scholarly journals A CFD Study of the Resistance Behavior of a Planing hull in Restricted Waterways

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Ahmed O. Elaghbash
Keyword(s):  
Shallow Water ◽  
High Speed ◽  
Lift Force ◽  
Critical Speed ◽  
Wave Pattern ◽  
Numerical Results ◽  
Experimental Results ◽  
Total Resistance ◽  
Computational Fluid Dynamics Analysis ◽  
Speed Range

The demand for high-speed boats that operating near to shoreline is increasing nowadays. Understanding the behavior and attitude of high-speed boats when moving in different waterways are very important for boat designer. Usually, they using experimental model testing for resistance prediction and dynamic force but this method is high consuming time, and cost. When planing boats are moving at high speed, two forces participate in their support, they are the hydrodynamic lift created by the shape of the planing hull, and the lift force resulting from displacing part of the liquid (buoyancy force).This research uses a CFD (Computational Fluid Dynamics) analysis to investigate the shallow water effects on prismatic planing hull. The turbulence flow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛ turbulence model. The free surface was modelled by the volume of fluid (VOF) method. The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh =0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range. For this fluctuation in the results, the average numerical value of the results was taken to compare it with the experiment.In this study, the planing hull lift force, total resistance, and wave pattern for the range of subcritical speeds, critical speeds, and supercritical speeds have been calculated using CFD. The numerical results have been compared with experimental results. The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water.The numerical results give a good agreement with the experimental results whereas total average error equals 7% for numerical lift force, and 8% for numerical total resistance. The worst effect on the planing hull in shallow channels occurs at the critical speed range, where solitary wave formulates.

Computer Aided Resistance Prediction Of High Speed Planing Hull Forms

1994 ◽  
pp. 23-43
Author(s):  
Mohd. Ramzan Mainal
Keyword(s):  
High Speed ◽  
Computational Procedure ◽  
Model Testing ◽  
Experimental Results ◽  
Total Resistance ◽  
Computer Prediction ◽  
Computer Aided ◽  
Tremendous Amount ◽  
Resistance Prediction ◽  
Hull Forms

Planing crafts have been the traditional solution to high speed at sea. However, the limitations on high speed planing hull forms in a seaway have led to a tremendous amount of work currently being carried out on hydrofoils, catamarans and hybrid crafts. Despite these facts, the warship, commercial and pleasure markets still show demands for planing crafts and many new designs appear every year. The objective of this paper is to develop a computational procedure for predicting the total resistance of hard chine planing hull forms, prior to model testing. The computer prediction is later validated with existing experimental results.

scholarly journals Hull Forms of High Speed Craft having smallest Total Resistance at High Speed Range

1976 ◽  
Vol 1976 (140) ◽  
pp. 51-57
Author(s):  
Yasushi Yoshida ◽  
Hirotsugu Tanaka ◽  
Tamotsu Nagai
Keyword(s):  
High Speed ◽  
Total Resistance ◽  
Speed Range ◽  
Hull Forms

Critical Speeds, Divergence, and Flutter Instability in High-Speed Planetary Gears

2012 ◽  
Author(s):  
Christopher G. Cooley ◽  
Robert G. Parker
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Numerical Results ◽  
Planetary Gears ◽  
Critical Speeds ◽  
Flutter Instability ◽  
Divergence Instability ◽  
Translational Mode

The structured properties of the critical speeds and associated critical speed eigenvectors of high-speed planetary gears are given. Planetary gears have only planet, rotational, and translational mode critical speeds. Divergence instability is possible at speeds adjacent to critical speeds. Numerical results verify the critical speed locations. Divergence and flutter instabilities are investigated numerically for each mode type.

Paper 4: Synchronous Whirling of a Shaft within a Radially Flexible Annulus Having Small Radial Clearance

1966 ◽  
Vol 181 (1) ◽  
pp. 65-73 ◽  
Author(s):  
H. F. Black
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Surface Friction ◽  
Cumulative Effects ◽  
Radial Clearance ◽  
Stiffness Ratio ◽  
Centrifugal Pumps ◽  
Mass Eccentricity ◽  
Speed Range ◽  
Annular Clearance

Where it is intended to run the shaft at high speed—that is, above the first critical speed—contact between the shaft and annulus may take place in running up to speed just below the critical speed if the mass eccentricity is sufficient in relation to the damping. It is shown that such contact can radically alter the high-speed behaviour of the shaft over a speed range possibly extending to several times the critical speed. In this range, synchronous whirling can take place at a radius exceeding the annular clearance. The whirl radius in this condition may attain between ten and one hundred times the magnitude expected in normal high-speed running at the same speed. The dependence of magnitude and range of this type of whirling on annulus to shaft stiffness ratio, damping and surface friction is examined: the conditions for stability of equilibrium are theoretically examined. The essential features of the theory have been tested on a laboratory rig; some typical results are given. There is some evidence that this type of whirling can occur in centrifugal pumps, the cumulative effects leading to failure.

scholarly journals High Speed Wave Pattern on Shallow Water Surface

1962 ◽  
Vol 10 (96) ◽  
pp. 1-7
Author(s):  
D. MANABE ◽  
H. OHIRA ◽  
K. KAWATATE ◽  
S. NISHIMOTO
Keyword(s):  
Shallow Water ◽  
Water Surface ◽  
High Speed ◽  
Wave Pattern

scholarly journals Numerical Investigation of the Resistance of a Zero-Emission Full-Scale Fast Catamaran in Shallow Water

2021 ◽  
Vol 9 (6) ◽  
pp. 563
Author(s):  
Guangyu Shi ◽  
Alexandros Priftis ◽  
Yan Xing-Kaeding ◽  
Evangelos Boulougouris ◽  
Apostolos D. Papanikolaou ◽  
...  
Keyword(s):  
Shallow Water ◽  
Froude Number ◽  
Deep Water ◽  
Critical Speed ◽  
Full Scale ◽  
Maximum Pressure ◽  
Total Resistance ◽  
Continuous Increase ◽  
Zero Emission ◽  
Pressure Resistance

This paper numerically investigates the resistance at full-scale of a zero-emission, high-speed catamaran in both deep and shallow water, with the Froude number ranging from 0.2 to 0.8. The numerical methods are validated by two means: (a) Comparison with available model tests; (b) a blind validation using two different flow solvers. The resistance, sinkage, and trim of the catamaran, as well as the wave pattern, longitudinal wave cuts and crossflow fields, are examined. The total resistance curve in deep water shows a continuous increase with the Froude number, while in shallow water, a hump is witnessed near the critical speed. This difference is mainly caused by the pressure component of total resistance, which is significantly affected by the interaction between the wave systems created by the demihulls. The pressure resistance in deep water is maximised at a Froude number around 0.58, whereas the peak in shallow water is achieved near the critical speed (Froude number ≈ 0.3). Insight into the underlying physics is obtained by analysing the wave creation between the demihulls. Profoundly different wave patterns within the inner region are observed in deep and shallow water. Specifically, in deep water, both crests and troughs are generated and moved astern as the increase of the Froude number. The maximum pressure resistance is accomplished when the secondary trough is created at the stern, leading to the largest trim angle. In contrast, the catamaran generates a critical wave normal to the advance direction in shallow water, which significantly elevates the bow and creates the highest trim angle, as well as pressure resistance. Moreover, significant wave elevations are observed between the demihulls at supercritical speeds in shallow water, which may affect the decision for the location of the wet deck.

The Bifurcation Analysis of High-Speed Vehicle and Mechanism of Jumping Rail

2007 ◽  
Author(s):  
Wei Wang ◽  
Guixian Li ◽  
Guangbin Yu
Keyword(s):  
Bifurcation Diagram ◽  
Bifurcation Analysis ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Critical Speed ◽  
New Method ◽  
Speed Range ◽  
Nonlinear Relation ◽  
Multi Body ◽  
High Speed Vehicle

The dynamics phenomena of half railway carriage model with 17 degrees of freedom are investigated. The model is set to run on a straight track with the speed range between 85 and 165m/s. Shen-Hedrick-Elkins theory is used to describe the nonlinear relation between the creepage and the creep forces. A new method of flange contact as multi-body collision is also presented. Bifurcation diagram and the critical speed for jumping rail are obtained and further validated by the simulation. Finally, the phase plots of the flange contact are discussed.

scholarly journals Numerical Investigation of the Full-Scale Resistance of a Zero-Emission Fast Catamaran in Shallow Water

2021 ◽  
Author(s):  
Guangyu Shi ◽  
Alexandros Priftis ◽  
Yan Xing-Kaeding ◽  
Evangelos Boulougouris ◽  
Apostolos Papanikolaou ◽  
...  
Keyword(s):  
Shallow Water ◽  
Froude Number ◽  
Deep Water ◽  
Critical Speed ◽  
Full Scale ◽  
Maximum Pressure ◽  
Total Resistance ◽  
Continuous Increase ◽  
Zero Emission ◽  
Pressure Resistance

The present paper investigates numerically the resistance at full-scale of a zero-emission, high-speed catamaran in both deep and shallow water, with the Froude number ranging from 0.2 to 0.8. The numerical methods are validated by two means: a) comparison with available model tests; b) a blind validation using two different flow solvers. The resistance, sinkage and trim of the catamaran, as well as the wave pattern, longitudinal wave cuts and cross-flow fields, are examined. The total resistance curve in deep water shows a continuous increase with the Froude number while in shallow water, a hump is witnessed near the critical speed. This difference is mainly caused by the pressure component of total resistance, which is significantly affected by the interaction between the wave systems created by the demihulls. The pressure resistance in deep water is maximised at a Froude number around 0.58, whereas the peak in shallow water is achieved near the critical speed (Froude number ≈ 0.3). Insight into the underlying physics is obtained by analysing the wave creation between the demihulls. Profoundly different wave patterns within the inner region are observed in deep and shallow water. Specifically, in deep water, both crests and troughs are generated and moved astern as the increase of the Froude number. The maximum pressure resistance is accomplished when the secondary trough is created at the stern, leading to the largest trim angle. In contrast, the catamaran generates a critical wave normal to the advance direction in shallow water, which significantly elevates the bow and creates the highest trim angle as well as pressure resistance. Moreover, significant wave elevations are observed between the demihulls at supercritical speeds in shallow water which may affect the decision for the location of the wet deck.

scholarly journals Effect of the Addition of Hydrofoil on Lift Force and Resistance in 60 M High-Speed Vessel

Kapal ◽  
2020 ◽  
Vol 17 (3) ◽  
pp. 95-106
Author(s):  
Izzuddin Nadzir Ismail ◽  
Parlindungan Manik ◽  
Mahendra Indiaryanto
Keyword(s):  
Froude Number ◽  
Computational Fluid Dynamic ◽  
High Speed ◽  
Lift Force ◽  
Fluid Dynamic ◽  
Model Analysis ◽  
Total Resistance ◽  
High Speeds ◽  
Sea Transportation ◽  
Resistance Value

The development of sea transportation technology is needed to meet the demand for ships that can carry heavier loads and operate at high speeds. Modifications in the form of additional hydrofoil variations were conducted to produce higher lift and reduce the resistance generated by the ship so that the ship can go more efficiently at high speed. This study aims to obtain the effect of adding hydrofoil to ships with variations in the type and shape of foil and find out which types and shapes can reduce resistance on the ship. This research was conducted with several model analysis tests using Computational Fluid Dynamic (CFD) based software, namely Tdyn, at several different speeds. The results of this study show that of the six variation models analyzed, rectangular fully submerged foil models can reduce the total resistance value of the ship by 17.822% from the original ship on Froude Number (Fr) 0.670. The type and shape of the foil is very influential on the lift and resistance produced by the ship.

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