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©2008 DK GROUP NETHERLANDS BV ALL RIGHTS RESERVED1

DK Group

A new age of innovation:

Efficiency optimization's vital role in an era

of economic downturn and high fuel pricesby Johannes Johannesson, Naval Architect


DK Group Marine Innovators at a glance

• Established in 2000, DK Group develops and

markets fuel saving technologies to the global

shipping industry

• DK Group has developed a unique and patented

technology for the commercial shipping industry,

the Air Cavity System (ACS)

• Numerous tank tests support bunker

consumption reduction of 5% to 15% from

applying the ACS technology on different vessel

types

• Tests are carried out together with leading market

participants and potential customers

• Savings translate directly into financial benefits

as well as a cleaner environment from reduced

CO2 emission and other greenhouse gasses

Introducing DK Group


Compressor

Air Cavity

ACS technology overview

What is the Air Cavity System ?


Standard vessels types

Tanker vessels Containerships

Gas vessels

VLCC

VLBC

10,000 TEU+

LNG

Suezmax

Aframax

Panamax

Handymax

Panamax

HandymaxCapesize

LPG

8,000 TEU

7,000 TEU

5,500 TEU

3,500 TEU

1,700 TEUUSD 120m

USD 95m USD 215m

USD 150m+

USD 60m+ USD 110m+

USD 60m USD 90m+

USD 30m+

USD 45m+ USD 40m+

Bulk carriers

Standard vessel types


2,700 DWT, 83 m LOA

ACS Demonstrator

ACS Demonstrator the first vessel with ACS

ACS trials

• Build in 1975 at Sietas

Schiffswerft in Germany,

B.No. 697

• Dry Cargo

• Converted in 2008 with

ACS at Gryfia Repairyard in

Poland

• Mini Bulker

• 2800 DWT

• Length 81.0m

• Breadth 13.40 m

• Draft 5.80 m

• Speed 12 knots


ACS trials

ACS Demonstrator full scale trials

Purpose:

• Demonstration of the

concept

• Confidence of scaling

method for the model

tests

• Making test at a high

Reinoldsnumber.

• Real life test of the

Automation system for

the cavities.

• ACS Demonstrator is a

model for VLCC.


ACS Demonstrator sea trial in Oslofjord

• Sea trials conducted with and without ACS

• FORCE and Germanischer Lloyd performed sea trials in

accordance with standard procedures

• ACS demonstrator tests included:

– Speed trials in calm water

– Speed tests in waves

– Maneuvering tests

• Environmental conditions of waves and ocean current

documented by wave buoy.

• Based on the sea trial results with ACS, the scaling

procedure for ACS will be established and more

reliable results for large ocean-going ships can be

conducted.

ACS trials


0

1

2

3

4

5

6

1.E+06 1.E+07 1.E+08 1.E+09 1.E+10

Re

Cf

(*1

,00

0)

8 m model

Full scale

83 m coaster

Reinoldsnumber and Scaling

• Model tests made with 8m

model in Scale 1:10 as ACS

Demonstrator

• Model test using 8m model

of ACS Demonstrator as

model for VLCC Scale 1:40

• Model test using ACS

Demonstrator as model for

VLCC scale 1:4

• Full scale tests as ACS

Demonstrator

ACS trials


ACS Demonstrator sea trial in Oslofjord

ACS trials


ACS trials

Automation of the Air Cavity System

• The ACS system is a part of

the vessel and should not

increase the complexity in the

vessels operation

• Development of suitable

sensors

• Development of automation

strategy

• Reliability of the automation

system.


ACS trials

Automation of the Air Cavity System

• The vessel is rolling approx -8

deg to 8 deg.

• The sensors are able to

measure the water level

inside the cavity.

• The system reacts

immediately on escape of air.

• The system keeps the water

level constant despite of

movement of the vessel.


ACS trials

Resistance reduction

• The lubricated surface is

approx. 14% of the total

wetted surface

• Before correction for

roughness change the offset

is 8%

• Roughness correction is

around 2%

• After correction the offset is

around 6%


ACS trials

Conclusions after the tests of ACS Demonstrator

• The measured savings from

the trials confirms earlier

statements.

• The effect from the ACS is

scalable from model to

ships.

• The cavities are more stable

on the ship than on the

model.

• The cavities are possible to

control automatically.

• ACS Demonstrator is sailing

with the system under

normal operation.


ACS trials

Gaining efficiency for a big tanker vessel

• Main dimensions and block

coefficient.

• Propeller configuration

• Single screw geared

• Twin screw geared

• Single CRP

• Propeller type (CRP, NBS

Kappel or others)

• Wave resistance

• Air lubrication (ACS).

• Rudder configuration

• Treatment of bottom for

reducing roughness


ACS trials

Implementation of ACS to B-Max

Design Parameters and constrains

• DWT min. 200.000 t

• Length max. 225 m

• Breath max. 68 m

• Draft max. 14,5 m

• Service speed 15,5 knots.


ACS trials

The design principles for the B-Max

• Optimisation of main dimensions

• Best lines possible with the

constrains the design requires

• Low wave resistance

• Good wake field for the propeller

• Efficient propeller configuration

• Efficient machinery

The viscous CFD calculations are

conducted with the RANS code STAR-

CCM+ v3.02.006. STARCCM+ a finite

element volume code

The aim is to design as efficient

vessel as possible with known

technologies including ACS


ACS trials

Bow wave and wave resistance

Version A and B. Wave resistance lower in version B

The influence of inflow and displacement distribution.


ACS trials

Wave resistance and inflow to the propeller

Wave resistance and good inflow to the propeller.


ACS trials

Coefficients from the RANS CFD Analysis

Coefficients

Cf (friction)

Cr (residual)

Ca (allowance)

Ct (total)

Values x 10E3

1,654 81%

0,182 9%

0,200 10%

2,036 100%


Animation of boundary layer

ACS trials


ACS trials

Best Possible propeller

• RPM 92 (Conventional)

Diameter 7,50 m

Total efficiency 69%

• RPM 62 (Conventional - Geared)

Diameter 9,00 m


• RPM 55 (NBS - Geared)

Diameter 9,00 m


The normal for this type of vessel is

to install fixed propeller direct

coupled to the engine


ACS trials

Standard design - Efficient design

Resistance

Rudder

15% service

Propeller

Installed Power

Conv. Efficient

13.750 kW

14.010 kW

16.110 kW

23.350 kW

2 x 13,8 mW

ACS - Vessel

12.350 kW

12.350 kW

14.200 kW

18.950 kW

2 x 11,2 mW

Difference

-10%

-12%

-12%

-23%


ACS trials

Future – Research and Development

Compared to similar industries (the Car- or Air industry) the shipping

industry uses very little effort on Research and Development

Existing methods for evaluation and development of new designs are

“low tech” methods. New and better analysis tools are needed.

Development in new and more efficient propeller designs are almost non

existing. The “best” propeller is not found yet, know and more efficient

solution are not developed.

The solution for the industry is more research and development. The

ships can be more efficient but this requires new technology.

The market forces can not drive this, a helping hand is needed.


Thank you for your attention

For more information go to

www.dkgroup.eu

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