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Pivoted or fixed fins in an azimuthing propulsion unit

IP.com Disclosure Number: IPCOM000249054D
Publication Date: 2017-Jan-31
Document File: 6 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Related People

Pellinen Petri: AUTHOR

Abstract

Pivoted or fixed fins to be used in a propulsion unit are suggested. The fins may be pivoted i.e. the angle of incidence of the fins may change according to the speed of the vessel. Pivoted fins provide a better efficiency and it is possible to optimize their use in a larger speed interval compared to fixed fins. The fins may be mounted on the sides of the frame of an azimuthing propulsion unit i.e. on a place where there is plenty of room. Also the empty space within the frame of an azimuthing propulsion unit may be used for the equipment needed to support the fins.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 37% of the total text.

Page 1 of 6  FI-1609801

© Copyright [2017] ABB. All rights reserved.

PIVOTED OR FIXED FINS IN AN AZIMUTHING PROPULSION UNIT

The hydrodynamic efficiency of an azimuthing propulsion unit may be improved by

utilizing the energy in the water turbulence caused by the propeller. One prior known

method to achieve this is to use fins on the outer surface of the pod, said fins turning a

portion of the energy of the water turbulence of the propeller into thrust, whereby the

efficiency is improved. An example of an azimuthing propulsion unit is Azipod®

(registered trademark of ABB) manufactured by ABB.

Such fins are used in several different applications in vessels. An azimuthing propulsion

unit may be provided with fins positioned immediately behind the propeller. Fins may

also be used in vessels provided with one or more shaft lines, whereby the fins may be

mounted behind and before the propeller.

The fins that are used in prior art solutions are static i.e. they are fixedly attached. This

means that their angle of incidence is fixed and optimized for a certain speed i.e. the

fins are tilted with a fixed angle in relation to the horizontal plane. This means that when

the speed of the vessel is lower or greater than the optimum speed, the fixed fins will

cause drag i.e. they will not function optimally. The fins will thus cause additional

hydrodynamic resistance to the vessel in these situations.

The mechanical durability and the manufacturability of the fins have also been a

technical challenge in prior art solutions.

The inventive fins may include e.g. the following features:

The fins may be pivoted i.e. the angle of incidence of the fins may change according to

the speed of the vessel. Pivoted fins provide a better efficiency and it is possible to

optimize their use in a larger speed interval compared to fixed fins.

The fins may be mounted on the sides of the frame of an azimuthing propulsion unit i.e.

on a place where there is plenty of room. Also the empty space within the frame of an

azimuthing propulsion unit may be used for the equipment needed to support the fins.

Page 2 of 6  FI-1609801

© Copyright [2017] ABB. All rights reserved.

The efficiency of an azimuthing propulsion unit may be improved by approximately 6-7%

compared to a prior art azimuthing propulsion unit. Fuel costs will thus be reduced.

It is possible to achieve a greater thrust with a pressure bearing of the same size due to

the fact that the pressure bearing does not see the additional thrust as the additional

thrust is provided by the fins and is supplied by the frame of the azimuthing propulsion

unit.

The figures show technical solutions using pivoted fins in an azimuthing propulsion unit.

These solutions are simple and robust. The empty space in the frame of an azimuthing

propulsion unit is used for the pivoted fins.

Figure 1 illustrates the inventive solution. There are horizontal fins positioned on each

side of the frame hat of an azimuthing propulsion unit. The fins...