OP WEG NAAR EEN BETER
SCHROEFONTWERP
Tom van Terwisga, Evert Jan Foeth, Auke v.d. Ploeg,
Gert Jan Zondervan, Guilherme Vaz e.a.
CONTENTS
•
•
•
•
The origin of propellers
Propeller design in the past
Contemporary propeller design
Propeller design in the future
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Milestones in the history of
ship propellers
3
~ 1830 - WHO INVENTED THE SHIP’S PROPELLER
James Watt, in 1770, wrote: "Have you ever
considered a spiral oar?"
Joseph Bramah, in 1785, patented the idea of a
"screw propeller", but never tried it in practice.
The Austrians have statues to Joseph Ressel, whom
they claim as the inventor (see below).
Various people took out patents in England and
America from 1794 onwards, though nothing
practical was achieved.
Richard Trevethick, in a 1815 patent, describes the
screw propeller with considerable minuteness.
John Swan was heralded the practical inventor, after
a trial boat driven by a spring, in 1824.
And so on. . .
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Gravestone of James
Steadman (1790-1865)
~1890 - FIRST AWARENESS OF CAVITATION
Turbinia initially reached a disappointing
speed of approx. 20 kts at 18000 rpm for
main shaft
Prop. rpm was reduced to some 2000 rpm
and a total of 9 propellers was mounted
(three propellers on three shafts). Speed
record was set at 34.5 kts.
Parsons analysed the problem with thrust
breakdown due to vapourous cavitation
and was first to use this term in its current
meaning (word originally introduced by
W.Froude)
DEVELOPMENT OF CAVITATION PROBLEMS
• approx. 1890 – Thrust breakdown on
Turbinia
• 1950’s - vibrations, erosion, thrust
breakdown, noise
• 1960’s serious vibration problems on
large & full tankers
• 1990’s:
–
Increase in power density and ship
speed (ferries, cruise vessels,
container ships, dredging vessels)
• 2008 – now
–
–
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Decrease in speed, increase in
demand for low fuel consumption
Need for balancing efficiency cavitation
EFFICIENCY LOSS DUE TO CAVITATION
“Adaptations of the propeller geometry needed for cavitation
control reduce the propeller efficiency.
It is difficult to quantify how much the efficiency is reduced in
general. It can be checked case by case by calculating first the
optimum efficiency without cavitation constraints and then the
actually achieved efficiency.
A rough estimate could be that losses are in the
range of 5 to 10%.”
From Ligtelijn (2010): “The pay-off between cavitation and
efficiency”, IMAREST seminar on marine propulsion
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EXAMPLE OF CAVITATION EROSION BY PRE-SWIRL STATOR
Van Terwisga et al. (CAV 2009) –
Courtesy Lloyds Register
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Propeller design…
…in the past
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WAGENINGEN B-SERIES PROPELLERS
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PHD STUDIES ON PROPELLERS FROM DELFT UNIVERSITY
• Van Lammeren [1938] – Analyse der Voortstuwingscomponenten in verband
met het schaaleffect bij scheepsmodelproeven
• Van Manen [1951] – Invloed van de ongelijkmatigheid van het snelheidsveld
op het ontwerp van scheepsschroeven
• Oosterveld [1970] – Wake adapted ducted propellers
• Van Oossanen [1974] – Calculation of performance and cavitation
characteristics of propellers including effects of non-uniform flow and viscosity
• Van Gent [1977] – On the use of lifting surface theory for moderately and
heavily loaded ship propellers
• Kuiper [1981] – Cavitation inception on ship propeller models
• Vaz [2005] – Modelling of Sheet Cavitation on Hydrofoils and Marine Propellers
using Boundary Element Methods
• Van Wijngaarden [2011] – Prediction of propeller-induced hull-pressure
fluctuations
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Propeller design…
…& Tool development…
…today
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CURRENT PROPELLER DESIGN PROCESS
• PHASE 1 – Parameter selection
•
Determination design constraints and main propeller characteristics
• PHASE 2 – Detailed geometry
•
Determination detailed propeller geometry for specific application (wake
adapted)
• PHASE 3 – Detailed evaluation
•
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Detailed flow analysis (Experiments and/or CFD), evaluation of
performance and design modifications to improve balance between
performance and cavitation hindrance (vibrations, erosion)
PROPELLER DESIGN TODAY – PHASE 2 IN DETAIL
• Wakefield representation: Circumferentially averaged effective
wake
• Max. efficiency objective leads to preferred pitch distribution
• Cavitation constraints lead to sectional shape and radial camber
distribution
• Adjust selected parameter distributions to meet additional
constraints (e.g. strength and for CPP blade spindle torque and
blade passage)
Result: Detailed 3D propeller geometry (complete surface or
volume geometry)
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… but how is this process
improved?
…and how much can we
expect?
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Efficiency gains in the order
of 10 to 15% are possible
Ligtelijn (2010)
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TOOL DEVELOPMENT – EU PROJECT DEVELOPMENT
•
•
•
•
•
•
Fantastic – FP5 – optimization of ship resistance
EROCAV – Prediction of cavitation erosion
LEADING EDGE – FP6 – prediction of vortices from propeller
VIRTUE – FP6 – development of CFD tools
STREAMLINE – FP7 – Improvement of propulsors
GRIP – FP7 – Energy saving by ESD
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RENEWED PROPELLER DESIGN PROCEDURE
• Propeller geometry description
•
From a coarse approx. 6 par description to a fully defined 60 par
description
•
Statistical analysis of these parameters on propeller database containing
1250 propeller designs
Example of probability density
function for Blade Area Ratio
Fixed Pitch and Controlable Pitch
Propellers together!
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RENEWED PROPELLER DESIGN PROCEDURE
• Propeller design generation
•
Fast generation and analysis of approx. 10,000 propeller designs per day
• Control of statistical
parameter limits
• Automated meshing for
panel code PROCAL
analysis
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PROPELLER GEOMETRY – GREATER FREEDOM
Great flexibility in propeller generation might lead to unfeasible or
propellers with convergence problems
Extreme tip skew – poor
convergence
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Minute chord length at
hub – poor convergence
Very small pitch at hub –
poor convergence
ADEQUACY OF PANEL CODE COMPUTATIONS
1.0
0.9
0.8
0.7
0.6
KT, 10KQ, hO
0.5
0.4
0.3
0.2
0.1
0.0
0.0
21
0.1
0.2
0.3
0.4
0.5 0.6 0.7 0.8
Advance Coefficient [-]
0.9
1.0
1.1
1.2
1.3
Efficiency
EFFICIENCY VERSUS THRUST VARIATION
1st blade rate harmonic of thrust variation
Propeller efficiency as a function of thrust variation with
parent propeller as reference
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propeller – hull integration …
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COMPARISON OF CANDIDATE HULL FORM 1 WITH ORIGINAL
Candidate hull form in black
Original in red
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TRADE OFF BETWEEN EFFICIENCY AND WAKE QUALITY
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Full unsteady RANS analysis of
propeller-hull system…
… REFRESCO results
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PROPELLER ANALYSIS WITH REFRESCO
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SHIP-PROPELLER ANALYSIS WITH REFRESCO
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Propeller design…
…in the future
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DESIGN OF PROPELLERS – LIMITS?
from 65 to 90 %
efficiency?
where are the
limits?
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RELATIVE ENERGY LOSS TERMS FOR OPEN PROPELLERS
Efficiency
axial losses
rotational losses
viscous losses
Thrust loading
Choi [2009]
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32
ENERGY BALANCE CONSIDERATIONS
PD 

AWP
1
2
2
2
  uxWP
 U 02   urWP
 u2WP  uxWP rdrd    p  p0  uxWP rdrd  dissP
AWP
WP
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R&D FOCUS
• Challenges:
•
•
•
Develop toolkit and procedures for integrated hull-propulsor design,
including ESDs
Explore design space spanned by conflicting requirements (efficiency –
cavitation nuisance)
Include service conditions in design process
• Response:
•
Development of toolkit
•
•
Explore design space spanned by conflicting req’s.
•
•
•
Study of optimization techniques
Design studies by propeller design group
Effect of service conditions
•
•
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PROCAL, FRESCO, PARNASSOS and erosion assessment
CRN (Coop. Research Navies)
Phd Studies: P. Schulten en A. Vrijdag
THANK YOU …
… for your attention.
We would be most grateful if you could give your
comments on our development strategy.
As only together can we keep our Leading Edge in
the world market place!!!
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