search query: @keyword verkningsgrad / total: 4
reference: 2 / 4
« previous | next »
Author:Lindfors, Mikael
Title:The effect of propeller geometry in respect to efficiency, pressure pulses and generated noise, at a certain design point
Propellerns geometriska inverkan på effektivitet samt inducerade tryckimpulser och ljud, vid en bestämd design punkt
Publication type:Master's thesis
Publication year:2011
Pages:93      Language:   eng
Department/School:Sovelletun mekaniikan laitos
Main subject:Laivanrakennusoppi   (Kul-24)
Supervisor:Matusiak, Jerzy
Instructor:Korsström, Andrei
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
Instructions

Reading digital theses in the closed network of the Aalto University Harald Herlin Learning Centre

In the closed network of Learning Centre you can read digital and digitized theses not available in the open network.

The Learning Centre contact details and opening hours: https://learningcentre.aalto.fi/en/harald-herlin-learning-centre/

You can read theses on the Learning Centre customer computers, which are available on all floors.

Logging on to the customer computers

  • Aalto University staff members log on to the customer computer using the Aalto username and password.
  • Other customers log on using a shared username and password.

Opening a thesis

  • On the desktop of the customer computers, you will find an icon titled:

    Aalto Thesis Database

  • Click on the icon to search for and open the thesis you are looking for from Aaltodoc database. You can find the thesis file by clicking the link on the OEV or OEVS field.

Reading the thesis

  • You can either print the thesis or read it on the customer computer screen.
  • You cannot save the thesis file on a flash drive or email it.
  • You cannot copy text or images from the file.
  • You cannot edit the file.

Printing the thesis

  • You can print the thesis for your personal study or research use.
  • Aalto University students and staff members may print black-and-white prints on the PrintingPoint devices when using the computer with personal Aalto username and password. Color printing is possible using the printer u90203-psc3, which is located near the customer service. Color printing is subject to a charge to Aalto University students and staff members.
  • Other customers can use the printer u90203-psc3. All printing is subject to a charge to non-University members.
Location:P1 Ark Aalto  3933   | Archive
Keywords:propeller comparison
efficiency
induced pressure pulses
broadband noise
propeller jämförelse
verkningsgrad
inducerade tryckimpulser
bredbandsljud
Abstract (eng): Three propellers, each with different blade number have been designed according to the design point of a cruise ship.
The number of blades varies between four and six.
The propellers have been compared against each other in respect to efficiency, induced pressure pulses and noise generation.
Additionally the effect of skew and rake has been taken into account.

Result shows that the optimal diameter is smaller, the more blades the propeller owns.
The induced pressure pulses are clear1y largest for the four-bladed propeller, but it has also the highest efficiency, if the pitch distribution is similar for each propeller.
The efficiency can be improved by increasing the pitch close to the tip and hub, but this can however cause broadband noise.
The smaller propellers have larger tip clearance, which is beneficial for minimizing pressure pulses.

By introducing skew to the propeller blades, efficiency tends to increase linear1y, and pressure pulses due to loading decreases.
A small rake angle can improve the efficiency slightly and as well cause a reduction in induced pressures.
Forward rake is more beneficial according to improve efficiency, while aft rake reduces the pressure pulses.
Abstract (swe): Tre propellrar av olika blad antal har utvecklats och analyserats på basis av en gemensam design punkt.
Bladantalet varierar från fyra blad till sex blad.
Propellrarna har analyserats i frågan om verkningsgrad, inducerade tryckimpulser, samt oljud.
Dessutom har inverkan på förändring av propellerns skew-samt rake vinkel undersökts.

Resultaten visar att den optimala diametern på propellern minskar da bladantalet ökats.
Mindre propeller medför större avstånd till fartygets skrov, och inducerar därmed mindre tryckimpulser.
Tryck impulserna ar klart högre för den fyra bladiga propellern, men verkningsgraden ar samtidigt bast ifall man tillämpar likadan lyft distribution för alla propellrarna.
Verkningsgraden kan höjas ganska effektivt genom att öka på lyftet nära bladspetsen, men detta medför risk för högre oljud och eventuellt kavitation.

Med att införa en skew på propellern ökar verkningsgraden effektivt, samtidigt som de inducerade tryckimpulserna minskar.
Även en minimal rake vinkel ökar något på verkningsgraden, då den är framåtriktad.
En bakåtriktad rake vinkel minskar däremot effektivare på tryckimpulserna, samtidigt som verkningsgraden förblir konstant.
För större vinklar än 5° börjar verkningsgraden kraftigt sjunka.
ED:2012-01-25
INSSI record number: 43852
+ add basket
« previous | next »
INSSI