جستجوی مقالات مرتبط با کلیدواژه "pitch" در نشریات گروه "مهندسی دریا"

This article presents a new innovative method to reduce the motions and stabilizing the ships using the ordinary fishing net. The study of ship motions in the waves has been the main concerns of ship designers. Some methods have been used to stabilize the ship in the waves, such as stabilizing tanks, gyro stabilizers and fin stabilizer, which these have their own advantages and disadvantages. In this paper, the study of the net element to reduce the amplitude of Pitch motion in the regular waves in the static state has been done by experiments in a towing tank. The model experiments were performed in the towing tank of National Iranian Marine Laboratory (NIMALA) using two kinds of net with different meshes to compare the effects. The innovative idea of using the fishing net element to reduce the ship motions in the waves was presented for the first time in this research. The findings of this study for the planing craft show a reduction in Pitch motion of up to 20% in regular waves. The length of the model is 2.5 meters and the requirements of the test method are based on the ITTC marine testing instructions.

In this paper, the dynamic responses of the KVLCC2 tanker at differents speeds have been evaluated using a numerical method. Ship movements and the forces acting on it have been determined accurately based on computational fluid dynamics method using OpenFoam open source code. Free surface of the two phase flow has been simulated using interFoam and interDyMFoam solvers. The amplitude of ship's heave and pitch motions have been determined in the regular head waves at various speeds. The regular second order stokes wave is generated using the input speed technique. In order to verify the accuracy of the numerical results obtained from the present study, the values of the heave motion, rolling angle, thrust coefficient, as well as added resistance compared with the validated experimental results presented by other researchers. In addition, free surface contours and important flow parameters have been extracted. Also, heave and pitch RAO changes are presented and compared with valid experimental results. These simulations are carried out at different speeds and current numerical results have acceptable accuracy compared with experimental data. By comparing the average force applied to the hull in the waves with the amount of calm water resistance, the amount of added resistance is determined at different speeds. The ratio of the added resistance to the total resistance decreases with increasing the Froude number. Due to the hull form of the tanker, the calm water resistance has a higher growth rate relative to added resistance. Such an analysis, using virtual wave making techniques and simulating dynamic behavior Conforms to reality, can provide more accurate results than potential methods and can be used in a wider range of marine applications.