fuel efficient tanker design karsten hochkirch...fuel efficient tanker design 19 ship efficiency...
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Fuel efficient tanker design
Karsten Hochkirch
DNV GL SE
Germany
27-9-2017
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DNV GL © 2017 SAFER, SMARTER, GREENER DNV GL © 2013
Fuel Efficient Tanker Design
Ship Efficiency Conference, Dr. Karsten Hochkirch, DNV GL
Hamburg, 2017-09-26
MARITIME
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1,000+ vessels optimized:
*) assuming an average fuel price of 300 $/ton
ECO Lines
ECO Retrofit
ECO Assistant
Savings per day overall
CO2 [t] 7,900 7.7 Mio
Fuel [t] 2,600 2.5 Mio
Costs* [$] 0.52 Mio 750 Mio
Fuel Efficient Tanker Design
Yesterdays ideas – tomorrow’s savings
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Maritime Advisory in DNV GL
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Fuel Efficient Tanker Design
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Shipping Advisory Concept Advisory Structures Noise & vibration
Hydrodynamics
Mechanical & Systems Eng.
Safety, Risk & Reliability
Lifecycle Management
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DNV GL © 2017
Agenda
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1. Today’s design tools
2. Yesterday’s ideas
3. Tomorrow’s savings
DNV GL © 2017
Agenda
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1. Today’s design tools
2. Yesterday’s ideas
3. Tomorrow’s savings
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DNV GL © 2017
Hull lines development – traditional way
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Open drawer
Select similar ship
Adjust dimensions
Some selected CFD
Modeltesting
Bossing
Rudder configuration
Propeller position
Done!
Variations looked at < 10
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Optimization Optimization
Today’s design tools – DNV GL’s unique optimization process
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Geometric
modeling
Postprocessing Postprocessing
Detailed CFD
Optimization
Algorithm
Performance
assessment
Hydrostatic analysis
constraint check
Virtual towing
tank test
Preprocessing Preprocessing
Setup objectives
and constraints Parametric model
traditional
tank test
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DNV GL © 2017
Optimization of a LEG carrier – multi-objective optimization
Case AC (Scantling) weighted by 25%
– Draft : 9.50 m
– Speed: 14.3 kn
Case BB (Design) weighted by 50%
– Draft: 7.50 m
– Speed: 15.3 kn
Case CA (Ballast) weighted by 25%
– Draft aft: 6.50 m
– Draft fwd: 4.50 m
– Speed: 15.8 kn
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LEG Tanker – Baseline & Optimized
2012/08/08 10
Optim
ized B
aseline
Case AC (scantling draft) – Dynamic pressure distribution
model scale = 25
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DNV GL © 2017
LEG Tanker – Baseline & Optimized
2012/08/08 11
Case BB (design draft) – Dynamic pressure distribution
model scale = 25
Optim
ized B
aseline
DNV GL © 2017
LEG Tanker – Baseline & Optimized
2012/08/08 12
Case CA (light draft) – Dynamic pressure distribution
model scale = 25
Optim
ized B
aseline
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DNV GL © 2017
LEG Tanker – Results
2012/08/08 13
Case Relative total resistance Optimized/ Baseline
Achieved Improve
ment
Weight
AC (scantling) 84.0% 16.0% 25%
BB (design) 82.9% 17.1% 50%
CA (ballast) 95.3% 4.7% 25%
Weighted total improvement in RT [%]
13.7%
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Benefit of hull lines optimizations for various ship types
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0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
22%
24%
26%
0 50.000 100.000 150.000 200.000 250.000
Improvement level
Displacement [t]
Achieved improvement
for the specific operating
profile relative to the
baseline design
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Motivation
Fuel Efficient Tanker Design
19 Ship Efficiency Conference, Hamburg 2017-09-26
Ship type RoPax Ferry 14000 TEU ULCV Gas Tanker 76k Bulker
Lpp / B / T m 200 / 27 / 13.0 397 / 56.4 / 16.5 145/21.6/9.5 225x32.2x14.5
Speed kn 25 26 16.5 14.5
Displacement t 80,000 240,000 76,000
Installed power kW 37,000 54,000 6,000 8,500
Service condition (75%) kW 27,750 40,500 4,500 6,375
Time at sea days/year 200 250 250 220
h/year 4800 6000 6000 5280
Engine Fuel type IFO380 IFO380 IFO380 IFO380
Fuel oil price $/t 325 325 325 325
Specific fuel consumption kg/kWh 0.175 0.175 0.175 0.175
Sludge % 1.5% 1.5% 1.5% 1.5%
Savings
Assumed improvement % 5.0% 4.0% 11.0% 5.0%
Fuel oil savings t/day 5.9 6.9 2.1 1.4
Fuel savings t/year 1183.0 1726.5 527.5 298.9
Reduced investment in main engine $ 301,327 351,820 107,501 69,224
Annual savings per vessel $/year 384,469 561,117 171,453 97,156
Annual savings for a fleet of 5 1,922,347 2,805,587 857,263 485,782
Emmisions saved per year (approx.)
Carbon dioxide (CO2) t/year 3,903.8 5,697.5 1,740.9 986.5
SO2 t/year 94.64 138.12 42.20 23.92
NOx t/year 99.90 145.80 44.55 25.25
DNV GL © 2017
Agenda
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1. Today’s design tools
2. Yesterday’s ideas
3. Tomorrow’s savings
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DNV GL © 2017
Since engineers have understood the nature of “rotative” propulsion it is
known that a part of the energy is left behind as rotation in the flow field.
pre-rotation or pre-swirl in front of or equalization behind the propeller saves
propulsive energy.
Several measures and devices were introduced to produce pre-swirl or reuse
the rotating flow behind the propeller.
Most of the ideas that are practically used are based on ducts or fins.
Rotational losses
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Fuel Efficient Tanker Design
DNV GL © 2017
Yesterday’s ideas…
Nönnecke pioneering in the 60’s
Asymmetrical aft ship
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Symmetry vs. Asymmetry
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Fuel Efficient Tanker Design
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Asymmetric stern
Pros
Introduces pre swirl (similar to fins)
Improves propulsive efficiency
No appended devices, better structural
integrity
Cons
More complex to build
Optimization and analysis is more
complex
Model tests or advanced CFD methods
are required
Traditional design is unlikely to yield
optimum
Likely increase in Resistance
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Optimization – PD / PE
24 February 2017 29
PD [-]
PE [-]
Asymmetric Aft Ship Optimization for a 38,000 dwt Tanker
Trade-off between Effective
and Delivered Power
DNV GL © 2017
Agenda
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1. Today’s design tools
2. Yesterday’s ideas
3. Tomorrow’s savings
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DNV GL © 2017
New design tools
Combining
state of the art Propeller computation tool
Viscous RANS analysis
Gives a perfect team to deliver best accuracy + good response time
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DNV GL © 2017
Optimization Optimization
Today’s design tools – DNV GL’s unique optimization process
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Geometric
modeling
Postprocessing Postprocessing
Detailed CFD Optimization
Algorithm
Performance
assessment
Hydrostatic analysis
constraint check
Virtual towing
tank test
Preprocessing Preprocessing
Setup objectives
and constraints Parametric model
traditional
tank test
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BEM/RANS
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DNV GL © 2017
In a recent project, a 3000 TEU container carrier was tuned to achieve minimum power
consumption. Starting from a well optimized symmetric baseline design the additional
freedom for an asymmetric aft ship design achieved a propulsion power reduction of
3% as confirmed by the model test.
3% decrease of power found for a container feeder vessel
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Fuel Efficient Tanker Design
- 3% in model tests
DNV GL © 2017
3.8 % decrease of power found for a tanker vessel
Allowing asymmetric stern shapes in the
optimization for a well designed 38k dwt tanker
yielded an some 3.4% and 3.8% improvement on
performance in ballast and design condition,
respectively.
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Conclusion
Combining advanced CFD technology with formal parametric optimization the
great idea of the asymmetric aft body can be driven to its maximum potential.
The asymmetric stern allows further improvement of propulsive efficiency
exploiting similar effects as pre-swirl devices, albeit with much higher structural
robustness.
Predicted improvements were confirmed in model tests.
Gains are expected to be higher for Tankers and Bulkers than for Containerships.
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DNV GL © 2017
SAFER, SMARTER, GREENER
www.dnvgl.com
Thank you.
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Dr. Karsten Hochkirch
+49 171 4040017