نشریه مهندسی شناورهای تندرو
پیاپی 43 (پاییز و زمستان 1392)

Voith Schneider Propeller (VSP) was invented as a propeller with a high Thrust and control force by Ernst Schneider in 1926. In this propeller, Thrust is provided by changing the steering center. In addition to providing Thrust, VSP can also provide control force. Therefore there is no need to install rudder in vessels with VSP. VSPs are mainly used in Tug boats, coastal ships and those vessels that demand high maneuverability. In the present study, first, changes of arm length and angle of attack for every position of blades are determined using geometry equations. Then, after determining lift and drag forces on blades profile using Oscillating motion, hydrodynamic coefficients are determined.

The application of fast monohulls in the role as patrol, coastguard, survey and naval vessels has increased considerably over the last decades. The improvement of the sea keeping behavior of these fast monohulls has been a research topic for an even considerable longer period of time. The use of fast craft in a seaway has always posed many challenges to the comfort of those on board and the safety of the ship. Partly this is due to the fact that most applications of fast ships are restricted to the relatively smaller vessels. In the past decades, considerable attention has been paid to improving the operability of fast ships in head waves because in those conditions severe damage to people on board as well as to the ship itself could be experienced. The emphasis was on the limitation of the vertical accelerations.For fast patrol boats, the motion behavior in large stern quartering and following seas is often a limiting situation for operability. The broaching tendency that may occur with most of the relatively small (shorter than 50 meters) and fast (more than 25 knots) patrol boats often applied a significant change in forward speed or heading had to be made to prevent serious problems. Use of very sharp bow or AXE Bow Concept is a good solution to overcome problems specially at heading sea.In this concept the stem is vertical, the sheer largely increased, the bottom centerline sloped down towards the bow and the bow sections very, very narrow with almost vertical sides. In the present study emphasis is placed on the restricting phenomena when sailing with fast ships in a seaway and analyzing AXE bow effects.

Unmanned equipment is modern technology that can be used in recently wars in the
fields of air, land and sea. It is combination of modern technology. UnmannedSurface
Vessels are sample of this equipment that used in navy missions regard to intended goals,
environmental condition and existing facilities.In this article we introduce and explain some
of these unmanned vessels with confirm application (usage) of them in the navy. We also
noted the capabilities using and equipment of these vessels in Mission and tactics of the
navy.

In recent decades, the increasing demand for high-speed ocean vehicles in commercial and navy applications has driven the design of more efficient of propulsion systems.As a result, a Rim Driven (Tip Driven) thruster which has become an appropriate alternative in the contemporary design.In This paper, the open water hydrodynamic performance of the four blade hubless Rim driven thruster models at various pitch ratios were investigated by employing the RANS solver andTwo-equation turbulence model k–ε in Ansys-Fluent 14.5. The pressure, velocity and x vorticity distribution in different distances from downstream and various advance coefficients were illustrated and discussed.

In HSC Planning with increasing speed of the vessel, some components considerably increases theirresistance. Decreases in the resistance vessels are usually by the use covered of different strategies,installationequipment and changes in the form of a body is done. One way to reduce the wetted surface resistance vessels Extremist reduce unnecessary floor at high speeds. In this paper, using the CFD software ANSYS-CFX profiles Transom flow separation behind the numerical analysis and experimental results are compared by Savistky 2009. Satisfactory agreement between the numerical and experimental results was observed. Then the pressure distribution charts and one, convenient location, and the first step was to determine the transverse single- step lateral flow around floating body is also analyzed.In all cases, the computational error is less than 8 percent.

Experiments maneuverability capabilities of the necessary conditions for approval of the design are done by standards bodies. Usually ships maneuver in order to simulate mathematical models and experiments and numerical simulations are used. In the study by numerical methods using Computational Fluid Dynamics software, such as Ansys CFX, the hydrodynamic characteristics of a number of single- hull vessels trim angle and a roll angle of Extremist with two different speeds for understanding the hydrodynamic characteristics of vessels in maneuver around the case is investigated. It is noteworthy that since the simulation with the accuracy and extent of any source has been done. Poll Results solved for the accuracy of the results of extensive experiments conducted in the laboratory Davidson is used . Observed that the accuracy of the simulation results well below ten percent at fault and has to be used for industrial purposes is Extremist vessels.

Naval mines, dangerous weapons for military and commercial fleet of floating units which hurt the least cost compared to other naval weapons, are available.Mines are able to stop or slow moving ships. Today, even with modern weapons, naval mines, as one of the most important naval weapons which can be used against surface and subsurface units.The mines in the area to be planted and how to plan a successful operation of mines is an important and effective. This study has tried and covered with the help of a hexagonal honeycomb arrangement providing for innovative ways to offer. The proposed research is designed based on mathematical logic. The software was developed using the simulation method, to calculate the probability of collision of vessels with mines and analyzed the effectiveness of the initiative.