Download or read book Numerical Modeling of a Hydrofoil Or a Marine Propeller Undergoing Unsteady Motion Via a Panel Method and RANS written by Abhinav Sharma (master of science in civil engineering.) and published by . This book was released on 2011 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational approach to analyze the hydrodynamic performance of a hydrofoil or a marine propeller undergoing unsteady motion has been developed. In order to simulate heave and pitch motion of a hydrofoil, an unsteady boundary element method based modeling is performed. The wake of the hydrofoil is modeled by a continuous dipole sheet and determined in time by applying a force-free condition on its surface. An explicit vortex core model is adapted in this model to capture the rolling up shape and to avoid instability due to roll-up deformation of the wake. The numerical results of the developed model are compared with analytical results and those from the commercial Reynolds-Averaged Navier-Stokes solver (ANSYS/FLUENT). The results show close level of agreement with each other. The problem of flow around a marine propeller performing surge, roll and heave motion in an unbounded fluid is formulated and solved using both a vortex-lattice method and a boundary element method. A fully unsteady wake alignment algorithm is implemented into the vortex-lattice method in order to satisfy the force-free condition on the propeller wake surface. Finally, a comparative study of transient propeller forces on a propeller blade obtained from BEM and VLM (with or without fully aligned wake) is carried out and results are presented. In some cases, results from the presented methods are compared with those from RANS or other numerical methods available in the literature.
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 Unsteady Aerodynamics and Aeroelasticity of Turbomachines written by Yoshimichi Tanida and published by Elsevier Publishing Company. This book was released on 1995 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contributed papers in this volume cover a variety of unsteady flow phenomena in turbomachines. They present theoretical and numerical modellings plus experimental techniques and findings on the unsteady flows in turbomachines.
Download or read book A Panel Method for the Prediction of Unsteady Hydrodynamic Performance of the Ducted Propeller with a Finite Number of Blades written by Jinzhang Feng and published by . This book was released on 1985 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Propeller Forces Fundamental Hydrodynamics and Unconventional Propulsion written by Ralph D. Cooper and published by . This book was released on 1971 with total page 1700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modelling and Simulation of Cavitating Marine Propeller Flows written by Maria Gaschler and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-dimensional inviscid boundary element method for the simulation of steady and unsteady partial sheet cavitation on marine propellers is developed. The numerical method is validated in several test cases and applied to the calculation of hydrodynamic loads generated by the flow field around and behind a cavitating propeller on the surrounding structures in the port area.
Download or read book Hamburg Model Basin written by Joachim K. Krohn and published by . This book was released on 1961 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Further Measurements of Model Propeller Pressure Distributions Using a Novel Technique written by Stuart D. Jessup and published by . This book was released on 1986 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model propeller blade pressure distributions were measured using a novel technique. A single pressure gage was installed at a radial position to measure pressures at numerous chordwise locations through pressure taps and connecting channels. The technique resulted in accurate, detailed pressure distributions along two radial positions using two pressure gages. The major advantage of this technique is the ability to make measurements in the thin parts of the blade with high potential accuracy, and no disruption to the measuring surface, except for the orifice hole. The relatively along test time required to collect the data is the disadvantage. Keywords: Marine Propeller, Propeller Research Pressure Distribution, Model Experiments.
Download or read book Numerical Methods for Propeller Aerodynamics and Acoustics at DFVLR written by N. Kroll and published by . This book was released on 1987 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the DFVLR Institute for Design Aerodynamics, linear and nonlinear analysis methods for flow fields around propellers have been developed. Two singularity methods are presented. In the first, a doublet point scheme has been formulated for the calculation of steady and unsteady loads on surfaces having helical motion in an incompressible medium, e.g. propellers in uniform and nonuniform inflows and counter rotating propellers. The second is a surface panel method for computations of steady subsonic flows around propeller blades moving in a compressible medium. The method has been extended for the prediction of acoustic quantities. In order to predict the characteristics of transonic propeller flow fields, the DFVLR Euler code for solving the 3-D Euler equations has been extended. The equations are formulated in a rotating cartesian reference frame. The solution procedure is based on a finite volume method using an explicit Runge-Kutta time stepping scheme. Numerical results for various propeller geometries are presented and compared with experimental data.
Download or read book RANS Computation of Propeller Tip Vortex Flow for Steady and Unsteady Cases written by Md. Shafiul Azam Mintu and published by . This book was released on 2011 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrodynamics of Ship Propellers written by John P. Breslin and published by Cambridge University Press. This book was released on 1994 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technical introduction to ship propeller hydrodynamics, for researchers in ocean technology, naval architecture, mechanical engineering.
Download or read book Marine Propeller Analysis with Panel Method written by C-I. Yang and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Prediction of Unsteady Sheet Cavitation on Marine Propellers written by Defence Research Establishment Atlantic and published by [Dartmouth, N.S.] : Defence Research Establishment Atlantic. This book was released on 1987 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document describes the theory and numerical methods used in the propeller analysis program CAVITY for the prediction of periodic back sheet cavitation on marine propellers operating in a ship's wake. Sheet cavitation chordwise extents and thickness distributions can be predicted at up to 60 blade angular positions per revolution for a given propeller geometry, operating condition and ship wake inflow in the propeller rotation plane. The procedures used in CAVITY are based on lifting surface methods as an extension of the PUF-2 code for predicting both steady and unsteady propulsive performance characteristics of marine propellers. The original procedures for the prediction of back sheet cavitation are reviewed and some modifications concerning chordwise distributions of singularities and propeller wake modelling are described. These changes are incorporated to improve predictions of leading edge cavitation development as well as results obtained at off-design operating conditions. Numerical extents obtained with CAVITY are compared to available experimental data. Provided that representative ship wake data are used, the predictions to data for back sheet cavitation show good agreement with experimentally observed extents developing on thin blade sections.
Download or read book Numerical Prediction of Underwater Noise Induced by Non cavitating cavitating Propellers written by Seungnam Kim and published by . This book was released on 2021 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, a systematic procedure of analyzing marine propeller performance and its underwater acoustics is delineated. The main focus is laid on the numerical prediction of hull pressure fluctuations and far-field acoustics induced by marine propellers via frequency- or time-domain approaches. As the first step, a hydrodynamic boundary element method (BEM) is implemented to analyze the comprehensive marine propeller performance in open water and ship-behind conditions. An elaborate numerical scheme modeling developed tip vortex cavitation is proposed for cavitating propellers. In the frequency domain approach, a potential-based panel method (or pressure-BEM) solving for the diffraction potential on the ship hull is coupled with the hydrodynamic BEM to predict the propeller-induced hull pressure fluctuations. Infinite speed of sound is assumed in the near-field, neglecting the time travel of acoustic waves to reduce the Helmholtz equation to the Laplace equation, which can be solved by a standard BEM solver. Far-field underwater noise is investigated in the time domain using the Ffowcs Williams-Hawkings (FW-H) formulation. The model propeller is mounted on the ship with an infinite plane assumed at the design draft to consider the pressure release or solid wall boundary conditions. Time-dependent surface quantities from the hydrodynamic analysis are taken as the known noise sources to the FW-H equation given in the form proposed by Farassat. The complex hull geometry and its disturbance to the medium are considered by solving the boundary integral equations. A half-space domain is modeled by modifying standard full-space Green's function to consider the image model beyond the infinite plane. The propeller-induced noise, its reflections from the hull, and their sums as the total noise will be investigated in full-space or half-space domains. Numerical predictions, including the time history of acoustic pressures and noise spectra, under various operating conditions are compared with experimental measurements, observations, and results from finite volume methods to validate the feasibility and accuracy of the present method
Download or read book Development and Analysis of Panel Methods for Propellers in Unsteady Flow written by Ching-Yeh Hsin and published by . This book was released on 1990 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Potential Based Panel Method for the Analysis of Marine Propellers in Steady Flow written by Jin-Tae Lee and published by . This book was released on 1987 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: A surface panel method suitable for the analysis of marine propellers is developed and applied to various geometries to demonstrate its effectiveness. A reliable pressure distribution around a marine propeller, especially near the leading edge of the blade, is obtained. Hub effects are naturally included by distributing panels on the hub surface. Detailed study of the flows at the trailing edge near the tip suggests a pressure Kutta condition, which requires the pressures of the last panels at the trailing edge be equal. Due to the nonlinear aspect of the pressure Kutta condition, an iterative process is employed. An efficient approximation of the ultimate wake is achieved by replacing it with a sink disk a the beginning of the ultimate wake. The sample geometries include an ellipsoid at zero angle of attack, a circular planform wing, a rectangular planform wing with varying sweep angles, a wing-body configuration, a long axisymmetric duct, and a marine propeller. Calculated pressure distributions around the wing-body configuration are in excellent agreement with the experimental data. Calculated thrust and torque for the propeller agree well experimental results.
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.
