Surface Wave Contours Associated with the Forebody Wake of Stepped Planing Hulls

2010 ◽  
Vol 47 (01) ◽  
pp. 1-16
Author(s):  
Daniel Savistky ◽  
Michael Morabito
Keyword(s):  
Surface Wave ◽  
Model Tests ◽  
Experimental Results ◽  
Empirical Equations ◽  
Stagnation Line

Results of an extensive series of model tests that define the longitudinal surface wake profiles aft of prismatic hulls having deadrise angles of 10º, 20º and 30º are presented. Empirical equations are developed that quantitatively define these profiles and are in a form that can be easily applied by designers of stepped planing hulls. These equations are applicable for an expected range of variations in trim angle, speed coefficient, and loading coefficient typical for these hulls. A brief introduction to the concept and to the hydrodynamic advantages of stepped planing hulls is presented to orient the reader as to the importance of wake data in their design. Examples are presented that illustrate the application of these wake data for stepped planing hulls with wetted forebody chine to achieve maximum hydrodynamic lift/drag ratios. Finally experimental results are presented that illustrate the potential resistance penalty associated with the operation of chines dry forebodies where the stagnation line crosses the step.

Experimental Study of a Tanker Ship Squat in Shallow Water

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
Mohammadreza Fathi Kazerooni ◽  
Mohammad Saeed Seif
Keyword(s):  
Experimental Study ◽  
Shallow Water ◽  
Experimental Approach ◽  
Model Tests ◽  
Ship Hull ◽  
Experimental Results ◽  
Shallow Waters ◽  
Towing Tank ◽  
Ship Model

One of the phenomena restricting the tanker navigation in shallow waters is reduction of under keel clearance in the terms of sinkage and dynamic trim that is called squatting. According to the complexity of flow around ship hull, one of the best methods to predict the ship squat is experimental approach based on model tests in the towing tank. In this study model tests for tanker ship model had been held in the towing tank and squat of the model are measured and analyzed. Based on experimental results suitable formulae for prediction of these types of ship squat in fairways are obtained.

Experimental Assessment of the Performance of CECO Wave Energy Converter in Irregular Waves

2018 ◽  
Author(s):  
Claudio A. Rodríguez ◽  
F. Taveira-Pinto ◽  
P. Rosa-Santos
Keyword(s):  
Wave Energy ◽  
Transfer Functions ◽  
Nonlinear Effects ◽  
Model Tests ◽  
Experimental Results ◽  
Irregular Waves ◽  
Scale Model ◽  
Experimental Assessment ◽  
Simplified Approach ◽  
Wave Basin

A new concept of wave energy device (CECO) has been proposed and developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (FEUP). In a first stage, the proof of concept was performed through physical model tests at the wave basin (Rosa-Santos et al., 2015). These experimental results demonstrated the feasibility of the concept to harness wave energy and provided a preliminary assessment of its performance. Later, an extensive experimental campaign was conducted with an enhanced 1:20 scale model of CECO under regular and irregular long and short-crested waves (Marinheiro et al., 2015). An electric PTO system with adjustable damping levels was also installed on CECO as a mechanism of quantification of the WEC power. The results of regular waves tests have been used to validate a numerical model to gain insight into different potential configurations of CECO and its performance (López et al., 2017a,b). This paper presents the results and analyses of the model tests in irregular waves. A simplified approach based on spectral analyses of the WEC motions is presented as a means of experimental assessment of the damping level of the PTO mechanism and its effect on the WEC power absorption. Transfer functions are also computed to identify nonlinear effects associated to higher waves and to characterize the range of periods where wave absorption is maximized. Furthermore, based on the comparison of the present experimental results with those corresponding to a linear numerical potential model, some discussions are addressed regarding viscous and other nonlinear effects on CECO performance.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

scholarly journals Overtopping of harbour breakwaters: a comparison of semi-empirical equations, neural networks, and physical model tests

2015 ◽  
Vol 53 (4) ◽  
pp. 505-518 ◽  
Author(s):  
Ángeles M. Rodríguez Gil ◽  
José F. Sánchez González ◽  
Ramón Gutiérrez Serret ◽  
Vicente Negro Valdecantos
Keyword(s):  
Neural Networks ◽  
Physical Model ◽  
Model Tests ◽  
Empirical Equations ◽  
Physical Model Tests ◽  
Semi Empirical

scholarly journals Non-Linear Scour Calculator of Skewed Piers

2020 ◽  
Vol 9 (4) ◽  
pp. 1147-1155
Keyword(s):  
Linear Equation ◽  
Experimental Results ◽  
Geometrical Shape ◽  
Empirical Equations ◽  
Shape Factors ◽  
Non Linear Equation ◽  
Non Linear ◽  
The Impact

This paper investigates the impact of skewed piers and their geometrical shape on the scouring. A non-linear equation estimating scour depths around skewed piers (i.e. Piers Scour Calculator PSC) is established experimentally. The rectangular, semicircle and curvilinear piers are investigated. PSC Eq. gives reasonable values compared to formulas of Froechlich (1988), Chitale (1962), Ahmad (1962) and Inglis-Poona (1949). RSQ values equal 92.5%, 83.5% of the training and validating data, respectively. PSC results are convenient with measurements compared to equations of (Richardson & Davis, 2001) and (Melville & Sutherland, 1988). The experimental results showed that values of the scouring parameter 𝒅𝒔 𝒚𝟑 increase by 200%, 270% and 238% for the rectangular, the semicircle, and the curvilinear piers, respectively as the skewed angle increases from 0o to 16.7o . Two empirical equations presenting flow angles and shape factors are developed.

scholarly journals Experimental Test on Bridge Reinforcement by Enlarging Section-Prestress Method

2020 ◽  
Vol 165 ◽  
pp. 04015
Author(s):  
Li Jia ◽  
Liu Tao ◽  
Huang Hong ◽  
Jiang Jian ◽  
Huang Zhi
Keyword(s):  
Bearing Capacity ◽  
Experimental Test ◽  
Ultimate Bearing Capacity ◽  
Model Tests ◽  
Crack Development ◽  
Experimental Results ◽  
Concentrated Load ◽  
External Prestressing ◽  
Rectangular Beam ◽  
Load Characteristics

This paper proposes the method of enlarging section combined with prestressed tendon (Enlarging Section-Prestress Method), which has the advantages of both increasing section and external prestressing, such as reducing section height, the prestressing tendon do not rust easily, and the appearance is beautiful. Model tests were carried out, two rectangular beam models with the same section and length were made, one was reinforced by Enlarging Section-Prestress Method, and no reinforced action was taken as a control. Two points of concentrated load were applied to the model beams, and the two tests were compared in terms of deflection-load characteristics and crack development. The experimental results show that the Enlarging Section-Prestress Method is effective, which improved the ultimate bearing capacity of the beam obviously, and reduced the deflection of the trabecular beam.

PERFORMANCE VARIATIONS OF A CABLE-STAYED BRIDGE WITH DAMAGED CABLES

2013 ◽  
Vol 13 (05) ◽  
pp. 1250083 ◽  
Author(s):  
OU YANG ◽  
HUI LI ◽  
JINPING OU ◽  
Q. S. LI
Keyword(s):  
Yellow River ◽  
Dynamic Performance ◽  
Element Model ◽  
Model Tests ◽  
Experimental Results ◽  
Detailed Model ◽  
Cable Stayed Bridge ◽  
Bridge Model ◽  
Internal Forces ◽  
Cable Damage

A cable-stayed bridge model was made based on the design drawings of Shandong Binzhou Yellow River Highway Bridge (BZB) and detailed model tests were conducted. In the tests, the cable damage effects on the loading behavior and dynamic performance of the bridge model were studied by considering different cable damages' locations, different numbers of damaged cables, and different damaged levels of cables etc. The experimental results revealed that the cable damages may significantly affect the internal forces of other cables and the stress distributions of the girders; however, they have less influence on the natural frequencies of the bridge model. In parallel with the model tests, a finite element model of the bridge structure has been established. Numerical analysis for the bridge model with cable damages was carried out to validate the experimental results and explain the phenomena observed in the model tests.

scholarly journals Experimental Study on the Influence of Berms and Roughness on Wave Overtopping at Rock-Armoured Dikes

2020 ◽  
Vol 8 (6) ◽  
pp. 446 ◽  
Author(s):  
Weiqiu Chen ◽  
Alberto Marconi ◽  
Marcel R. A. van Gent ◽  
Jord J. Warmink ◽  
Suzanne J. M. H. Hulscher
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Physical Model ◽  
Model Tests ◽  
Empirical Equations ◽  
Wave Overtopping ◽  
Dissipation Of Energy ◽  
Physical Model Tests ◽  
Weighting Coefficients

The average overtopping discharge is an important parameter for the design and reinforcement of dikes. Rock armour on the waterside slopes and berms of dikes is widely used to reduce the wave overtopping discharge by introducing slope roughness and dissipation of energy in the permeable armour layer. However, methods for estimating the influence of a rock berm and roughness of rock armour at dikes on the average overtopping discharge still need to be developed and/or validated. Therefore, this study aims to develop empirical equations to quantify the reductive influence of rock armour on wave overtopping at dikes. Empirical equations for estimating the effects of rock berms and roughness are derived based on the analysis of experimental data from new physical model tests. The influence of roughness of the rock armour applied on parts of waterside slopes is estimated by introducing the location weighting coefficients. Results show that the newly derived equations to predict the average overtopping discharge at dikes lead to a significantly better performance within the tested ranges compared to existing empirical equations.

scholarly journals Research on Polarization Cancellation of Nonstationary Ionosphere Clutter in HF Radar System

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Xingpeng Mao ◽  
Hong Hong ◽  
Weibo Deng ◽  
Yongtan Liu
Keyword(s):  
Surface Wave ◽  
Time Domain ◽  
High Frequency ◽  
Interference Cancellation ◽  
Radar System ◽  
Experimental Results ◽  
Hf Radar ◽  
Oblique Projection ◽  
Polarization Filter ◽  
Wave Radar

Oblique projection polarization filter (OPPF) can be applied as an effective approach for interference cancellation in high-frequency surface wave radar (HFSWR) and other systems. In order to suppress the nonstationary ionosphere clutter further, a novel OPPF based clutter suppressing scheme is proposed in this paper. The polarization and nonstationary characteristic of the clutter are taken into account in the algorithms referred to as range-Doppler domain polarization suppression (RDDPS) and the range-time domain polarization suppression (RTDPS) method, respectively. The RDDPS is designed for weak ionosphere clutter and implemented in the range-Doppler domain directly, whereas the RTDPS algorithm is designed to suppress the powerful ionosphere clutter with a multisegment estimation and suppression scheme. About 15–23 dB signal to interference ratio (SIR) improvement can be excepted when using the proposed method, whereas the targets can be more easily detected in the range-Doppler map. Experimental results demonstrate that the scheme proposed is effective for nonstationary ionosphere clutter and is proven to be a practical interference cancellation technique for HFSWR.

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