Ship – model correlation of five similar cross-channel twin-screw motor ships

1969 ◽  
Vol 16 (179) ◽  
pp. 205-211
Author(s):  
G. Aertssen
Keyword(s):  
Ship Model ◽  
Twin Screw ◽  
Model Correlation

Paper 11. Yaw Motion Stability; Twin-Screw, Twin-Rudder Ships—Some Model and Ship Results

1972 ◽  
Vol 14 (7) ◽  
pp. 75-79
Author(s):  
G. D. Thurman
Keyword(s):  
Model Test ◽  
Model Tests ◽  
Full Scale ◽  
Test Results ◽  
Motion Stability ◽  
Ship Model ◽  
Pull Out ◽  
Twin Screw ◽  
Model Correlation ◽  
Stability Results

This paper describes the pull-out manoeuvre as an indication of yaw motion stability. Results of model tests at the Admiralty Experiment Works and full-scale trials data are presented as a demonstration of ship/model correlation; additional model test results are given to illustrate use of the manoeuvre for detecting changes in stability due to alterations in ship configuration.

Paper 9. Model Testing

1972 ◽  
Vol 14 (7) ◽  
pp. 62-69
Author(s):  
R. K. Burcher
Keyword(s):  
Mathematical Modelling ◽  
Model Test ◽  
Test Methods ◽  
Model Testing ◽  
Short Discussion ◽  
Ship Model ◽  
Constrained Models ◽  
Model Correlation ◽  
Standard Tests

This paper is an introduction to model test methods as a means of establishing the manoeuvring characteristics of ships. Consideration is first given to the reasons for the adoption of model techniques and the information to be obtained. The model techniques are considered under three sections: free models, constrained models and mathematical modelling. The standard tests employed are briefly described and the information that can be obtained, together with any problems. There is finally a short discussion of the problems of ship/model correlation.

CFD Simulation of a Twin-Screw Ship Self-Propulsion Using DDES-Overset Method

2019 ◽  
Author(s):  
Jianhua Wang ◽  
Decheng Wan
Keyword(s):  
Cfd Simulation ◽  
Ship Hull ◽  
The Self ◽  
Detached Eddy Simulation ◽  
Complex Flow ◽  
Ship Model ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Twin Screw ◽  
Cfd Method

Abstract Rotating propellers and moving rudders are necessary for the simulation of free running ship with the purpose of resolving detailed flow interaction. In the present work, CFD method is used to numerically investigate self-propulsion behavior for a twin-screw fully appended ship. The simulation conditions are following the experiment performed at IIHR. The benchmark ship model ONR Tumblehome is used for all the numerical computations. Overset grids are used to fully discretize the ship hull, twin propellers and rudders. Self-propulsion simulation is carried out using a PI controller to achieve target ship speed of Fr = 0.20 in calm water and the ship model is free to trim and sinkage. All the numerical calculations are carried out by the in-house CFD solver naoe-FOAM-SJTU. Unlike most previous studies based on RANS method, the present self-propulsion simulations adopt the Delayed Detached-Eddy-Simulation (DDES) approach to resolve the complex flow around ship hull, propeller and rudder. The main parameters of the self-propulsion as well as flow visualizations are presented. The predicted results are compared with previous RANS data and the available experimental data. The comparison with the experiment is satisfactory and the flow field shows that the present DDES-overset method can give more flow details for the self-propulsion condition.

Direct Simulations of Turning Circle Maneuver in Waves Using RANS-Overset Method

2018 ◽  
Author(s):  
Jianhua Wang ◽  
Decheng Wan
Keyword(s):  
Open Source ◽  
Rotational Speed ◽  
Computational Domain ◽  
Overset Grids ◽  
Ship Model ◽  
Wave Effects ◽  
Twin Screw ◽  
Free Running ◽  
Flow Visualizations ◽  
Onr Tumblehome

In the present work, a RANS-overset method is used to numerically investigate turning circle maneuver in waves for a twin-screw ship. CFD solver naoe-FOAM-SJTU is used for the numerical computations of the fully appended ONR Tumblehome ship model. Overset grids are used to fully discretize the ship hull, twin propellers and rudders. The simulation of turning circle maneuver is carried out at constant propeller rotational speed with 35° rudder deflection. Open source toolbox waves2Foam is utilized to generate desired waves for the moving computational domain. Predicted ship trajectory and 6DoF motions, hydrodynamic forces and moments acting on the ship and the moving components are presented. The main parameters of the turning circle maneuver, such as the advance, the transfer, the tactical diameter, and the turning diameter, are presented and compared with the available experiment. Wave effects on the free running turning circle maneuver are discussed through detailed flow visualizations. The trajectory and main parameters agree well with the experiment, which show that the present RANS-overset method is a reliable approach to directly simulate turning circle maneuver in waves.

Ship-Model Correlation of Powering Performance on USS Oliver Hazard Perry, FFG-7 Class

1983 ◽  
Vol 20 (01) ◽  
pp. 35-52
Author(s):  
Everett L. Woo ◽  
Gabor Karafiath ◽  
Gary Borda
Keyword(s):  
Performance Prediction ◽  
Prediction Method ◽  
Model Tests ◽  
Trial Data ◽  
Full Scale ◽  
Ship Model ◽  
Single Screw ◽  
Post Trial ◽  
Model Correlation

Standardization trials were conducted on USS Oliver Hazard Perry (FFG-7) in May 1978. From the results of the trial data and the post-trial model correlation experiments which simulated the trial conditions, the powering correlation allowance of 0.00045 was obtained for the FFG-7. It should be noted that the pretrial model tests used the design correlation allowance of 0.0005 to predict full-scale powering performance. In addition, the powering performance was predicted using the "1978 ITTC Performance Prediction Method for Single Screw Ships."

scholarly journals Determining the acceptable turning circle manoeuvring modes to avoid loss of efficiency of the twin propeller system

2020 ◽  
Vol 3 (2) ◽  
pp. Manuscript
Author(s):  
Dobrin Efremov
Keyword(s):  
Interaction Effects ◽  
Ship Model ◽  
Oblique Flow ◽  
Twin Screw ◽  
Curvilinear Trajectory ◽  
Thrust And Torque ◽  
Propeller Thrust

Nowadays, a large number of newly built inland and navy vessels are equipped with a twin propeller-twin rudder configuration (TPTR). Observations of the modes of work of each unit of the TPTR system when performing manoeuvres at curvilinear trajectory show asymmetrical loading. The nature and parameters of the phenomenon are not sufficiently studied, which in specific manoeuvres could create overloading and loss of effectiveness. The purpose of the task is to study the effectiveness of the ship’s TP system in manoeuvring, taking into account the specifics of working in oblique flow of the “internal” and “external” propellers, respectively to the trajectory of motion. Appropriate manoeuvring experiments with self-running ship model have been carried out by which the propeller thrust and torque have been measured. In the present paper, based on obtained investigation results, analysis of interaction effects in the TP system has been performed. Coefficients for estimating the asymmetric efficiency of the twin-screw system have been developed, and related conclusions were summarized.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

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