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Author: Leon Alexander Faison Publisher: ISBN: Category : Languages : en Pages : 82
Book Description
Design of a high speed planing hull is analyzed by implementing a cambered step and stem, surface piercing hydrofoils, commonly known as a Dynaplane hull. This configuration combines the drag reduction benefits of a stepped hull with a fully ventilated after body by using a stem stabilizer. The largest obstacle with this design is maintaining trim control and stability at high speeds. There has been limited research on the Dynaplane design since Eugene Clement first conducted tow tank tests in the David Taylor Model Basin (DTMB) in the 1960s. Modem experimental methods such as computational fluid dynamics (CFD) allow the designer to run multiple simulations at once while testing a variety of parametric variables. The analysis will combine theoretical, empirical, and computational methods to determine the hydrodynamic characteristics of the design and develop a new Dynaplane configuration that allows for speeds in excess of 50 knots. The design approach begins with using a reference hull named Model 5631 from a small systematic series of resistance tests at the DTMB. This modeled hull is based on the U.S. Coast Guard 47 ft Motor Lifeboat which is a hard chine, deep V planing hull. Clement's Dynaplane design process was followed with exception of the stem stabilizer recommendation. Instead, a surface piercing super cavitating (SPSC) hydrofoil designed by Dr. Stefano Brizzolara was used. These designs further improve upon the powering requirements of a conventional planing hull by effectively increasing the lift to drag ratio. A commercially available CFD software program called Star-CCM+ is used for the computational portion. The computational model is first validated using results from the Model 5631 tow tank tests. Three series of CFD tests were then conducted on the new Dynaplane design; which include developing wake geometry predictions for a swept back stepped hull, and then varying the trim angle and longitudinal center of gravity. These tests were run at an FnV=5 in a calm sea state. Results from the analysis demonstrate the benefits of a fully ventilated afterbody using the SPSC hydrofoils and predict the hydrodynamic behavior for the new design. Also, the results extend the range of application of Clement's Dynaplane design to hulls with 20 degree deadrise. This thesis gives naval architects design guidance for such a hullform and demonstrates the potential of CFD as a tool for analyzing these parametric variables.
Author: Leon Alexander Faison Publisher: ISBN: Category : Languages : en Pages : 82
Book Description
Design of a high speed planing hull is analyzed by implementing a cambered step and stem, surface piercing hydrofoils, commonly known as a Dynaplane hull. This configuration combines the drag reduction benefits of a stepped hull with a fully ventilated after body by using a stem stabilizer. The largest obstacle with this design is maintaining trim control and stability at high speeds. There has been limited research on the Dynaplane design since Eugene Clement first conducted tow tank tests in the David Taylor Model Basin (DTMB) in the 1960s. Modem experimental methods such as computational fluid dynamics (CFD) allow the designer to run multiple simulations at once while testing a variety of parametric variables. The analysis will combine theoretical, empirical, and computational methods to determine the hydrodynamic characteristics of the design and develop a new Dynaplane configuration that allows for speeds in excess of 50 knots. The design approach begins with using a reference hull named Model 5631 from a small systematic series of resistance tests at the DTMB. This modeled hull is based on the U.S. Coast Guard 47 ft Motor Lifeboat which is a hard chine, deep V planing hull. Clement's Dynaplane design process was followed with exception of the stem stabilizer recommendation. Instead, a surface piercing super cavitating (SPSC) hydrofoil designed by Dr. Stefano Brizzolara was used. These designs further improve upon the powering requirements of a conventional planing hull by effectively increasing the lift to drag ratio. A commercially available CFD software program called Star-CCM+ is used for the computational portion. The computational model is first validated using results from the Model 5631 tow tank tests. Three series of CFD tests were then conducted on the new Dynaplane design; which include developing wake geometry predictions for a swept back stepped hull, and then varying the trim angle and longitudinal center of gravity. These tests were run at an FnV=5 in a calm sea state. Results from the analysis demonstrate the benefits of a fully ventilated afterbody using the SPSC hydrofoils and predict the hydrodynamic behavior for the new design. Also, the results extend the range of application of Clement's Dynaplane design to hulls with 20 degree deadrise. This thesis gives naval architects design guidance for such a hullform and demonstrates the potential of CFD as a tool for analyzing these parametric variables.
Author: Calley Dawn Gray Publisher: ISBN: Category : Languages : en Pages : 74
Book Description
With emerging applications for high speed boats in commercial, military and off shore industries, there is a focus in the naval architecture community to improve the efficiency and performance characteristics of planing hulls. In the 1960's, Eugene Clement showed that considerable reductions in resistance at high speeds can be obtained by converting a conventional planing hull to a Dynaplane stepped planing hull. A Dynaplane stepped planing hull refers to a hull configuration where the majority of lift is provided by a swept back cambered surface, while the remainder of the lift is provided by an aft lifting surface that also provides trim control and stability. The afterbody is fully ventilated by use of a V-shaped step positioned at the trailing edge of the cambered surface. Clement's semi-empirical conversion method was based off tests performed at the David Taylor Model Basin and is limited to boats with a deadrise of less than 15°. Since the publication of his paper, advancements in CFD programs have made it possible to conduct accurate simulations of planing hulls with complex geometry, allowing for further development of Clement's method. This thesis expands Clement's method to high deadrise by applying it to a notional version of the Mark V Special Operations Craft used by the United States Navy with a design speed of 55kts. CFD simulations with fixed trim were run in order to refine the cambered surface, design the step and afterbody, to position the hydrofoil and to test the low speed performance of the interceptor. Once the hull design was finalized, simulations with two degrees of freedom were run to assess the dynamic stability of the hull. Through simulations, it was found that the configuration is dynamically stable and is able to reduce hull resistance at design speed by as much as 54% when compared with that of the original hull.
Author: Miles Patrick Wheeler Publisher: ISBN: Category : Hydrofoils Languages : en Pages : 139
Book Description
This dissertation is focused on heavily loaded planing hulls and high-lift hydrofoils operating in moderate Froude-number regimes, which are important for a variety of military and civil marine applications. The research described here entails high-fidelity computational fluid dynamics simulations of flows around prismatic planing hulls and surface-piercing hydrofoils. The physical models involved in numerical simulations include viscous, multi-phase, turbulent, and unsteady phenomena. Verification and validation studies for all considered problems have been conducted, followed by parametric studies of selected hull and hydrofoil configurations.The planing-hull investigation analyzed constant-deadrise hulls with various bow shapes. Both normal and heavily loaded conditions were considered in broad speed regimes from the displacement to planing mode and two characteristic locations of the center of gravity. The hull with a concave bow was found to perform best, as it had lower drag at transitional speeds in the overloaded state and lower drag at fastest speeds at normal loading.The high-lift flexible hydrofoils having isotropic and orthotropic material properties, which imitate composite structures, were numerically modeled in calm water and in head waves. To investigate fluid-structure interactions associated with flexible hydrofoils, numerical solutions were obtained using coupled fluid and solid solvers, as well as morphing and overset meshing methodology. Effects of materials properties on hydrodynamic characteristics and structural deformations of hydrofoils were determined. Specifically, orthotropic hydrofoils with fibers directed from the fixed root to the leading edge exhibited negative twist, lower lift coefficients in calm water and lower lift oscillations in waves. Hydrofoils with fibers oriented towards the railing edge manifested higher twist and lift forces in calm water, and larger oscillations in wave conditions.Additional studies of high-lift surface-piercing hydrofoils subjected to ventilation by atmospheric air were conducted. The air ventilation usually results in substantial decrease of the lift force. To counteract this process, an application of small fences on the foil surface was numerically investigated. It was found that these elements can suppress air ventilation, thus increasing lifting capabilities and improving lift-drag ratio of hydrofoils at moderate Froude numbers.
Author: Zu-Shun Dong Publisher: Springer ISBN: 9783031627590 Category : Transportation Languages : en Pages : 0
Book Description
High Speed Monohull and Hydrofoil Craft: Performance, Technology, and Applications provides comprehensive coverage of the basic hydrodynamics of high-speed monohulls and hydrofoil craft useful to students and engineers alike. The first half of the book introduces different hull shapes for semi-planing and planing craft with examples from their development through the last century. Succeeding chapters then describe the hydrodynamic theory behind their performance in calm water and a seaway. They also document the extensive series of model test programs naval architects use to create prediction models for resistance and powering. Electronic versions of a number of these are included for readers’ use. A final chapter on monohulls looks at hull geometric form that has been developed to provide the best possible combination of resistance in waves and motion response through a combination of a deep and sharp forefoot and a hard chine cross-section towards the stern for patrol vessels and offshore logistics craft. The book’s second half introduces the various geometries and planform configurations of hydrofoils under a fast craft hull. It reviews the development of these craft for inland waterways, such as major river systems, and the rougher environment of seaways, such as the Mediterranean and Atlantic oceans. It is followed by hydrofoil theory in an ideal fluid close to a free surface. Then the theory for a real fluid includes the vorticity and effect of planform, dihedral, and surface interaction. Hydrofoil craft design and analysis are covered next. Finally, there is a chapter on special configurations, such as craft having foils just at the bow and hydrofoil craft based on catamaran hulls.
Author: Zvi Sheingart Publisher: ISBN: Category : Languages : en Pages : 94
Book Description
The influence of a cambered shaped bottom step on the performance of sea going V-stepped planing hulls is investigated using numerical methods. The shape of the step was designed to decrease the Drag/Lift ratio of the hull in full planing regime (Fr[delta sign turned upside down] = 6 ). A numerical method, complementary to the existing empirical method developed by Clement for design of a cambered step has been developed. The numerical approach described in this thesis extends the empirical Clement's method for stepped hull design to hard chine hulls with higher deadrise. The stem trim stabilizer has been replaced by supercavitating hydrofoils. Several foil/step configurations were numerically tested. RANSE code is used to evaluate the performance of new hull design with a stepped bottom. Prototypes of the hull have been modeled in 3D using Rhino, NURBS surface modeler. Two validation cases have been considered to validate the RANSE models used for the numerical prediction of hydrodynamic characteristics: Geritsma's 25° deadrise hull series and original Clement's 12.5° deadrise hull (DTMB Model 5115). Numerical results showed good agreement with experimental data, except for the pre-planing regime, where an influence of the towing rig on the CG rise was not negligible. The baseline for the design of the hybrid stepped hull chosen to be Geritsma's 25° hull with length to maximum beam ratio of 4.09. The thesis confirms the applicability of Clement's method on deep-V seagoing hulls. Total reduction of 3% in Drag/Lift ratio has been achieved, but can be further reduced. All the RANSE calculations were performed using Star-CCM+® software package on the 400 cores HPC cluster of MIT i-Ship lab.
Author: Dejan Radojčić Publisher: Springer ISBN: 3319948997 Category : Technology & Engineering Languages : en Pages : 111
Book Description
This SpringerBrief focuses on modeling and power evaluation of high-speed craft. The various power prediction methods, a principal design objective for high-speed craft of displacement, semi-displacement, and planing type, are addressed. At the core of the power prediction methods are mathematical models for resistance and propulsion efficiency. The models are based on the experimental data of various high-speed hull and propeller series. The regression analysis and artificial neural network (ANN) methods are used as an extraction tool for this kind of mathematical models. A variety of mathematical models of this type are discussed in the book. Once these mathematical models have been developed and validated, they can be readily programmed into software tools, thereby enabling the parametric analyses required for the optimization of a high-speed craft design. This book provides the foundational reference for these software tools, and their use in the design of high-speed craft. High-speed craft are very different from conventional ships. Current professional literature leaves a gap in the documentation of best design practices for high-speed craft. This book is aimed at naval architects who design and develop various types of high-speed vessels.
Author: Lawrence Benen Publisher: ISBN: Category : Languages : en Pages : 21
Book Description
A model of a catamaran planing boat was equipped with a diamond-shaped surface-piercing hydrofoil to eliminate instabilities encountered with an earlier foil configuration (TMB Report 1852). The hydrofoil configuration was located forward of the center of gravity, and two high deadrise planing surfaces integral with the hull were located aft of the center of gravity. Smooth water resistance tests were made with various LCG locations; and with the foils at various angles of attack and various fore and aft positions, to determine an optimum configuration. Model speed, resistance, trim, and wetted length were measured throughout the speed range for a number of foil positions, foil angles, and hull trims. The best condition from a stability and resistance standpoint was then expanded to full scale. The results for the optimum configuration are presented in dimensionless form and also in the form of trim and ehp versus full-scale speed in knots. R/delta comparisons are also made for the foil-maran, the parent catamaran hull, and a conventional planing hull. At high speed the resistance of the foil-maran was less than that of the catamaran. However, the resistance of the foil-maran was considerably greater than that of the conventional planing hull at all speeds. (Author).
Author: Lawrence Benen Publisher: ISBN: Category : Languages : en Pages : 45
Book Description
General resistance tests of TMB Model 4776, a transverse stepped planing hull, were conducted. The hull is the third model tested to determine suitability for use as a hydrofoil hull. Resistance, trimming moment, and wetted lengths were measured for several load, trim, and speed conditions. All data are presented in nondimensional form for use in comparing hull forms. The tests indicated that the model at high speed coefficients has low moment and resistance characteristics which would be advantageous to a hydrofoil configuration. Although instabilities due to spray and inadequate step ventilation were found, the trim conditions at which these instabilities occur can be avoided during the normal takeoff operation. (Author).
Author: Leon Alexander Faison
Author: Leon Alexander Faison
Author: Calley Dawn Gray
Author: Miles Patrick Wheeler
Author: Zu-Shun Dong
Author: Zvi Sheingart
Author: Dejan Radojčić
Author: Virgil E. Johnson
Author: 
Author: Lawrence Benen
Author: Lawrence Benen