Seaway Load Prediction Algorithms for High Speed Hull Forms

2005 ◽  
Author(s):  
Jerome P. Sikora ◽  
Nathan B. Klontz
Keyword(s):  
High Speed ◽  
Scaling Laws ◽  
Surface Effect ◽  
Concept Design ◽  
Load Prediction ◽  
Design Studies ◽  
Prediction Algorithms ◽  
Scale Test ◽  
Hull Forms ◽  
Computational Analyses

This paper documents the generation of several seaway load prediction algorithms for catamarans, trimarans, and surface effect ships based on available model and full-scale test data. Froude scaling laws are used for geometrically different ships for each ship and load type using first principles and empirically derived studies. Simple seaway load prediction algorithms are then developed and expressed as functions of ship displacement and various key ship particulars. These global load algorithms are quickly computed, making them suitable for preliminary or concept design studies. In some cases, algorithms were developed from a minimum amount of data, and it is anticipated that as more data is gathered in the future, these algorithms will be further refined. As the ship design progresses, more accurate but time consuming computational analyses and model tests are appropriate.

Concept Exploration of a Surface Effect Patrol Combatant Using a Multiobjective Synthesis Model

2021 ◽  
Author(s):  
Harry P. Crosby ◽  
Katherine E. Zalegowski ◽  
Raphael Christian C. Batto
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Optimization Techniques ◽  
Concept Design ◽  
Highly Nonlinear ◽  
Concept Exploration ◽  
3D Geometry ◽  
Objective Space ◽  
Surface Combatant ◽  
And Performance

This paper demonstrates a concept design methodology for naval SESs that is adapted from modern surface combatant optimization techniques. Similar to current methods, a synthesis model is constructed that uses a variety of discrete and continuous input values to calculate ship characteristics and performance data. The model outputs are generated using a combination of first-principles and exact 3D geometry along with parametrics aggregated from conventional monohulls and SES historical data. A specifically formulated multiobjective genetic algorithm is integrated with the model. The algorithm explores the highly nonlinear and non-convex SES objective space to identify non-dominated design variants. The synthesis model and the associated design space for a patrol boat with a novel SES hullform is detailed. Tradeoffs are evaluated in objective criteria of cost and performance in high-speed littoral operations that include surveillance, reconnaissance, and surface warfare.

scholarly journals Predicting specific impulse distributions for spherical explosives in the extreme near-field using a Gaussian function

2021 ◽  
pp. 204141962199349
Author(s):  
Jordan J Pannell ◽  
George Panoutsos ◽  
Sam B Cooke ◽  
Dan J Pope ◽  
Sam E Rigby
Keyword(s):  
Scaling Laws ◽  
Near Field ◽  
Specific Impulse ◽  
Gaussian Function ◽  
Data Driven ◽  
Blast Load ◽  
Structural Deformation ◽  
Load Prediction ◽  
Validation Data ◽  
Wide Range

Accurate quantification of the blast load arising from detonation of a high explosive has applications in transport security, infrastructure assessment and defence. In order to design efficient and safe protective systems in such aggressive environments, it is of critical importance to understand the magnitude and distribution of loading on a structural component located close to an explosive charge. In particular, peak specific impulse is the primary parameter that governs structural deformation under short-duration loading. Within this so-called extreme near-field region, existing semi-empirical methods are known to be inaccurate, and high-fidelity numerical schemes are generally hampered by a lack of available experimental validation data. As such, the blast protection community is not currently equipped with a satisfactory fast-running tool for load prediction in the near-field. In this article, a validated computational model is used to develop a suite of numerical near-field blast load distributions, which are shown to follow a similar normalised shape. This forms the basis of the data-driven predictive model developed herein: a Gaussian function is fit to the normalised loading distributions, and a power law is used to calculate the magnitude of the curve according to established scaling laws. The predictive method is rigorously assessed against the existing numerical dataset, and is validated against new test models and available experimental data. High levels of agreement are demonstrated throughout, with typical variations of <5% between experiment/model and prediction. The new approach presented in this article allows the analyst to rapidly compute the distribution of specific impulse across the loaded face of a wide range of target sizes and near-field scaled distances and provides a benchmark for data-driven modelling approaches to capture blast loading phenomena in more complex scenarios.

Curved surface effect on high-speed droplet impingement

2020 ◽  
Vol 909 ◽  
Author(s):  
Wangxia Wu ◽  
Qingquan Liu ◽  
Bing Wang
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Curved Surface ◽  
Droplet Impingement

Abstract

Splash formation by spherical drops

2001 ◽  
Vol 427 ◽  
pp. 73-105 ◽  
Author(s):  
LIOW JONG LENG
Keyword(s):  
High Resolution ◽  
Quantitative Data ◽  
Water Surface ◽  
High Speed ◽  
Scaling Laws ◽  
Capillary Wave ◽  
Water Drop ◽  
Qualitative And Quantitative ◽  
High Resolution Images ◽  
The Impact

The impact of a spherical water drop onto a water surface has been studied experimentally with the aid of a 35 mm drum camera giving high-resolution images that provided qualitative and quantitative data on the phenomena. Scaling laws for the time to reach maximum cavity sizes have been derived and provide a good fit to the experimental results. Transitions between the regimes for coalescence-only, the formation of a high-speed jet and bubble entrapment have been delineated. The high-speed jet was found to occur without bubble entrapment. This was caused by the rapid retraction of the trough formed by a capillary wave converging to the centre of the cavity base. The converging capillary wave has a profile similar to a Crapper wave. A plot showing the different regimes of cavity and impact drop behaviour in the Weber–Froude number-plane has been constructed for Fr and We less than 1000.

Optimum Structural Design of High-Speed Surface Effect Ships Built of Composite Materials

2003 ◽  
Vol 40 (01) ◽  
pp. 42-48
Author(s):  
Chang Doo Jang ◽  
Ho Kyung Kim ◽  
Ha Cheol Song
Keyword(s):  
Composite Materials ◽  
Computer Program ◽  
Structural Design ◽  
High Speed ◽  
Surface Effect ◽  
Minimum Weight ◽  
Original Design ◽  
Optimum Structural Design ◽  
Surface Effect Ship ◽  
Speed Performance

A surface effect ship is known to be comparable to a high-speed ship. For the structural design of surface effect ships, advanced design methods are needed which can reflect the various loading conditions different from those of conventional ships. Also, minimum weight design is essential because hull weight significantly affects the lift, thrust powering and high-speed performance. This paper presents the procedure of optimum structural design and a computer program to minimize the hull weight of surface effect ships built of composite materials. By using the developed computer program, the optimum structural designs for three types of surface effect ships—built of sandwich plate only, stiffened single skin plate only, and both plates—are carried out and the efficiency of each type is investigated in terms of weight. The computer program, developed herein, successfully reduced the hull weight of surface effect ships by 15–30% compared with the original design. Numerical results of optimum structural designs are presented and discussed.

The Basiliscus Project - Return of the Cruising Hydrofoil Sailboat

2001 ◽  
Author(s):  
Thomas E. Speer
Keyword(s):  
Scaling Laws ◽  
Development Plan ◽  
Cfd Modeling ◽  
Design Studies ◽  
Baseline Design

Basiliscus will be a cruising hydrofoil sailboat, much along the lines of David Keiper's Williwaw, but incorporating experience that has been gained in multihull design in the thirty years since Williwaw's construction. This paper covers the development plan for the entire project and the technical results of design studies performed to date. Topics covered include scaling laws for model hydrofoils, the baseline design, and preliminary CFD modeling of the hydrofoils.

Resistance Predictions for Asymmetrical Configurations of High-Speed Catamaran Hull Forms

2015 ◽  
Author(s):  
Srikanth Asapana ◽  
Prasanta K. Sahoo ◽  
Vaibhav Aribenchi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Comparative Analysis ◽  
High Speed ◽  
Public Domain ◽  
Literature Survey ◽  
Historical Background ◽  
Resistance Analysis ◽  
Separation Ratio ◽  
Hull Forms

This paper attempts to undertake a comparative analysis of resistance characteristics between newly developed asymmetrical catamaran hull forms which were derived from existing conventional NPL series of round bilge catamaran hull forms by Molland, Wellicome and Couser (1994). A set of asymmetrical catamaran hull forms with waterline length of 1.6 m with a separation ratio (s/L) of 0.4 were generated by using standard modelling software. The resistance analysis had been carried out by using STAR CCM+, a computational fluid dynamics package for Froude numbers of 0.25, 0.30, 0.60, 0.80 and 1.0. Literature survey indicates that there is scant historical background in public domain to perform resistance analysis on asymmetrical catamaran hull forms. As this is not feasible due to lack of data in areas that were considered crucial, separate resistance analysis is carried out for each hull configuration. Finally, the compared resistance results will attempt to conclude whether asymmetrical catamaran hull forms are more efficient than the conventional catamaran hull forms.

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