Hydrodynamics of High-Speed Planing Craft: Savitsky Method and 2D+t Approach

2021 ◽  
Author(s):  
M. Javad Javaherian ◽  
Richard Royce ◽  
Raju Datla ◽  
Christine M. Gilbert
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Hydrodynamic Force ◽  
Prediction Method ◽  
Water Entry ◽  
Planing Craft ◽  
Towing Tank ◽  
Entry Model ◽  
Calm Water

The progressive interest in high-speed planing craft has made it crucial to conduct more accurate assessments of the behavior of these vessels in motion. In this paper, a 2D+t approach is employed to predict the resistance, trim and wetted length of a prismatic planing craft cruising in calm water. Although this approach is based on original Zarnick 2D+t model, the hydrodynamic force is estimated using experimental wedge drop experiments in conjunction with the Logvinovich wedge water entry model. The analysis is repeated employing Savitsky prediction method and results are compared with that of towing tank measurements of Naples series. The comparison shows that the Savitsky prediction results match very well with the experimental data. The 2D+t approach also shows reasonable outcomes for the trim and wetted length. However, this approach slightly underestimates the resistance of the craft at very low Froude numbers.

On the Water-Entry-Induced Cavity Closure for a Wide Range of Entry Speeds

2003 ◽  
Vol 125 (5) ◽  
pp. 927-930 ◽  
Author(s):  
M. Lee
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Water Entry ◽  
Ambient Atmosphere ◽  
Important Research ◽  
Atmosphere Pressure ◽  
Research Areas ◽  
Wide Range ◽  
Entry Speed ◽  
Cavity Closure

One of the important research areas in the water-entry problem is the cavity dynamics. A theoretical analysis is presented to predict the dynamics of water-entry cavity up to the first cavity closure, which is generated by a solid body entering a semi-inifinite free surface of water at a wide range of entry speed. Two types of cavity closure, which are surface closure and the deep closure, depending on the magnitude of ambient atmosphere pressure and entry speed are described by the proposed theory. The time of surface closure at the relatively low-speed entry regime is estimated and compared with published experimental data. Currently no experimental data are available for the high-speed entry case.

Comparisons Between Prediction and Experiment for Lift Force and Heel Moment for a Planing Hull

2013 ◽  
Vol 29 (01) ◽  
pp. 36-46
Author(s):  
Carolyn Q. Judge
Keyword(s):  
High Speed ◽  
Lift Force ◽  
Forward Speed ◽  
Dynamic Effects ◽  
Planing Craft ◽  
Underwater Photography ◽  
Calm Water ◽  
Transverse Stability ◽  
The Relationship ◽  
Righting Moment

Even in calm water, high-speed vessels can display unstable behaviors such chine walking, sudden large heel, and porpoising. Large heel results from the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water. The available righting moment resulting from the hydrostatic buoyancy is, therefore, reduced. As the righting moment resulting from hydrostatic buoyancy is reduced, the righting moment resulting from dynamic effects becomes important. These hydrodynamic righting effects are related to the hydrodynamic lift. This article explores the relationship between the hydrostatic lift and righting moment, the hydrodynamic lift and righting moment, and the total lift and heel-restoring moment of a planing craft operating at planing speeds. A series of tow tests using a prismatic hull with a constant deadrise of 20 measured the lift force and righting moment at various angles of heel and at various model velocities. The model was completely constrained in surge, sway, heave, roll, pitch, and yaw. The underwater volume is determined from the known hull configuration and the underwater photography of the keel and chine wetted lengths. The results presented include the total lift and righting moment with the hydrostatic and hydrodynamic contributions for various model speeds at two model displacements.

Numerical Simulation of Dynamic Response of Planing Craft Sailing in Calm Water

2014 ◽  
Vol 590 ◽  
pp. 37-41
Author(s):  
Yu Min Su ◽  
Yun Hui Li ◽  
Hai Long Shen
Keyword(s):  
Numerical Simulation ◽  
Empirical Formula ◽  
High Speed ◽  
Evaluation Method ◽  
Simulation Method ◽  
Experimental Results ◽  
Planing Craft ◽  
Calm Water ◽  
Performance Evaluation Method ◽  
Good Agreement

In order to forecast the sailing response of planing craft at high speed rapidly and accurately, CFD code Fine/Marine solver was used to calculate the resistance and sailing attitude of a high-speed planing craft, then the numerical results were compared with experimental results and empirical formula results. The results showed that resistance error calculated by Fine/Marine was between 5% and 10%, trim and heave results were in good agreement with experimental results, and had greater accuracy compared with the empirical formula results. The feasibility of this numerical simulation method was validated and this method provided an effect performance evaluation method for new designing planing crafts.

Empirical Methods for Predicting Lift and Heel Moment for a Heeled Planing Hull

2014 ◽  
Vol 30 (04) ◽  
pp. 175-183
Author(s):  
Carolyn Q. Judge
Keyword(s):  
High Speed ◽  
Experimental Program ◽  
Naval Academy ◽  
Forward Speed ◽  
Empirical Methods ◽  
Empirical Relationships ◽  
Planing Craft ◽  
Underwater Photography ◽  
Calm Water ◽  
Transverse Stability

Even in calm water, high-speed vessels can display unstable behaviors such as chine walking, sudden large heel, and porpoising. Large heel angle can result in the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water, reducing the underwater geometry. An experimental program at the U.S. Naval Academy has been designed to investigate the transverse stability of planing hulls. An experimental mechanism to force a planing hull model in heave and roll motion was designed and built. The first model tested was a wooden prismatic planing hull model with a constant deadrise of 20, a beam of 1.48 ft (0.45 m), and a total length of 5 ft (1.52 m). The model was held at various heel and running draft positions while fixed in pitch, yaw, and sway. The tests were done at two model speeds, for one model displacement, five fixed heel angles, and five fixed running heave positions. The lift and sway forces, along with the heel moment, were measured and underwater photography was taken of the wetted surface. This article presents a set of equations based on empirical relationships for calculating the lift and heel moment for a prismatic planing hull at nonzero heel angles.

scholarly journals An experimental study of interceptor’s effectiveness on hydrodynamic performance of high-speed planing crafts

2013 ◽  
Vol 20 (2) ◽  
pp. 21-29 ◽  
Author(s):  
Mohammad Hosein Karimi ◽  
Mohammad Saeed Seif ◽  
Madjid Abbaspoor
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Hydrodynamic Performance ◽  
Control Mechanisms ◽  
Towing Tank ◽  
University Of Technology ◽  
Speed Range ◽  
Calm Water ◽  
Wide Speed Range ◽  
The Impact

Abstract Trim control mechanisms such as interceptors and trim flaps have been widely used in recent years in highspeed crafts for ride and trim control. In spite of their extensive application, a few studies investigating the impact of interceptors on planing craft performance, have been published. In the present study, the impact of interceptors on planing crafts hydrodynamic quality is investigated through application of an experimental method. Two scaled-down models of high-speed planing mono-hull and catamaran are tested with and without interceptors in calm water at different heights of the interceptors to investigate the effect of interceptors on drag reduction of the models. The first one is a scaled-down model of 11 m planing mono-hull boat and the test was conducted at the towing tank of Sharif University of Technology, Iran. The second one is a scaled-down model of 18 m planing catamaran boat and the test was conducted at the towing tank of Krylov Shipbuilding Research Institute (KSRI), Russia. The experimental results show a remarkable drag reduction of up to 15% for mono-hull model and up to 12% for catamaran model over the wide speed range of the models.

Effect of Spray-Strake on Patrol Vessel Manoeuvrability

2008 ◽  
Author(s):  
Andi Haris Muhammad ◽  
Adi Maimun ◽  
Omar Yaakob ◽  
Agoes Priyanto
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Design Method ◽  
Towing Tank ◽  
Water Condition ◽  
Calm Water ◽  
Planing Vessel

This paper describes a design method on the spray-strake parameters of a planing hull (patrol vessel) based on manoeuvring performance in calm water condition. The method set a spray-strake mathematical model which has been developed using experimental data from towing tank. The model selects such a spray-strake parameter which has the effects on manoeuvrability characteristics. In showing these effects, some IMO manoeuvring (for turning circle and zigzag manoeuvre) have been simulated for a planing hull with the designated spray-strake parameter. The results indicate that the spray-strakes attached to the planing vessel have effects on its manoeuvring performance.

Experimental and numerical analyses of wedge effects on the rooster tail and porpoising phenomenon of a high-speed planing craft in calm water

2019 ◽  
Vol 233 (13) ◽  
pp. 4637-4652 ◽  
Author(s):  
Sayyed Mahdi Sajedi ◽  
Parviz Ghadimi ◽  
Mohammad Sheikholeslami ◽  
Mohammad A Ghassemi
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Scale Model ◽  
Test Cases ◽  
Planing Craft ◽  
Calm Water ◽  
Space Discretization ◽  
Good Agreement

This paper presents experimental and numerical investigation of stability and rooster tail of a mono-hull high-speed planing craft with a constant deadrise angle. Initially, a one-fifth scale model was tested in a towing tank, which showed porpoising phenomenon at 8 m/s (equal to the speed of sailing). Subsequently, two wedges of 5 and 10 mm heights, based on the boundary layer calculations, were mounted on the aft section of the planing hull. These wedges were shown to increase the lift at the aft section. These experiments were carried out at different speeds up to 10 m/s in calm water. The experimental results indicated that the installed wedges reduced the trim, drag, and the elapsed time for reaching the hump peak, and also eliminated the porpoising condition. All these test cases were also numerically simulated using Star CCM+ software. The free surface was modeled using the volume of fluid scheme in three-dimensional space. The examined planing craft had two degrees of freedom, and overset mesh technique was used for space discretization. The obtained numerical results were compared with experimental data and good agreement was displayed in the presented comparisons. Ultimately, the effect of the wedge on the rooster tail behind the planing craft was studied. The results of this investigation showed that by decreasing the trim at a constant speed, the height of the generated wake profile (rooster tail) behind the craft decreases, albeit its length increases.

The Design of High Speed Planing Craft Using an Optimization Framework

2012 ◽  
Author(s):  
Warren F. Smith ◽  
Ahmad F. Mohamad Ayob ◽  
Tapabrata Ray
Keyword(s):  
High Speed ◽  
Design Space Exploration ◽  
Population Based ◽  
Planing Craft ◽  
Optimization Framework ◽  
Trade Offs ◽  
Life Saving ◽  
Calm Water ◽  
Domain Independent

High speed planing craft as a unique vessel type play key commercial roles in niche passenger ferrying and high value cargo transport. In addition, they are used to support several critical maritime activities such as coastal surveillance, reconnaissance, and life-saving operations and many recreational pursuits. Formal optimization frameworks, despite their significant use across a range of domains, have rarely been proposed and developed to deal with the design challenges of high speed planing craft. Highlighted in this paper is an optimization framework drawing on both domain dependent and domain independent elements for the conceptual and preliminary design of high speed planing craft. A summary of the principal components of the optimization framework are presented, followed by several case study examples. The solvers developed and employed are classified as being population based, evolutionary and stochastic in nature. These characteristics are well suited to design space exploration in all engineering and decision making contexts. Within the case studies presented, the sample key performance indicators include calm water resistance, resistance in waves, seakeeping and manoeuvring. The concept of scenario-based hydrodynamic design optimization is introduced using an example of a small rescue craft operating in a predefined sea-state. Finally, a multi-objective optimization case study considering total resistance, steady turning diameter and vertical impact acceleration is presented to demonstrate the capability to explore trade-offs while at the same time providing an understanding of the design intent of a basis ship. This work has significant purpose and relevance in both ab-initio and reverse engineering contexts. It also has natural extensions in both depth of analysis and breadth of application.

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