Posted on the under Marine Engineering , Views 1240 , Add a comment

 

Marine Nozzle How Works

.

To obtain the most thrust, a propeller must move as much water as possible in a given time. A nozzle will assist the propeller in doing this, especially when a high thrust is needed at a low ship speed. As we already know, as the propeller blades rotate in the water, they generate high-pressure areas behind the each blade and low pressure areas in front, and it is this pressure differential that provides the force to drive the vessel. However, losses occur at the tip of each blade as water escapes from the high pressure side of the blade to the low pressure side, resulting in little benefit in terms of pushing the vessel forward. The presence of a close fitting duct around the propeller reduces these loses by restricting water flow to the propeller tips.

.
rice 64 Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

.

The cross sectional area at the entrance of the nozzle is greater than at the trailing throat. Since the water density is constant, the water must accelerate from one to the other. Hence the water is already moving faster as it reaches the propeller than it would on a conventional open propeller. Therefore, more water is moved and more thrust created for the same input power and torque.

However, there are efficiency gains to be made even when it comes to the nozzle design. Some designs will drag as the speed of the advance increases. With the Kort nozzle design, this drag becomes more significant at higher speeds and can eventually reduce the overall thrust gain to zero. The coefficient of drag is over 17 times less with the Rice speed nozzle than the Kort 19A design.

.
ricespeednozzleprofile Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

 

Rice Speed Nozzle Profile

ricethrustnozzleprofile Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

Rice Thrust Nozzle Profile

.
The section of a Rice-Speed Nozzle was developed from air wing sections displaying highest lift/lowest drag properties. When nozzle sections of Kort 19-A and Rice-Speed are compared in Figure 2 below, the drag coefficient of a Rice-Speed Nozzle is 17 times lower than Kort 19-A type.

 

nozzle diagram iso Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

 

 

 

 

 

 

 

Comparison of Drag Coefficient Between Kort and Rice Nozzles 

 

kortdrag Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle
.
Kort Nozzle 19a cd = 0.17
.
ricedrag Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle
.
Rice Nozzle cd = 0.01
.

OPERATIONAL ANALYSIS OF A RICE SPEED NOZZLE

..

Due to the design (Figure A), the propeller’s working area in the centre of nozzle, is approximately 40% smaller than the area of the nozzle entrance. This results in an increase of water speed and a decrease of internal pressure in relation with external pressure – which remains more or less constant.

Because of this pressure difference, a force P (Figure 4) is created on the external surface of the nozzle that is always perpendicular to this surface.
Due to the design of the outside trailing end part of the nozzle, the horizontal component of this force P creates an additional forward thrust on the nozzle; increasing the total thrust of the vessel.

figure3 Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle
Figure A Transverse View of Rice Nozzle.

 

figure4b Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle                 figure4a Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

Figure B Pressure Differences Creates Additional Forward Thrust.

 

Propeller Nozzles

 

108jizi0v Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

.

Sip Marine Custom Nozzles

 

Sip Marine has designed three new nozzle types with the most modern CFD techniques. From these three basic types may Sip Marine connecting to optimize the hull to give the highest possible efficiency.

Sip High speed nozzle


This nozzle is designed for cargo from which the speed is around ten knots. The profile of these nozzles is slim so that it has little resistance. The suspension of these nozzles is applied by outriggers to the ship’s hull to prevent too much resistance of a head box.

Sip High Thrust Nozzle


The high thrust nozzle is characterized by maximum thrust forward and astern. Application at low speed vessels as tugs and workboats.

Sip High Catch Nozzle


The high catch nozzle has been specially developed for beam trawling. This nozzle gets its optimum thrust at fishing speeds of about 5 to 6 knots.

Sip Pre-Swirl Stator Nozzle


By applying the stators in front of the propeller thrust can be increased even further. The stators are a kind of stationary propeller that in combination with the propulsion propeller works as a counter-rotating screw. Depending on the load, an efficiency gain of 3-5% can be achieved.

………………………………………………………………..

Download this catalog

 Marine (Ship) Nozzle ,Type,Sip Marine Custom Nozzles and How Works Nozzle

……………….

Marine (Ship) Nozzle.PDF

Leave your opinion

A total of 0 users commented