Open water tests of twin-propeller podded propulsion system

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School of Engineering | Master's thesis
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Date

2010

Department

Sovelletun mekaniikan laitos

Major/Subject

Laivanrakennusoppi

Mcode

Kul-24

Degree programme

Language

en

Pages

60 s. + liitt. 14

Series

Abstract

The purpose of this work is to study the influence of propeller characteristics with twin-propeller propulsion system to increase the propulsive efficiency. The propulsive efficiency can be presented as the product of three efficiencies: propeller efficiency, hull efficiency and relative rotative efficiency. The propeller characteristics are expressed by the propeller efficiency, therefore one solution to increase propulsive efficiency is to increase the propeller efficiency. The idea of this thesis is to test the propeller-to-propeller interaction in open water condition with different setup cases characterized by different distances between the propellers. Open water tests are conducted with 4 different setup plates and distances between the propellers, the rotational direction of propellers for each setup plate were inward and outward respectively, thus the total amount of test cases were 8. The shortest distance between the tips of propeller blades was 4.5mm and largest 40rnm. Two setup plates were arranged with straight positioned pods while the propellers were positioned side by side in the same plane and two setup plates were with 3° toe angle while the pods were turned inward. An overlapping arrangement is not considered in this thesis. The upstream flow is assumed to be ideal and equal with advance velocity. The thrust deduction of the pods is assumed to be constant and it is not considered either. Propellers are assumed to rotate in homogeneous flow and the wake generated by the pods is not considered. The test results indicate that there was only a minor difference of propeller characteristic values while changing the distances between the propellers.

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Supervisor

Matusiak, Jerzy

Thesis advisor

Hanhirova, Keijo
Naar, Hendrik

Keywords

twin-propeller, propeller-to-propeller interaction, open water tests

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-2020122357889

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[dipl] Insinööritieteiden korkeakoulu / ENG