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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: Publisher: ISBN: Category : Languages : en Pages : 158
Book Description
As part of a 2014 thesis, the MIT Innovative Ship Laboratory (iShip) designed a high-speed planing hull form that was based on the Model Variant 5631 developed at the US Navy's David Taylor Model Basin [7] [3] [5]. This model was a variant of the parent hull 5628. The 5631 variant was a model of the 47 foot Motor Lifeboat of the US Coast Guard, which was a hard chine, deep-vee vessel. Model 5631 had no step, with a 20 degree dead rise angle. The Clement method [4] was used in order to design a cambered planing surface that would generate dynamic lift and support most of the weight of the vessel. A second cambered step was designed using an in-house lifting surface program. The step was designed such that, at top speed, the entire hull aft of the step would be ventilated. To accommodate this effect, the aft underbody design departed from the conventional dead-rise. Directional stability of the model in the pre-planing regime was increased by incorporating three vertices at the design dead-rise angle. A set of super-cavitating, surface-piercing hydrofoils were designed to be attached aft of the vessel transom in order to provide support and prevent re-wetting of the afterbody. The constructed hydrofoils were positioned in a vee configuration, differing from the anhedral design in the Faison thesis. A support manual control system for the hydrofoils was designed as part of this thesis. Known as Model 5631D, this dynaplane model underwent a series of tests at the 380 foot towing tank at the United States Naval Academy in Annapolis, Maryland, over the course of several days. Several parameters were varied during the tests: the cambered step (via the wedge insert), the carriage speed, and the model longitudinal center of gravity (LCG). In this thesis, data from the series of tests of Model 5631D will be compared to that of the tests of Model 5631 by combining methods from Savitsky [15] and Faltinsen [8] for data scaling of planing vessels. Both models were scaled to the same static waterline length in order to determine the efficacy of the new design changes of Model 5631D in reducing total drag. Additionally, comparisons of the test data were made to computational fluid dynamics models conducted under the same conditions in the virtual environment. An introduction and motivation for the thesis is presented in Chapter 1. Half and full factorial statistical analysis was performed on the testing data and presented in Chapter 2, along with the results of data scaling and comparison of Hull 5631D's performance to the parent hull. Results of the CFD simulations along with calculation of model stability is presented in Chapter 3. Conclusions and opportunities for future work are given in Chapter 4. A full catalogue of the testing data is given in Appendix A.
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: 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: Peter R. Payne Publisher: ISBN: Category : Languages : en Pages : 22
Book Description
The intolerable pounding of conventional planing hulls is the chief reason for the development of alternative hydrofoil and SES vehicles, in an attempt to achieve high speeds with motions that are commercially and militarily acceptable. This approach has been to find out why a conventional planing hull pounds, and then to devise new planing hull forms which avoid the problem. Work over the last ten years, including a dozen experimental boats, has resulted in forms which largely meet this objective. Experimental data indicates that the latest hull - the SEA KNIFE - has a better ride than SES or surface-piercing hydrofoils, and for a much lower cost, is not much inferior to the fully-submerged hydrofoil.
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: Leon Alexander Faison
Author: Leon Alexander Faison
Author: 
Author: Calley Dawn Gray
Author: Zvi Sheingart
Author: Virgil E. Johnson
Author: Joseph Norwood
Author: Peter R. Payne
Author: Miles Patrick Wheeler
Author: Gibbs & Cox
Author: Zu-Shun Dong