A study on vertical motions of high-speed planing boats with automatically controlled stern interceptors in calm water and head waves

2014 ◽  
Vol 10 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Mohammad Hossein Karimi ◽  
Mohammad Saeed Seif ◽  
Majid Abbaspoor
Keyword(s):  
High Speed ◽  
Head Waves ◽  
Calm Water

Comparison between the Dynamic Behavior of the Non-stepped and Double-stepped Planing Hulls in Rough Water: A Numerical Study

2020 ◽  
Vol 36 (01) ◽  
pp. 52-66
Author(s):  
Arman Esfandiari ◽  
Sasan Tavakoli ◽  
Abbas Dashtimanesh
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Numerical Study ◽  
Vertical Plane ◽  
Recent Decade ◽  
Vertical Acceleration ◽  
Gravitational Acceleration ◽  
Head Waves ◽  
Calm Water ◽  
Rough Water

Reducing vertical motions of high-speed planing hulls in rough water is one of the most important factors that help a boat to become more operable, and will benefit the structure of the boat and the crew on board. In the recent decade, stepped planing hulls have been investigated with emphasis on their better performance in calm water than that of nonstepped planing hulls. However, there are still doubts about their performance in rough water. In this study, we investigate this problem by providing numerical simulations for motions of a double-stepped and a non-stepped planing hull in a vertical plane when they encounter head waves. The problem will be solved using the finite volume method and volume of fluid method. To this end, a numerical computational fluid dynamics code (STARCCM1) has been used. Accuracy of the numerical simulations is evaluated by comparing their outcome with available experimental data. The dynamic response of the investigated hulls has been numerically modeled for two different wave lengths, one of which is smaller than the boat length and the other which is larger than the boat length. Using the numerical simulations, heave and pitch motions as well as vertical acceleration are found. It has been found that at wave lengths larger than the boat length, heave amplitude decreases by 10–40%when two steps are added to the bottom of a vessel. It has also been observed that pitch of a planing hull is reduced by 18–32% in the presence of the two steps on its bottom. Finally, it has been observed that for wave lengths larger than the boat length, the maximum vertical acceleration decreases by a gravitational acceleration of about .2–.7.

Comparative Performance of Optimum High Speed SWATH and Semi-SWATH in Calm Water and in Waves

2015 ◽  
Author(s):  
S. Brizzolara ◽  
G. Vernengo ◽  
L. Bonfiglio ◽  
D. Bruzzone
Keyword(s):  
High Speed ◽  
Hydrodynamic Performance ◽  
Forward Speed ◽  
Comparative Performance ◽  
Hull Form ◽  
High Speeds ◽  
Head Waves ◽  
Calm Water ◽  
Minimization Algorithms ◽  
Ranse Solver

The hydrodynamic performance of unconventional SWATH and Semi-SWATH for high speed applications are analyzed and compared in this paper. Bare hull resistance in calm water is estimated by an inviscid boundary element method with viscous corrections and verified by a fully turbulent, multiphase unsteady RANSE solver. Motions response in head waves, calculated by a frequency domain 3D panel method with forward speed effects are also evaluated and compared. Both considered hulls are the best designs coming from full parametric hull form optimization procedures, based on CFD solvers for the estimation of their hydrodynamic performance and driven by evolutionary minimization algorithms. The SWATH has twin parabolic struts and an unconventional underwater shape, the semi-SWATH has a slender triangular waterline, a bulbous shape in the entrance body which gradually morph into a U-section with a shallow transom in the run body. In general, as expected, the Semi-SWATH hull shows a lower drag at high speeds while the single strut SWATH is superior at lower speeds. As regards seakeeping, the SWATH shows unbeatable lower pitch and heave motions in shorter waves, where the Semi-SWATH evidences a double peaked RAO. More detailed analysis and conclusion are drawn in the paper.

Numerical Analysis of Planing Boats in Regular and Irregular Head Waves Using a 2D+t Method

2015 ◽  
Author(s):  
Hendrik Haase ◽  
Jan P. Soproni ◽  
Moustafa Abdel-Maksoud
Keyword(s):  
Numerical Analysis ◽  
High Speed ◽  
The State ◽  
Operating Conditions ◽  
Head Waves ◽  
Calm Water ◽  
Rough Water ◽  
Small Craft ◽  
Vertical Accelerations ◽  
Hydrodynamic Evaluation

A large number of small craft with a demand of high speed are planing vessels (Faltinsen, 2005). Their hulls are designed to plane, a condition, in which the boat's weight is carried mainly by hydrodynamic rather than hydrostatic forces. In order to reach the state of stable planing, planing hulls usually have hard chines, a transom stern and a certain deadrise angle, which is often constant in the aft and becomes larger towards the bow. Smaller deadrise angles are associated with a higher dynamic lift, which is often beneficial for the calm water performance. However, smaller deadrise angles also lead to higher vertical accelerations the crew is exposed to when the boat travels in rough water. To ensure good performance in all operating conditions, a hydrodynamic evaluation of the boat's behaviour both in calm water and in waves is important.

scholarly journals Tank Tests with a Scaled Model of a BOC-50 Sailing Yacht Model in Calm Water and in Regular and Random Head Waves

2015 ◽  
Vol 5 (6) ◽  
Author(s):  
Dimitrios Liarokapis ◽  
Konstantina Sfakianaki ◽  
Giannis Papantonatos ◽  
Gregory Grigoropoulos
Keyword(s):  
Scaled Model ◽  
Head Waves ◽  
Calm Water ◽  
Sailing Yacht

A Proposal for Performance Criteria for Propulsion Losses Due to Ship Steering

1982 ◽  
Vol 104 (2) ◽  
pp. 158-165 ◽  
Author(s):  
R. E. Reid
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Relative Performance ◽  
Performance Criteria ◽  
Ship Steering ◽  
Calm Water ◽  
Simulation Results ◽  
Definition Of ◽  
Hydrodynamic Data

The problem of definition of propulsion loss related to ship steering is addressed. Performance criteria representative of propulsion losses due to steering over a range of operating conditions including operation in calm water and a seaway are considered. Criteria are derived from strict analytical considerations and from empirical assumptions based on experimentally derived hydrodynamic data. The applicability of these various criteria and the implications for both assessment of relative performance of existing ship autopilots and for the design of new steering controllers is discussed in relation to simulation results for a high-speed containership.

Experiments and Computations for KCS Added Resistance for Variable Heading

2015 ◽  
Author(s):  
Hamid Sadat-Hosseini ◽  
Serge Toxopeus ◽  
Dong Hwan Kim ◽  
Teresa Castiglione ◽  
Yugo Sanada ◽  
...  
Keyword(s):  
Surface Profile ◽  
Engine Performance ◽  
Head Wave ◽  
Added Resistance ◽  
Local Flow ◽  
Wake Field ◽  
Head Waves ◽  
Calm Water ◽  
Free Surface Profile ◽  
Peak Location

Experiments, CFD and PF studies are performed for the KCS containership advancing at Froude number 0.26 in calm water and regular waves. The validation studies are conducted for variable wavelength and wave headings with wave slope of H/λ=1/60. CFD computations are conducted using two solvers CFDShip-Iowa and STAR-CCM+. PF studies are conducted using FATIMA. For CFD computations, calm water and head wave simulations are performed by towing the ship fixed in surge, sway, roll and yaw, but free to heave and pitch. For variable wave heading simulations, the roll motion is also free. For PF, the ship model moves at a given speed and the oscillations around 6DOF motions are computed for variable wave heading while the surge motion for head waves is restrained by adding a very large surge damping. For calm water, computations showed E<4%D for the resistance,<8%D for the sinkage, and <40%D for the trim. In head waves with variable wavelength, the errors for first harmonic variables for CFD and PF computations were small, <5%DR for amplitudes and <4%2π for phases. The errors for zeroth harmonics of motions and added resistance were large. For the added resistance, the largest error was for the peak location at λ/L=1.15 where the data also show large scatter. For variable wave heading at λ/L=1.0, the errors for first harmonic amplitudes were <17%DR for CFD and <26%DR for PF. The comparison errors for first harmonic phases were E<24%2π. The errors for the zeroth harmonic of motions and added resistance were again large. PF studies for variable wave headings were also conducted for more wavelength condition, showing good predictions for the heave and pitch motions for all cases while the surge and roll motions and added resistance were often not well predicted. Local flow studies were conducted for λ/L=1.37 to investigate the free surface profile and wake field predicted by CFD. The results showed a significant fluctuation in the wake field which can affect the propeller/engine performance. Additionally it was found that the average propeller inflow to the propeller is significantly higher in waves.

NUMERICAL PREDICTION OF VERTICAL SHIP MOTIONS AND ADDED RESISTANCE

2021 ◽  
Vol 159 (A4) ◽  
Author(s):  
F Cakici ◽  
E Kahramanoglu ◽  
A D Alkan
Keyword(s):  
Deep Water ◽  
High Speed ◽  
Computer Experiments ◽  
Navier Stokes ◽  
Ship Motions ◽  
Added Resistance ◽  
Strip Theory ◽  
Head Waves ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method

Along with the development of computer technology, the capability of Computational Fluid Dynamics (CFD) to conduct ‘virtual computer experiments’ has increased. CFD tools have become the most important tools for researchers to deal with several complex problems. In this study, the viscous approach called URANS (Unsteady Reynolds Averaged Navier-Stokes) which has a fully non-linear base has been used to solve the vertical ship motions and added resistance problems in head waves. In the solution strategy, the FVM (Finite Volume Method) is used that enables numerical discretization. The ship model DTMB 5512 has been chosen for a series of computational studies at Fn=0.41 representing a high speed case. Firstly, by using CFD tools the TF (Transfer Function) graphs for the coupled heave- pitch motions in deep water have been generated and then comparisons have been made with IIHR (Iowa Institute of Hydraulic Research) experimental results and ordinary strip theory outputs. In the latter step, TF graphs of added resistance for deep water have been generated by using CFD and comparisons have been made only with strip theory.

An Analysis of Heave Added Mass and Damping of a Surface-Effect Ship

1981 ◽  
Vol 25 (01) ◽  
pp. 44-61
Author(s):  
C. H. Kim ◽  
S. Tsakonas
Keyword(s):  
Free Surface ◽  
High Speed ◽  
Surface Effect ◽  
Practical Method ◽  
Added Mass ◽  
Damping Coefficients ◽  
Calm Water ◽  
Surface Effect Ship ◽  
Long Time ◽  
Computational Procedures

The analysis presents a practical method for evaluating the added-mass and damping coefficients of a heaving surface-effect ship in uniform translation. The theoretical added-mass and damping coefficients and the heave response show fair agreement with the corresponding experimental values. Comparisons of the coupled aero-hydrodynamic and uncoupled analytical results with the experimental data prove that the uncoupled theory, dominant for a long time, that neglects the free-surface effects is an oversimplified procedure. The analysis also provides means of estimating the wave elevation of the free surface, the escape area at the stern and the volume which are induced by a heaving surface-effect ship in uniform translation in otherwise calm water. Computational procedures have been programmed in the FORTRAN IV language and adapted to the PDP-10 high-speed digital computer.

Numerical Prediction of Vertical Ship Motions and Added Resistance

2017 ◽  
Vol 159 (A4) ◽  
Author(s):  
F Cakici ◽  
E Kahramanoglu ◽  
A D Alkan
Keyword(s):  
Deep Water ◽  
High Speed ◽  
Computer Experiments ◽  
Navier Stokes ◽  
Ship Motions ◽  
Added Resistance ◽  
Strip Theory ◽  
Head Waves ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method

Along with the development of computer technology, the capability of Computational Fluid Dynamics (CFD) to conduct ‘virtual computer experiments’ has increased. CFD tools have become the most important tools for researchers to deal with several complex problems. In this study, the viscous approach called URANS (Unsteady Reynolds Averaged Navier-Stokes) which has a fully non-linear base has been used to solve the vertical ship motions and added resistance problems in head waves. In the solution strategy, the FVM (Finite Volume Method) is used that enables numerical discretization. The ship model DTMB 5512 has been chosen for a series of computational studies at Fn=0.41 representing a high speed case. Firstly, by using CFD tools the TF (Transfer Function) graphs for the coupled heave-pitch motions in deep water have been generated and then comparisons have been made with IIHR (Iowa Institute of Hydraulic Research) experimental results and ordinary strip theory outputs. In the latter step, TF graphs of added resistance for deep water have been generated by using CFD and comparisons have been made only with strip theory.

Response Surface Models for Analyzing Planing Hull Motions in a Vertical Plane

2014 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Leonard M. Lye ◽  
Heather Peng
Keyword(s):  
High Speed ◽  
Uniform Design ◽  
Vertical Plane ◽  
Statistical Design ◽  
Surrogate Models ◽  
Center Of Gravity ◽  
Design Parameters ◽  
Strip Theory ◽  
Calm Water ◽  
Sinkage And Trim

A non-linear mathematical model, Planing Hull Motion Program (PHMP) has been developed based on strip theory to predict the heave and pitch motions of planing hull at high speed in head seas. PHMP has been validated against published model test data. For various combinations of design parameters, PHMP can predict the heave and pitch motions and bow and center of gravity accelerations with reasonable accuracy at planing and semi-planing speeds. This paper illustrates an application of modern statistical design of experiment (DOE) methodology to develop simple surrogate models to assess planing hull motions in a vertical plane (surge, heave and pitch) in calm water and in head seas. Responses for running attitude (sinkage and trim) in calm water, and for heave and pitch motions and bow and center of gravity accelerations in head seas were obtained from PHMP based on a multifactor uniform design scheme. Regression surrogate models were developed for both calm water and in head seas for each of the relevant responses. Results showed that the simple one line regression models provided adequate fit to the generated responses and provided valuable insights into the behaviour of planing hull motions in a vertical plane. The simple surrogate models can be a quick and useful tool for the designers during the preliminary design stages.

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