Download or read book A Detailed Study of the Flowfield of a Submarine Propeller During a Crashback Maneuver written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extensive study of crashback was performed in the U.S. Navy's William B. Morgan Large Cavitation Channel (LCC), located in Memphis, TN. Propeller 4381 was attached to a standard axisymmetric submarine hull model (DTMB Model 5495-3) which was then suspended in the LCC. Forces and moments were measured on both the body and the propeller for steady and unsteady crashback conditions. The unsteady conditions were simulated by allowing the propeller to "windmill" in the forward direction and then engaging the propeller in the reverse direction, with the tunnel velocity held constant. Forces and moments were measured during the change in propeller speed. A further simulation was undertaken whereby the tunnel motor was shut off once the windmilling propeller engaged in reverse rotation and the tunnel speed was allowed to coast down to zero. Forces and moments were measured during this simulation also. Laser Doppler velocimeter (LDV) measurements of the flow field around the propeller during steady crashback were obtained in addition to extensive flow visualization measurements. The dimensionless force and moment data were found to collapse when plotted against the ratio of the actual propeller speed to the propeller speed required for self propulsion in forward motion. The force and moment coefficients were found to have a local maximum when this ratio was around -0.8. Unsteady crashback maneuvers also were investigated with two different types of simulations in which the propeller and tunnel speeds were allowed to vary. In some cases the peak off-axis force and moment coefficient magnitudes exceeded those observed during the steady crashback measurements. The LDV studies showed that the ring vortex structure appeared to migrate upstream and outward as the reverse propeller speed increased in magnitude. (145 figures, 17 refs.).
Download or read book Flow Regimes and Instabilities of Propeller Crashback written by Matthew Pontarelli and published by . This book was released on 2017 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crashback operation of a propeller is a common emergency slowing maneuver for ships and submarines. The reversing of the propeller while the vessel is moving forward results in large loads on the propeller blades and highly detached flow, which presents both practical concerns and fundamental fluid physics inquiries. This thesis contains a comprehensive numerical analysis of two propellers in crashback operation. Available numerical and experimental data for David Taylor Model Basin (DTMB) 4381 propeller are used for validation of the computational fluid dynamics solver used, REX. A second propeller, Maritime Research Institute Netherlands (MARIN) 7371R is used to classify the common crashback flow behavior into regimes. Four regimes were identified, each existing for a range of operating conditions. The most prominent and deciding feature of the flow regimes is the presence of a ring vortex, resulting from the opposing action of the free-stream flow and the propeller induced flow. The position, shape and strength changes between regimes, dominating the dynamics of the flow by altering the induced flow into the propeller disk. Flow conditions resulting from regime transitions are described. Changes in the ring vortex structure lead to two stable flow conditions of interest. One condition produces a reduction of thrust despite the increase in flow speed into the propeller and negligible side-forces. The other condition creates large side-forces capable of rotating a vessel, resulting from an asymmetry forming in the ring vortex. Additionally, massive flow separation occurs at high free-stream speeds that cause extreme blade loading. An extensive description of each flow regime is provided, with further investigation and discussion of the flow regimes that present more practical concerns and novel characteristics of the crashback flow.
Download or read book A Detailed Study of the Flow Field of a Submarine at Large Angle of Drift written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: When a submarine executes a high-speed turn, the sail experiences a cross-flow velocity component. Because the sail is essentially a low-aspect-ratio finite-span wing, it sheds a tip vortex. The flow field induced by the vortex causes higher pressures on the hull deck and lower pressures on the keel, creating a net downward force that leads to an uncommanded nose-up pitching moment. Tests to examine the features of such flows were conducted in the U.S. Navy's Large Cavitation Channel (LCC) in Memphis, TN. A submarine model of length 22.7 ft was mounted in the LCC at angles of drift of 0, 5, and 9.5 degrees and was tested with the sail on and off. Tests were conducted at speeds up to 14.9 m/s (27-kts). Circumferential pressure distributions and laser Doppler velocimeter (LDV) surveys were obtained at two axial locations for each of the speeds and configurations tested. Body forces and moments were also measured using a 6-component force balance. The pressure distributions were integrated to obtain section vertical force coefficients, and the velocity data obtained from the LDV measurements were used to estimate the circulation of the tip vortex. The measured pressure distributions were consistent with the hypothesized mechanism by which the tip vortex changed the flow around the submarine and created the nose-up pitching moment. The measured pitching moment and the sectional vertical force coefficients demonstrated the nonlinear variation with angle of drift predicted by theory. The measured values of the circulation were in general agreement with values obtained by other researchers, although the measured circulation values were consistently somewhat higher.
Download or read book Twenty Second Symposium on Naval Hydrodynamics written by National Research Council and published by National Academies Press. This book was released on 2000-03-02 with total page 1039 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Twenty-Second Symposium on Naval Hydrodynamics was held in Washington, D.C., from August 9-14, 1998. It coincided with the 100th anniversary of the David Taylor Model Basin. This international symposium was organized jointly by the Office of Naval Research (Mechanics and Energy Conversion S&T Division), the National Research Council (Naval Studies Board), and the Naval Surface Warfare Center, Carderock Division (David Taylor Model Basin). This biennial symposium promotes the technical exchange of naval research developments of common interest to all the countries of the world. The forum encourages both formal and informal discussion of the presented papers, and the occasion provides an opportunity for direct communication between international peers.
Download or read book Development of Experimental Inversion and Simulation Techniques to Study Propeller Blade Response to Inflow Distortion written by and published by . This book was released on 1995 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine propellers usually operate either in the non-uniform wake of a submarine or skewed flow under the stern of a surface ship. Therefore, the flow upstream of marine propeller blades is characterized by irregular patterns which are caused by various mean flow distortions due to the boundary layer growth on the hull of the ship, turbulent viscous wakes of upstream bodies (e.g., Hyun and Patel (1991)) or obstacles (e.g., Groves et al (1992)). Whether the inflow to the propeller is steady or unsteady, uniform or non-uniform, the flow over and downstream of the blades is unsteady. This unsteadiness can be due to a separation bubble near the leading edge of the blade, separated flow from the blade before the trailing edge, as well as tip and hub vortices. The unsteady flow over the blades produces unsteady hydrodynamic forces (i.e., excitations) which result in unwanted vibrations and noise. Inflow nonuniformities give rise to tonal and narrow band noise centered around the blade passing harmonics. Additional broad band signatures are superimposed due to turbulence-trailing edge interaction. Highly non-uniform and asymmetric inflows further exaggerate these effects. (MM).
Download or read book 2023 International Conference on Marine Equipment Technology and Sustainable Development written by Desen Yang and published by Springer Nature. This book was released on 2023-08-01 with total page 1258 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains original, peer-reviewed, and selected research papers that were presented at the 2023 International Conference on Marine Equipment & Technology and Sustainable Development, which took place in Beijing, China on April 1st 2023. The papers cover a range of topics, including but not limited to: the vision and goals of building a maritime community with a shared future, marine machinery and transportation, marine ecology, environmental protection and conservation, marine safety, future ships and marine equipment, marine engineering, marine information and technology, maritime policy, and global governance. The papers included in this volume provide the latest findings on methodologies, algorithms, and applications in marine equipment and technology, as well as sustainable development. As a result, this book is an invaluable resource for researchers, engineers, and university students who are interested in these fields.
Download or read book COMPUTATIONAL STUDIES OF FULLY SUBMERGED BODIES PROPULSORS AND BODY PROPULSOR INTERACTIONS written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Difficulties exist with designing and testing on a model scale. The purpose of this study is to examine variations in the flow field of a submarine due to hull/propulsor interaction and Reynolds scaling. The scope of this study includes the simulation of the flow past a 1) five-bladed marine propeller with 0° skew, 2) unappended submarine hull, 3) forward propelled submarine with asymmetrical stern appendages, and 4) submarine in crashback with asymmetrical stern appendages. The bare hull simulations are conducted for three different length scales: small model scale, large model scale, and full scale. The isolated propeller and appended submarine simulations are conducted on the large model scale. It is of interest how sensitive the various flow characteristics are to Reynolds number and the turbulence model. All simulations are at 0° angle of attack, and validated with experimental data where available.
Download or read book Twenty First Symposium on Naval Hydrodynamics written by National Research Council and published by National Academies Press. This book was released on 1997-09-11 with total page 1100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Submarine Hydrodynamics written by Martin Renilson and published by Springer. This book was released on 2015-03-10 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book adopts a practical approach and presents recent research together with applications in real submarine design and operation. Topics covered include hydrostatics, manoeuvring, resistance and propulsion of submarines. The author briefly reviews basic concepts in ship hydrodynamics and goes on to show how they are applied to submarines, including a look at the use of physical model experiments. The issues associated with manoeuvring in both the horizontal and vertical planes are explained, and readers will discover suggested criteria for stability, along with rudder and hydroplane effectiveness. The book includes a section on appendage design which includes information on sail design, different arrangements of bow planes and alternative stern configurations. Other themes explored in this book include hydro-acoustic performance, the components of resistance and the effect of hull shape. Readers will value the author’s applied experience as well as the empirical expressions that are presented for use at the preliminary design stage. A wide range of state-of-the-art material is included, and there are over fifty references to recent publications in the field. Intended for advanced students and professionals working in the specialised field of submarine hydrodynamics, this book brings theoretical and practical knowledge together in one comprehensive work that is particularly valuable to the submarine hydrodynamicist.
Download or read book Introduction to the Theory of Similarity written by A. A. Gukhman and published by Academic Press. This book was released on 1965 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Large Eddy Simulation for Incompressible Flows written by P. Sagaut and published by Springer Science & Business Media. This book was released on 2013-04-18 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: First concise textbook on Large-Eddy Simulation, a very important method in scientific computing and engineering From the foreword to the third edition written by Charles Meneveau: "... this meticulously assembled and significantly enlarged description of the many aspects of LES will be a most welcome addition to the bookshelves of scientists and engineers in fluid mechanics, LES practitioners, and students of turbulence in general."
Download or read book 2007 Symposium on Underwater Technology and Workshop on Scientific Use of Submarine Cables and Related Technologies written by and published by IEEE Computer Society Press. This book was released on 2007-01-01 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Propulsion written by Justin Elliot Kerwin and published by Society of Naval Architects & Marine Engineers. This book was released on 2010 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive and up-to-date treatment of propeller analysis and design, including beginning with an introduction to various types of marine propulsion machinery, definitions of powers and efficiencies, and two- and three-dimensional airfoil theory. A section on three-dimensional hydrofoil theory introduces wake vortex sheets and three-dimensional vortex lines. These discussions topics are followed by linear lifting line- and lifting surface theory with both exact and approximate solution methods-including properties of helicoidal vortex sheets, optimum and arbitrary circulation distributions, and the Lerbs induction factor method. There are sections on model testing of propellers, propeller strength and followed by selection and design using both standard series charts and by circulation theory. The final section discusses ship standardization trials, their purpose, measurement methods and instruments, concluding with the analysis of trial data and derivation of the model-ship correlation allowance.
Download or read book Karl Fischer Titration written by Eugen Scholz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Karl Fischer titration is used in many different ways following its publication in 1935 and further applications are continually being explored. At the present time we are experiencing another phase of expansion, as shown by the development of new titration equipment and new reagents. KF equipment increasingly incorporates microprocessors which enable the course of a titration to be programmed thus sim plifying the titration. Coulometric titrators allow water determinations in the micro gram-range: the KF titration has become a micro-method. The new pyridine-free re agents make its application significantly more pleasant and open up further possibili ties on account of their accuracy. To make the approach to Karl Fischer titrations easier, we have summarized the present knowledge in this monograph and we have complemented it with our own studies and practical experience. As this book should remain "readable", we have tried to keep the fundamentals to a minimum. Historical developments are only mentioned if they seem to be necessary for understanding the KF reaction. The ap plications are described more fully. Specific details which may interest a particular reader can be found in the original publications cited. The referenced literature is in chronological order as the year of publication may also prove informative. Thus, [6902] for example denotes 69 for 1969 being the year of publication and 02 is a non-recurring progressive number. The referenced litera ture includes summaries which we hope will be of help to find the "right" publica tion easily.
Download or read book A Gallery of Fluid Motion written by M. Samimy and published by Cambridge University Press. This book was released on 2004-01-12 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The visualization of fluid flow has played a major role in the development of fluid dynamics and its applications, from the evolution of flight to tracking weather, and understanding the flow of blood. The Fluid Dynamics Division of the American Physical Society sponsors an annual competition for outstanding images of fluid flow. This volume includes a selection of winners from 1985 to the present. Each image is accompanied by some explanatory text, making the volume an important acquisition for anyone involved in fluid flow research.
Download or read book Practical Ship Hydrodynamics written by Volker Bertram and published by Elsevier. This book was released on 2012 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Practical Ship Hydrodynamics provides a comprehensive overview of hydrodynamic experimental and numerical methods for ship resistance and propulsion, maneuvering, seakeeping and vibration. Beginning with an overview of problems and approaches, including the basics of modeling and full scale testing, expert author Volker Bertram introduces the marine applications of computational fluid dynamics and boundary element methods. Expanded and updated, this new edition includes: Otherwise disparate information on the factors affecting ship hydrodynamics, combined to provide one practical, go-to resource. Full coverage of new developments in computational methods and model testing techniques relating to marine design and development. New chapters on hydrodynamic aspects of ship vibrations and hydrodynamic options for fuel efficiency, and increased coverage of simple design estimates of hydrodynamic quantities such as resistance and wake fraction. With a strong focus on essential background for real-life modeling, this book is an ideal reference for practicing naval architects and graduate students.
Download or read book A Perspective of Constraint Based Reasoning written by Hans W. Guesgen and published by . This book was released on 2014-01-15 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
