory effects introduce a favorable stabilizing effect by providing restoring fins and planing forces. Furthermore, this research investigates the flight envelope of a supercavitating vehicle, which is significantly different from that of a conventional vehicle due to different hydrodynamic coefficients as well as unique operational conditions.
Author: Publisher: ISBN: Category : Languages : en Pages : 34
Book Description
Recent progress in the development and application of homogenous multiphase CFD methods for large-scale gas cavities in liquid flows are presented. The focus of the presentation is on work in n-species transport approaches applied to developed and super-cavitation. Numerical formulation, physical modeling, and applications are included. Numerical issues to be discussed include: preconditioning in the context of incompressible through supersonic Mach numbers, arbitrary numbers of species, high density ratios, and large gas volume/mass fractions; computational grid requirements; dual-time formulation; and general large-scale high-performance computing. Physical modeling issues to be discussed include: homogeneous mixture compressibility; mass-transfer modeling; condensable and non-condensable gas species; turbulence modeling; and 6-degree-of-freedom 6DOF flowfield/rigid-body interaction. The applications to be presented range from naturally cavitating modeled flow on simple configurations (ogives, nozzles, airfoils/wedges) to more industrially relevant, complex-geometry applications including turbomachinery (cavitation breakdown), and super-cavitation (underwater rockets, hypervelocity darts, condensable and non-condensable cavities, gas-on/off transients, twin-vortex regime). Recent applications including Detached Eddy Simulation DES of natural cavities, and 6DOF analysis of a propelled notional super-cavitating vehicle are presented.
Author: Igor Nesteruk Publisher: Springer Science & Business Media ISBN: 3642236561 Category : Technology & Engineering Languages : en Pages : 236
Book Description
This collection is dedicated to the 70th jubilee of Yu. N. Savchenko, and presents experimental, theoretical, and numerical investigations written by an international group of well-known authors. The contributions solve very important problems of the high-speed hydrodynamics,such as supersonic motion in water, drag diminishing, dynamics and stability of supercavitating vehicles, water entry and hydrodynamic performances of hydrofoils, ventilated cavities after a disc and under the ship bottom. The book is written for researches, scientists, engineers, and students interested in problems of hydromechanics.
Author: Wego Wang Publisher: Springer Science & Business Media ISBN: 3319012738 Category : Technology & Engineering Languages : en Pages : 1041
Book Description
This book examines mechatronics and automatic control systems. The book covers important emerging topics in signal processing, control theory, sensors, mechanic manufacturing systems and automation. The book presents papers from the 2013 International Conference on Mechatronics and Automatic Control Systems in Hangzhou, held in China during August 10-11, 2013.
Author: Santosh Burnwal
Author: Anand K. Jammulamadaka
Author: I. N. Kirschner![An Integrated Approach to the Design of Supercavitating Underwater Vehicles [electronic Resource] PDF](https://books.google.com/books/content/images/frontcover/-a0OtAEACAAJ?fife=w80-h100)
Author: Seong Sik Ahn
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Author: David Escobar Sanabria
Author: Igor Nesteruk
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Author: Wego Wang