Claim Missing Document
Check
Articles

Found 6 Documents
Search

A New Implementation of Vortex Lattice Method Applied to the Hydrodynamic Performance of the Propeller-Rudder Ghassemi, Hassan; Allafchi, Farzam
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 16 No 1 (2015): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v16i1.458

Abstract

This paper describes a new implementation of a vortex lattice method based on modified lifting line (VLML) for ship propeller-rudder. Method has been employed to estimate hydrodynamic performance and flow fields, for design and analysis. For this purpose, the results obtained using theoretical model are validated against experimental data, carried by Tamashima et al. [18], concerning to propulsor system. Comparison of these results indicates good agreement with those of the experimental data. Therefore the method can be used as a fast tool for preliminary design and analysis.
Calculations of the Heave and Pitch RAO’s for Three Different Ship’s Hull Forms Ghassemi, Hassan; Majdfar, Sohrab; Gill, Valiollah
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 22 No 1 (2015): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v22i1.441

Abstract

The research carried out in this article is to determine the RAO (Response Amplitude Operator) heave and pitch motions of three different ship’s hulls forms. Ship is running at the head sea of the regular wave and its responses are obtained by modified strip theory using Maxsurf software. Three different ship’s hull forms (Wigley-S60-DDG) are selected in order to predict the results. The obtained results of RAO heave and pitch motions are presented and discussed at various Froude numbers.
Hydrodynamic Effects of the Length and Angle of the Ducted Propeller Majdfar, Sohrab; Ghassemi, Hassan; Forouzan, Hamid
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 25 No 1 (2015): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v25i1.434

Abstract

Ducted propellers used in many vessels, especially fishing vessels, trawlers and submarine which provide the higher efficiency. In this article, the effects of the duct length and duct angle are investigated on the hydrodynamic performance. First, did the modeling of duct 19A. The Kaplan propeller performance with nozzle 19A by turbulence model of SST-K-w analyzed and validated with experimental results that indicate acceptable accuracy. Finally, by changing the nozzle at a rate of 10% and 20% of the original length of the nozzle and also change the angle of the nozzle, analyzed the effects of the changes made. The Kaplan propeller with 19A nozzle is selected for case study. A Reynolds Average Navier-Stokes (RANS) turbulence model of the SST-K- w employed for the present calculations. Numerical results are included pressure distribution, hydrodynamic characteristics and velocity behind the propeller at various geometry and physical conditions. Comparisons of the results are shown with acceptable agreement by the experimental data. It is concluded that the position of the propeller and increasing the duct angle inside the duct may be limited.
Determination of the Lift and Drag of 2D Planing Flat Plate Riding on the Free Surface Rezaei, Amin; Ghassemi, Hassan; Noshadi, Esmail
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 26 No 1 (2015): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v26i1.430

Abstract

The behavior of planing hull is very similar to planing flat plate. So to treat the planing hull performance at moderate Froude number, 2D planing flat plate was analyzed in different Froude number between 0.5 and 1. Finite volume, using ANSYS-CFX v14 software with RNG turbulence model was used to simulate planing plate. The numerical results of the pressure distribution, free surface profile, lift and drag at different AOAsare presented and discussed.Present calculations are compared with Kramer et al [7] results and show almost good agreement.
Hydrodynamic Modeling of Water-Entry of the Wedge Shape with Considering Asymmetric Impact Ghassemi, Hassan; Rayatpisheh, Ali; Ta’abbodi, Navid
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 29 No 1 (2016): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v29i1.417

Abstract

The slamming of the planing crafts is the most important structural phenomenon that a vessel is encountered during their career. Many researchers have investigated this phenomenon in various methods. In this paper we investigated the analytical results of impact of symmetrical wedge to the water surface briefly, then the asymmetric impact of a 2D section of a wedge to the water surface was studied. To analyze above phenomenon, we used a numbers of analytical relationships that summarizes how to achieve these equations. Finally, obtained analytical relationships were used to determine the pressure distribution and maximum value on a wedge with different deadrise angles. The results indicated good agreement between the obtained results and results of other researcher’s studies.
Helmholtz Equation Applied to the Vertical Fixed Cylinder in Wave Using Boundary Element Method Ghassemi, Hassan; Gharechahi, Ataollah; Soleimani, Kaveh; Ketabdari, Mohammad Javad
Journal of Ocean, Mechanical and Aerospace -science and engineering- Vol 36 No 1 (2016): Journal of Ocean, Mechanical and Aerospace -science and engineering- (JOMAse)
Publisher : International Society of Ocean, Mechanical and Aerospace -scientists and engineers- (ISOMAse)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36842/jomase.v36i1.401

Abstract

Helmholtz equation is employed to the wide variety of engineering problems. This paper presents using Helmholtz equation to the vertical fixed cylinder against regular wave by the boundary element method (BEM). The results are included the pressure and forces on the cylinder. The present results are compared with available data, and show in good agreement. The results show that up to a certain dimensionless wave length, the wave force has a direct relation with the dimensionless wavelength, while after the force decreases with the increase of the dimensionless wave length.