مهندسی دریا
Leila Jozaee; Sahar Damiri; Nassim Ale Ali; Etemadeddin Rabei
Abstract
In this paper, free vibration of the ship with Timoshenko beam model is investigated and natural frequencies and mode shapes are obtained. Since the frequency equations of Timoshenko beam are nonlinear, for obtaining the frequencies and mode shapes, numerical method, differential quadrature method with ...
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In this paper, free vibration of the ship with Timoshenko beam model is investigated and natural frequencies and mode shapes are obtained. Since the frequency equations of Timoshenko beam are nonlinear, for obtaining the frequencies and mode shapes, numerical method, differential quadrature method with discretization is used. Frequencies of some vessels with different geometers such as length, height and width are obtained and versus length, height and width are compared and effect of these parameters on the frequencies are investigated. These investigations show that by increasing these parameters the frequencies are decreased and for the vessels that have a large ratio of height to length, the Timoshenko beam model should be used for vibration investigation that the shear effect is considered.
مهندسی دریا
Moloud Ariyan; Ahmad Hajivand; Etemadodin Rabei Gholami
Abstract
Maneuverability is an important quality of marine vehicles. Hydrodynamic coefficients of ship and rudder should be derived to simulate maneuvering tests. These coefficients can be obtained by using captive model test and empirical formula. Accuracy of rudder hydrodynamic coefficients is important to ...
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Maneuverability is an important quality of marine vehicles. Hydrodynamic coefficients of ship and rudder should be derived to simulate maneuvering tests. These coefficients can be obtained by using captive model test and empirical formula. Accuracy of rudder hydrodynamic coefficients is important to calculate rudder force as the most influence force in ship maneuver, precisely. Empirical formula usually are correspond to single rudder ships and for twin rudder ships numerical or experimental method are used. In this paper, by using numerical method and simulation of static towing test in computational fluid hydrodynamic environment for different angles, linear and nonlinear rudder hydrodynamic coefficients are calculated. Also, fluid velocity field around rudder is obtained to investigate separation for high rudder angle. The comparison of simulated results with the available experimental shows a very good agreement among them.
مهندسی دریا
Saeed Shadkam; EatemadO’Din Rabei Gholami; Nasim Al Ali
Abstract
Each Ship Can Transfer Safely in certain Zone According to It`s Stability and Regime of Sea State. Therefore, if Ship Have to Pass in Specific Condition that Sea State is Jumpy, Should be Provide One or More Anti Rolling Methods to Survive. The Purpose of this Article is Reduction and Control of Rolling ...
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Each Ship Can Transfer Safely in certain Zone According to It`s Stability and Regime of Sea State. Therefore, if Ship Have to Pass in Specific Condition that Sea State is Jumpy, Should be Provide One or More Anti Rolling Methods to Survive. The Purpose of this Article is Reduction and Control of Rolling Motion to Reach Proper Hydrostatic Stability with Assessment Activity of Two Methods Using Commonly to Reduce Rolling Motion. This Methods are Activated Anti Rolling Tanks And Gyroscope. In this Article Trying to Solve Its Equations in Matlab Software and Compare it to Reach More Activity Method. The Results Shown that Anti Rolling Method Proposed for Large Displacement Ships and Otherwise Gyroscope is More Activity for Passenger Ships and Small Vessels.