Download or read book A Propeller Skew Optimization Method written by and published by . This book was released on 1987 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A propeller operating in the turbulent wake of an axisymmetric body with appendages encounters wake non-uniformities which result in spatial and temporal fluctuations of blade angle-of-attack. These angle-of-attack fluctuations result in unsteady blade loadings and the generation of propeller noise, and the noise sources are characterized by three types of unsteady force mechanisms: a) turbulence injestion; b) vortex shedding; and c) blade-rate. The first two mechanisms typically generate continuous spectrum (broadband) radiated noise levels while blade-rate forces generate discrete frequency noise levels at various blade-passage frequencies and harmonics. This paper will address the reduction of blade-rate noise. The hull boundary layer behind an appendage is characterized by a complex velocity field typically having velocity excesses at inner radii and velocity defects at the outer radii. This type of velocity field has a complex harmonic content distribution and its effect on blade-rate noise cannot be predicted without detailed examination of the wake and the radial distribution of propeller blade forces. The reduction of blade-rate noise and thus vehicle vibration provides the motivation for the application of skew in propeller design. Keywords: Turbulence injestion, Vortex shedding, Blade passage frequencies and harmonics, Blade rate.
Download or read book An Optimization Method for the Reduction of Propeller Unsteady Forces written by Thomas S. Mauther and published by . This book was released on 1988 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the work of Greenblatt (1978), an enhanced optimization technique for the reduction of propeller unsteady forces and the determination of skew distributions has been developed. The current method provides an efficient propeller design tool capable of determining a variety of cubic or quadratic skew distributions, subject to constraints, which minimize the unsteady forces produced by the various harmonic components of the input wake. The original skew optimization method was extended to include higher order harmonics, and the original force calculation method was replaced by an extended version of the method developed by Thompson (1976). Calculation of forces and skew distributions associated with a representative propeller show that acceptable reduction of unsteady forces can be obtained without having to place severe restrictions on the model constraints. The problem considered herein is the generation of propeller noise due to non-uniform inflow velocity fields. This has been still is an issue of research in the area of marine propellers, and it is felt that a recently developed method of calculating unsteady forces may also be applicable in the design and analysis of aircraft propellers. Angle-of-attack fluctuations result in unsteady blade loadings and the generation of propeller noise, and the noise sources are characterized by three types of unsteady force mechanisms: a) turbulence injection; b) vortex shedding; and c) blade-rate.
Download or read book Technical Report Abstracts written by ManTech International Corporation. CADCOM. and published by . This book was released on 1980 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine Propellers and Propulsion written by John Carlton and published by Butterworth-Heinemann. This book was released on 2012-10-30 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early development of the screw propeller. Propeller geometry. The propeller environment. The ship wake field, propeller performance characteristics.
Download or read book Selected Papers from the Sixth International Symposium on Marine Propulsors written by Sverre Steen and published by MDPI. This book was released on 2020-12-29 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine propulsors are key components of the many thousands of ships and boats operating in oceans, lakes, and rivers around the world. The performance of propulsors are important for the environmental impact of ships, underwater noise impact on aquatic fauna, and crew and passenger comfort and safety. This book presents nineteen papers devoted to the hydrodynamics of different types of marine propulsors (conventional propellers, thrusters, and novel solutions). Most of the papers are extended papers from the sixth International Symposium on Marine Propulsors (SMP 2019). Several of the papers deal with cavitation, vortices, and energy saving devices. The papers present high-quality research performed using Computational Fluid Dynamics (CFD) and Experimental Fluid Dynamics (EFD) as well Artificial Intelligence (AI).
Download or read book The Shock and Vibration Digest written by and published by . This book was released on 1988 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1988-06 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Basic Ship Propulsion written by J. P. Ghose and published by Allied Publishers. This book was released on 2004 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Practical Methods for Predicting Periodic Propeller Loads written by Robert J. Boswell and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MRIS Abstracts written by Maritime Research Information Service and published by . This book was released on 1979 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MARAD the Annual Report of the Maritime Administration written by United States. Maritime Administration and published by . This book was released on 1974 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA 26th Aerospace Sciences Meeting written by and published by . This book was released on 1988 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Marine Propellers and Propulsion written by John Carlton and published by Butterworth-Heinemann. This book was released on 2018-11-30 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine Propellers and Propulsion, Fourth Edition, offers comprehensive, cutting edge coverage to equip marine engineers, naval architects or anyone involved in propulsion and hydrodynamics with essential job knowledge. Propulsion technology is a complex, multidisciplinary topic with design, construction, operational and research implications. Drawing on experience from a long and varied career in consulting, research, design and technical investigation, John Carlton examines hydrodynamic theory, materials and mechanical considerations, and design, operation and performance. Connecting essential theory to practical problems in design, analysis and operational efficiency, the book is an invaluable resource, packed with hard-won insights, detailed specifications and data. - Features comprehensive coverage of marine propellers, fully updated and revised, with new chapters on propulsion in ice and high speed propellers - Includes enhanced content on full-scale trials, propeller materials, propeller blade vibration, operational problems and much more - Synthesizes otherwise disparate material on the theory and practice of propulsion technology from the past 40 years' development, including the latest developments in improving efficiency - Written by a leading expert on propeller technology, essential for students, marine engineers and naval architects involved in propulsion and hydrodynamics
Download or read book MARAD written by United States. Maritime Administration and published by . This book was released on 1978 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Government Reports Announcements Index written by and published by . This book was released on 1988 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Fluids Engineering written by and published by . This book was released on 1998 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
