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 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 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 Partially Cavitating Cascade Theories and Their Application to Cavitating Propeller Flows written by Okitsugu Furuya and published by . This book was released on 1979 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to the previously developed partially cavitating cascade theory, two new flow models were constructed in search of a better flow model for determining accurate force coefficients. Effort has been made for obtaining (1) physically acceptable flows, particularly the location of cavity boundary and (2) smooth matching of the flow characteristics between the partially cavitating and supercavitating flow regimes. Based on the numerical results made with these flow models for practical blade profiles taken after a supercavitating propeller it was found that no single flow model developed above could handle the complete set of cascade geometries and incidence angles. One theory was supplemental to the other and no definite guideline was discovered for selection of an appropriate flow model for a specified flow condition to be solved except for a few weak evidences. The data calculated with one of the above theories were used in the high speed propeller theory for predicting the performance of a supercavitating propeller operating at the partially cavitating regime. The results showed a slight improvement over the previous ones, indicating a good possibility of increasing the prediction capability of the propeller theory for the partial cavitating flow regime. In doing this, a more accurate theory will have to be developed. Before making further effort on developing such a theory, many unknown aspects regarding the boundary condition of the partially cavitating cascade flow should be clarified. A systematic experimental study for such flow is now in order and strongly recommended. (Author).
Download or read book Ship Resistance and Propulsion written by Anthony F. Molland and published by Cambridge University Press. This book was released on 2011-08-08 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by experts in the ship design field, this book provides a comprehensive approach to evaluating ship resistance and propulsion.
Download or read book Performance of Propeller 4381 in Crashback written by Christopher J. Chesnakas and published by . This book was released on 2004-12-01 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propeller operation in crashback is technically very challenging, both computationally and experimentally. Propeller 4381 was evaluated experimentally in Carderock's 36-inch (0.91 m) water tunnel. Propeller 4381 was operated in the ahead condition for comparison. Details of the flow field were measured with 3-component laser Doppler velocimetry (LDV) and 2-component particle imaging velocimetry (PIV). Propulsion performance was measured with thrust and torque transducers. Cavitation was documented photographically with a strobe light, and flow visualization was conducted with a vertical laser light sheet for observation of the recirculation region of the propeller in crashback. Results showed that highly random cavitation occurred on the propeller in crashback on the downstream side at the leading edge, which is the trailing edge for ahead. A highly unstable recirculation zone occurred with a ring vortex near the propeller tip. The maximum variation in thrust and torque as computed from the standard deviation relative to the mean load with a value of 0.25 occurred at an advance ratio of J = -0.5. The high variation in loads appeared to correlate with the maximum total kinetic energy relative to tunnel velocity in the flow at the blade tip, which was measured by LDV as 1.5. These results indicate that vibration and wear may be reduced by minimizing operation near J = - 0.5 for this propeller.
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 One for the Road written by Bjørn Christian Tørrissen and published by One for the Road. This book was released on 2008-01-07 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building on experience from 60 countries worth of independent travel, the author takes you on three journeys to places you may never have considered visiting, although you probably should and you definitely could. Learn about a low-budget cruise to Antarctica, understand what the Trans-Siberian Railway really is like, enjoy the natural wonders of Southern Africa. The book is a fun read, but you will also learn about far-away destinations and about how to travel independently anywhere. It's not a travel guide or a travel journal, it's both!More details, including free downloads, available from http://bjornfree.com/
Download or read book The Kinematics of Vorticity written by Clifford Truesdell and published by Courier Dover Publications. This book was released on 2018-10-17 with total page 259 pages. Available in PDF, EPUB and Kindle. Book excerpt: "When all has been said, one important fact emerges: this book is a valuable compendium of results that every expert in hydrodynamics, gas dynamics, or dynamical meteorology will want to keep by … [their]side and refer to frequently." — Bulletin of the American Mathematical Society This unique graduate-level monograph offers a heavily mathematical treatment of the vorticity of fluids. The subject's wealth of applications extends to many areas of physics and engineering, and the book will also appeal to mathematically oriented historians of science. Starting with consideration of geometrical and kinematical preliminaries, the text advances to examinations of vorticity, the vorticity field, vorticity measures, and vorticity averages. Subsequent chapters explore Bernoullian theorems, convection and diffusion of vorticity, and circulation-preserving motions.
Download or read book Complex Effects in Large Eddy Simulations written by Stavros Kassinos and published by Springer Science & Business Media. This book was released on 2007-07-16 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of Large Eddy Simulations is reaching a level of maturity that brings this approach to the mainstream of engineering computations, while it opens opportunities and challenges. The main objective of this volume is to bring together leading experts in presenting the state-of-the-art and emerging approaches for treating complex effects in LES. A common theme throughout is the role of LES in the context of multiscale modeling and simulation.
Download or read book Advanced Approaches in Turbulence written by Paul Durbin and published by Elsevier. This book was released on 2021-07-24 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Approaches in Turbulence: Theory, Modeling, Simulation and Data Analysis for Turbulent Flows focuses on the updated theory, simulation and data analysis of turbulence dealing mainly with turbulence modeling instead of the physics of turbulence. Beginning with the basics of turbulence, the book discusses closure modeling, direct simulation, large eddy simulation and hybrid simulation. The book also covers the entire spectrum of turbulence models for both single-phase and multi-phase flows, as well as turbulence in compressible flow. Turbulence modeling is very extensive and continuously updated with new achievements and improvements of the models. Modern advances in computer speed offer the potential for elaborate numerical analysis of turbulent fluid flow while advances in instrumentation are creating large amounts of data. This book covers these topics in great detail. Covers the fundamentals of turbulence updated with recent developments Focuses on hybrid methods such as DES and wall-modeled LES Gives an updated treatment of numerical simulation and data analysis
Download or read book Marine Rudders and Control Surfaces written by Anthony F. Molland and published by Elsevier. This book was released on 2011-02-24 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine Rudders and Control Surfaces guides naval architects from the first principles of the physics of control surface operation, to the use of experimental and empirical data and applied computational fluid dynamic modelling of rudders and control surfaces.The empirical and theoretical methods applied to control surface design are described in depth and their use explained through application to particular cases. The design procedures are complemented with a number of worked practical examples of rudder and control surface design. • The only text dedicated to marine control surface design• Provides experimental, theoretical and applied design information valuable for practising engineers, designers and students• Accompanied by an online extensive experimental database together with software for theoreticalpredictions and design development
Download or read book The Wageningen Propeller Series written by G. Kuiper and published by . This book was released on 1992 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Marine Propulsors written by Sverre Steen and published by MDPI. This book was released on 2018-10-10 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Marine Propulsors" that was published in JMSE
Download or read book Wind Energy Handbook written by Tony Burton and published by John Wiley & Sons. This book was released on 2001-12-12 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: As environmental concerns have focused attention on the generation of electricity from clean and renewable sources wind energy has become the world's fastest growing energy source. The Wind Energy Handbook draws on the authors' collective industrial and academic experience to highlight the interdisciplinary nature of wind energy research and provide a comprehensive treatment of wind energy for electricity generation. Features include: An authoritative overview of wind turbine technology and wind farm design and development In-depth examination of the aerodynamics and performance of land-based horizontal axis wind turbines A survey of alternative machine architectures and an introduction to the design of the key components Description of the wind resource in terms of wind speed frequency distribution and the structure of turbulence Coverage of site wind speed prediction techniques Discussions of wind farm siting constraints and the assessment of environmental impact The integration of wind farms into the electrical power system, including power quality and system stability Functions of wind turbine controllers and design and analysis techniques With coverage ranging from practical concerns about component design to the economic importance of sustainable power sources, the Wind Energy Handbook will be an asset to engineers, turbine designers, wind energy consultants and graduate engineering students.
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.
