1 AIR LUBRICATION SYSTEM (CATEGORY (B-1))
1.1 Summary of innovative energy efficient technology
1.1.1 An air lubrication system is one of the innovative energy efficiency technologies.
Ship frictional resistance can be reduced by covering the ship surface with air bubbles,
which is injected from the fore part of the ship bottom by using blowers, etc.Ship
frictional resistance can be reduced by covering the ship surface with air bubbles,
which
Figure 1 – Schematic illustration of an air lubrication system
1.2 Method of calculation
1.2.1 Power reduction due to air lubrication system
1.2.1.1 Power reduction factor Peff due to an air lubrication
system as an innovative energy efficiency technology is calculated by the following
formula. The first and second terms of the right hand side represent the reduction of
propulsion power by the air lubrication system and the additional power necessary for
running the system, respectively. For this system, feff is 1.0
in EEDI formula.
|
|
(1)
|
| * In the case of PPTI(i)
>0, the average weighted value of (SFCME
∙CFME
) and (SFCAE ∙ CFAE
)
|
1.2.1.2 Peff
is the effective power reduction in kW due to the air lubrication system at the 75%
t of the rated installed power (MCR). In case that shaft generators are installed,
Peff
should be calculated at the 75% MCR having after deducted any installed shaft
generators in accordance with paragraph 2.2.5 of EEDI Calculation Guidelines.
Peff
should be calculated both in the fully loaded and the sea trial conditions.
1.2.1.3 PPeffAL
is the reduction of propulsion power due to the air lubrication system in kW.
PPeffAL
should be calculated both in the condition corresponding to the Capacity as
defined in EEDI Calculation Guidelines (hereinafter referred to as "fully loaded
condition") and the sea trial condition, taking the following items into account:
-
.1 area of ship surface covered with air;
-
.2 thickness of air layer;
-
.3 reduction rate of frictional resistance due to the
coverage of air layer;
-
.4 change of propulsion efficiency due to the
interaction with air bubbles (self propulsion factors and propeller open water
characteristics); and
-
.5 change of resistance due to additional device, if
equipped.
1.2.1.4 PAEeffAL
is additional auxiliary power in kW necessary for running the air lubrication
system in the fully loaded condition. PAEeffAL
should be calculated as 75% of the rated output of blowers based on the
manufacturer's test report. For a system where the calculated value above is
significantly different from the output used at normal operation in the fully loaded
condition, the PAEeffAL
value may be estimated by an alternative method. In this case, the calculation
process should be submitted to a verifier.
1.2.2 Points to keep in mind in calculation of attained EEDI with air lubrication
system
1.2.2.1 Vref
in paragraph 2.2.2 of EEDI Calculation Guidelines should be calculated in the
condition that the air lubrication system is OFF to avoid the double count of the effect
of this system.
1.2.2.2 In accordance with EEDI Calculation Guidelines, the EEDI value for
ships for the air lubrication system ON should be calculated in the fully loaded
condition.
1.3 Method of verification
1.3.1 General
1.3.1.1 Attained EEDI for a ship with an innovative energy efficient technology should
be verified in accordance with EEDI Survey Guidelines. Additional information on the
application of air lubrication system, which is not given in the EEDI Survey Guidelines,
is contained below.
1.3.2 Preliminary verification at the design stage
1.3.2.1 In addition to paragraph 4.2.2 of EEDI Survey Guidelines, the EEDI
Technical File which is to be developed by a shipowner or shipbuilder should
include:
-
.1 outline of the air lubrication system;
-
.2
PPeffAL
: the reduction of propulsion power due to the air lubrication system at the
ship speed of Vref
both in the fully loaded and the sea trial conditions;
-
.3
EDRfull
: the reduction rate of propulsion power in the fully loaded condition due to
the air lubrication system. EDRfull
is calculated by dividing PMEeffAL
by PME
in EEDI Calculation Guidelines in the fully loaded condition (see figure 2);
-
.4
EDRtrial
: the reduction rate of propulsion power in a sea trial condition due to the
air lubrication system. EDRtrial
is calculated by dividing PMEeffAL
by PME
in EEDI Calculation Guidelines in sea trial condition (see figure 2);
Figure 2 – Calculation of the reduction rate of propulsion power
(EDRfull and EDRtrial) due to air
lubrication system
-
.5
PAEeffAL
: additional power necessary for running the air lubrication system; and
-
.6 the calculated value of the EEDI for the air
lubrication system ON in the fully loaded condition.
1.3.2.2 In addition with paragraph 4.2.7 of the EEDI Survey Guidelines,
additional information that the verifier may request the shipbuilder to provide directly
to it includes:
-
.1 the detailed calculation process of the reduction
of propulsion power due to the air lubrication system: PPeffAL
; and
-
.2 the detailed calculation process of the additional
power necessary for running the air lubrication system: PAEeffAL
.
1.3.3 Final verification of the attained EEDI at sea trial
1.3.3.1 Final verification of the EEDI of ships due to the air lubrication
system should be conducted at the sea trial. The procedure of final verification should
be basically in accordance with paragraph 4.3 of the EEDI Survey Guidelines.
1.3.3.2 Prior to the sea trial, the following documents should be submitted
to the verifier; a description of the test procedure that includes the measurement
methods to be used at the sea trial of the ship with the air lubrication system.
1.3.3.3 The verifier should attend the sea trial and confirm the items
described in paragraph 4.3.3 of the EEDI Survey Guidelines to be measured at the sea
trial for the air lubrication system ON and OFF.
1.3.3.4 The main engine output at the sea trial for the air lubrication
system ON and OFF should be set so that the range of the developed power curve includes
the ship speed of Vref
.
1.3.3.5The following procedure should be conducted based on the power curve
developed for air lubrication system OFF.
-
.1 ship speed at 75% MCR of main engine in the fully
loaded condition, Vref
, sshould be calculated. In case that shaft generators are installed,
Vref
should be calculated at 75% MCR having after deducted any installed shaft
generators in accordance with paragraph 2.2.5 of EEDI Calculation Guidelines;
and
-
.2 In case that Vref
obtained above is different from that estimated at the design stage, the
reduction rate of main engine should be recalculated at new Vref
both in the fully loaded and the sea trial conditions.
1.3.3.6 The shipbuilder should develop power curves for the air lubrication
system ON based on the measured ship speed and output of the main engine at the sea
trial. The following calculations should be conducted.
-
.1 The actual reduction rate of propulsion power
ADRtrial
at the ship speed of Vref
at the sea trial.
-
.2 if the sea trial is not conducted in the fully
loaded condition, the reduction rate of propulsion power in this condition should
be calculated by the following formula:
-
i.e.
|
(2)
|
|
Figure 3 – Calculation of the actual reduction rate of propulsion
power (ADRfull and ADRtrial) due to air
lubrication system
1.3.3.7 The reduction of propulsion power due to the air lubrication system
PMEeffAL
in the fully loaded and the sea trial conditions should be calculated as follows:
-
|
PPeffAL_Full = ADRFull
X PP
|
(3)
|
|
PPeffAL_Trial = ADRTrial
X PP
|
(4)
|
1.3.3.8 The shipowner or the shipbuilder should revise the EEDI Technical
File, as necessary, by taking the result of the sea trial into account. Such revision
should include the following contents:
-
.1
Vref
, in case that it is different from that estimated at the design stage;
-
.2 the reduction of propulsion power
PPeffAL
at the ship speed of Vref
in the fully loaded and the sea trial conditions for the air lubrication
system ON.
-
.3 the reduction rate of propulsion power due to air
lubrication system (ADRfull
and ADRtrial
) in the fully loaded and the sea trial conditions.
-
.4 the calculated value of the EEDI for the air
lubrication system ON in the fully loaded condition.
2 WIND ASSISTED PROPULSION SYSTEM (CATEGORY B-2)
2.1 Summary of innovative energy efficient technology
2.1.1 Wind propulsion systems belong to innovative mechanical energy
efficient technologies which reduce the CO2 emissions of ships. There are
different types of wind propulsion technologies (sails, wings, kites, etc.) which
generate forces dependent on wind conditions. This technical guidance defines the
available effective power of WAPS as the product of the reference speed and the sum of
the wind assisted propulsion system force and the global wind probability
distribution.
2.1.2 Secondary effects when applying the wind assisted propulsion system which might
increase the ship resistance are ignored for the purpose of these guidelines. With this
simplification effects as for instance additional drag due to leeway, rudder angle and
heel or reduced propeller efficiency in light running condition are ignored without
significant loss of accuracy. Nonetheless, the corresponding forces are considered to
rule out conditions that do not allow a safe operation of the ship, for instance due to
exceeding heel angles.
2.2 Definitions
2.2.1 For the purpose of these guidelines, the following definitions should
apply:
-
.1 available effective power is the multiplication of
effective power Peff and availability factor feff as defined
in the EEDI calculation.
-
.2 wind assisted propulsion systems (WAPS) belong to innovative
mechanical energy efficient technologies which reduce the CO2 emissions
of ships. These proposed guidelines apply to wind propulsion technologies that
directly transfer mechanical propulsion forces to the ship's structure (sails,
wings, kites, etc.);
-
.3 wind propulsion system force matrix is a two-dimensional
matrix which expresses the force characteristic of a wind assisted propulsion
system dependent on ship speed, wind speed and the wind angle relative to
heading;
.4 global wind probability matrix contains data of the global wind power on
the main global shipping routes based on a statistical survey of worldwide wind
data and represents the probability of wind conditions;
.5 wind speed is the speed of the wind in m/s measured at 10 m above sea
level;
.6 wind direction is the North-oriented direction of the wind measured at
10 m above sea level and is subdivided into eight sectors (North, North-East,
East, South-East, South, South-West, West, North-West);
.7 wind angle is the angle of the wind relative to the ship's heading at 10
m above sea level subdivided into 72 sectors of 5°-steps (0°, 5°,..., 355°);
and
.8 the main global shipping network is a network of global shipping routes
with the highest frequency of journeys.
2.3 Available effective power of wind assisted propulsion systems (WAPS)
2.3.1 The available effective power of wind propulsion systems as
innovative energy efficient technology is calculated by the following formula:
-
- with F1 - Fk ≥ 0 ∧ Fk-1 – Fk ≥
0
-
and 
-
Where:
-
.1 (feff * Peff) is the
available effective power in kW delivered by the specified wind propulsion system.
feff and Peff are combined in the calculation because the
product of availability and power is a result of a matrix operation, addressing
each wind condition with a probability and a specific wind propulsion system
force;
-
.2 The factor 0.5144 is the conversion factor from
nautical miles per hour (knots) to metres per second (m/s);
-
.3 Vref is the ship reference speed
measured in nautical miles per hour (knots), as defined in the EEDI calculation
guidelines.
-
.4 ηD is the total efficiency of the main
drive(s) at 75 per cent of the rated installed power (MCR) of the main engine(s).
ηD shall be set to 0.7, if no other value is specified and verified
by the verifier;
-
.5 F(Vref)k is the force matrix
of the respective wind assisted propulsion system for a given ship speed
Vref. Each matrix element represents the propulsion force in kilo
newton (kN) for the respective wind speed and angle. The wind angle is given in
relative bearings (with 0° on the bow);
-
.6 Wk is the global wind probability
matrix. Each matrix element represents the probability of wind speed and wind
angle relative to the ships heading. The sum over all matrix elements equals 1 and
is non-dimensional; and
-
.7 P(Vref)k is a matrix with
the same dimensions as F(Vref)k and Wk and
represents the power demand in kW for the operation of the wind assisted
propulsion system.
2.3.2 The fore term of the formula defines the additional propulsion power
to be considered for the overall EEDI calculation. The term contains the product of the
ship specific speed, the force matrix and the global wind probability matrix. The aft
term contains the power requirement for the operation of the specific wind assisted
propulsion system which has to be subtracted from the gained wind power.
2.4 Wind propulsion system force matrix F(Vref)k
2.4.1 Measurement of the wind propulsion coefficients
2.4.1.1 The wind propulsion system force matrix is a table describing the
average wind propulsion coefficients corresponding to the global wind probability
matrix. Therefore, the measurement of the wind propulsion coefficients has to be carried
out at first in order to obtain the wind propulsion system force matrix.
2.4.1.2 Various methods can be used to determine the aerodynamic forces of a
wind assisted ship, depending firstly on the type of wind assisted propulsion system,
but also size limitations and successful validation for the methods already shown in
literature. The methods include:
2.4.1.3 The forces are to be determined for the combination of wind assisted propulsion
system and ship unless that is not practical due to technical or economic reasons. In
the latter case the conditions of 2.4.1.4 apply.
2.4.1.4 In the case of the installation of multiple wind assisted propulsion systems,
the forces may be determined for the devices in isolation and by the summing the
coefficients of each units comprising the system, provided that a validated method is in
place to account for interaction effects between wind propulsors and between the ship
and the wind propulsors.
2.4.1.5 Wind propulsion devices are to be analysed at their operational Reynolds number,
as this has been shown to affect their performance.
2.4.1.6 The wind tunnel model test is a major method for measuring the aerodynamic force
of a wind assisted ship propulsion system under typical states. Appendix 1 of this annex
describes the testing methods of wind tunnel model tests. If the wind propulsion
coefficients are measured by the wind tunnel model test, it should be conducted in
accordance with the appendix 1.
2.4.1.7 For some types of wind assisted propulsion system wind tunnel model tests are
not appropriate for measuring the wind propulsion coefficients. Therefore, numerical
calculations, such as CFD-computation, can be accepted for estimating the wind
propulsion coefficients, but the condition and the model of the numerical calculation
should be referred to experimental representative results and the numerical calculation
is to be carried out in accordance with defined quality and technical standards (ITTC
7.5-03-01-02 and ITTC 7.5-03-01-04 at their latest revisions or equivalent). If both of
wind tunnel model tests and numerical calculation are inappropriate to estimate the
coefficient, other testing method may be acceptable with the approval of the verifier.
2.4.1.8 When a test or calculation for determining the wind propulsion coefficients is
carried out, the procedure of the test or calculation should be submitted to the
verifier in advance of conducting the test or calculation. In addition, the detail
report of the test and calculation procedure should also be submitted to the verifier
after the test. The verifier may request the submitter to provide further
documents/information as necessary to verify the wind propulsion coefficients.
2.4.1.9 The test of a ship model without wind assisted propulsion system mainly measures
the wind forces of the ship model pointing to the bow under different wind directions.
The test of a ship model with wind assisted propulsion system mainly measures the
maximum wind propulsion of the ship model pointing to the bow under different wind
directions, which is then used to calculate the wind propulsion coefficient of the wind
propulsion system. The coefficients of the wind assisted propulsion system should be
determined at a series of wind angles ranging from 0° to 360°, spaced by an interval of
5°.
2.4.1.10 A single wind tunnel test may be accepted for several identical wind assisted
propulsion systems and identical ships. The verifier may request that supporting
documentation be produced.
2.4.2 Wind tunnel test methods and data processing
Option 1: Test on a ship model fitted with the full wind assisted propulsion
system
2.4.2.1 When the wind tunnel test is carried out with the ship model and the wind
assisted propulsion system model, the test method should follow the specifications given
in appendix 1. The wind forces acting on the ship model are normalized as:
2.4.2.2 The wind propulsion coefficientsfootnote of the wind assisted propulsion system can be determined
as:
-
ΔCFx = CFx-with WPS - CFx-without
WPS
-
Where:
-
.1 CFx is the wind force coefficient of the model pointing to
the bow;
-
.2 Fx is the wind force of the model pointing to the bow;
-
.3 ΔCFx is the wind propulsion coefficient of the wind assisted
propulsion system;
-
.4 ⍴ is the air density of the model test;
-
.5 V is the wind velocity of the model test;
-
.6 A is the total projected area of the wind assisted propulsion system; and
-
.7 the subscript "with WAPS" means the state with wind assisted propulsion system
of the ship model, while "without WAPS" means the state without wind assisted
propulsion system of the ship.
Option 2: Test with a single wind assisted propulsion unit
2.4.2.3 When the wind tunnel test is carried out with a single wind propulsion unit, the
test method should follow the specifications given in appendix 1. The wind propulsion
coefficientsfootnote of the model can be determined as:
-
CFx = Fx / (0.5 ⍴ V2 A)
-
Where:
-
.1 CFx is the wind force coefficient of the model pointing to
the bow;
-
.2 Fx is the wind force of the model pointing to the bow;
-
.3 ⍴ is the air density of the model test;
-
.4 V is the wind velocity of the model test; and
-
.5 A is the total projected area of the wind assisted propulsion system.
2.4.2.4 The wind propulsion coefficients ΔCFx of a multi-unit
wind assisted propulsion system can be calculated by summing the coefficients of the
units comprising the system, weighted by the effects of interaction and masking by
superstructures.
For options 1 and 2: Calculation of the average power consumption coefficients of
the active wind assisted propulsion system during the wind tunnel test
2.4.2.5 The power consumption of the wind assisted propulsion system should be measured
and the power consumption matrix should be filled based on the measured values and the
systems control plan.
2.4.3 Calculation of the wind propulsion system force matrix
2.4.3.1 The wind propulsion coefficientsfootnote of the ship's wind assisted propulsion system can be used
to predict the wind propulsion system force matrix. Apparent wind is defined as the
combination of wind relative to the ground and wind created by the ship's velocity. The
steps to calculate the wind propulsion system force matrix are as follows:
-
.1 determine the velocity of the ship Vref;
-
.2 select the average wind speed corresponding to terms in Wk, the
global wind probability matrix at 10 m height. For example, the average wind speed
corresponding to the first wind speed range (0-1 m/s) of the wind probability
matrix is selected as 0.5 m/s, the average wind speed corresponding to the second
wind speed range (1-2 m/s) is selected as 1.5 m/s, etc.;
-
.3 extrapolate the wind speed to the reference height of the wind assisted
propulsion systems taken as the aerodynamic centre of effort height or half height
from the waterline:
-
Where:
-
-
.1 zref is the reference height above the water line, to be equal
to the point of mid-height of each sail, Flettner, etc. in wind assisted
propulsion system;
-
.2 v10m is the wind velocity at 10 m above sea level;
-
.3 vZref is the resulting wind velocity at the reference height;
and
-
.4 α is taken as 1/9 conforming to ITTC recommendations.footnote
-
.4 according to the corresponding average wind speed, wind direction angle and the
velocity of the ship, calculate the relative wind speed Vk and the
relative wind direction angle of the ship;
-
.5 according to the relative wind direction angle, and the corresponding
relationship between the relative wind direction angle and the wind propulsion
coefficient ΔCFx obtained from the test, calculate the average
wind propulsion coefficients (ΔCFx)k of the wind
assisted propulsion system corresponding to Wk; and
-
.6 according to the average wind propulsion coefficient of the wind assisted
propulsion system, calculate the terms of the wind propulsion system force matrix
F(Vref)k of the full scale ship corresponding to
Wk by following formula:
-
-
F(Vref)k = (ΔCFx)k * (0.5
⍴ Vk2 A)
-
Where:
-
.1 (ΔCFx)k is the average wind propulsion
coefficients corresponding to Wk;
-
.2 ⍴ is the average air density in shipping environment, ⍴=1.225
kg/m3;
-
.3 Vk is the relative wind velocity of the full-scale ship
corresponding to Wk;
-
.4 A is the total projected area of the wind assisted propulsion system;
-
.5 the settings of the wind propulsor may be varied in order to find the
best (ΔCFx)k; this may be done using interpolation
provided that increments in settings are sufficiently small;
-
.6 the settings and deployment of the wind assisted propulsion system must
adhere to the operational constraints as defined for the system (e.g. a
maximum operational wind speed, if lower than provided by the global wind
probability matrix, > Bf 8, 19 m/s);
-
.7 the potential wind drag induced by the system is to be accounted for,
such as in unusable wind directions close to head wind and when the systems
is not operational due to exceedance of operational limits; and
-
.8 if F(Vref)k exceeds the resistance of the ship,
such that the propeller thrust would be negative,
F(Vref)k is to be limited at the resistance value.
2.4.4 Consideration of the operational limits of the wind assisted propulsion system
and the lateral forces and yawing moments
2.4.4.1 Force F(Vref)k must be calculated only when
it is within the operational domain applicable to the wind assisted propulsion system.
These operational limitations can be caused at a minimum by wind conditions or by the
total forces generated by the wind assisted propulsion system and applied to the ship.
2.4.4.2 F(Vref)k must be zero for any pair (wind
direction; wind force) not in conformity with the operational domain of the wind
assisted propulsion system validated by the verifier in the operations manual of the
wind assisted propulsion system and the ship.
2.4.4.3 The lateral forces exerted by the wind assisted propulsion system on the ship
and the resulting yawing moment can affect the performance of the system, and therefore
the EEDI calculation. The lateral forces on the ship and the yawing moments applied by
the wind assisted propulsion system to the ship should therefore be documented by the
shipbuilder and/or propulsion system manufacturer and observed by the verifier. They can
be obtained without additional effort during the tests described in paragraph 2.4.1 of
the present circular.
2.4.4.4 Conformity with the operational domain requires that for any pair (wind
direction; wind force), and in consideration of the total forces generated by the wind
assisted propulsion system (i.e. including lateral forces to the vessel and yawing
moments), the strength of the wind assisted propulsion system, the forces at the
embedment and the list of the ship conform with the structural design file and the
stability file of the ship, respectively. Where the lateral forces and yawing moment are
particularly significant, the verifier may request course keeping and rudder angle
demonstrations to validate conformity with the operational domain.
2.5 The global wind probability matrix Wk
2.5.1 Wind probabilities
2.5.1.1 Wind conditions are not constant. Winds vary their speed and direction with
time. Wind expectations are unequal in different regions of the earth.
2.5.1.2 However, every wind expectation can be expressed in a distinctive wind
probability pattern for every particular position on the globe. There is always a
certain probability for a certain wind direction and wind speed to occur. These
probabilities are documented in wind charts. With this approach each geographical region
has a distinctive wind chart.
2.5.2 Wind angles relative to the ship
2.5.2.1 For a wind assisted propulsion system, it is irrelevant if the wind
is coming from North or South. Only the wind angle relative to a shipʹs heading is of
importance. As a consequence, the wind directions given in the weather data have to be
recalculated for ship headings on a trading route when applied to wind assisted
propulsion systems, where 0° means the ship's bow, 90° its starboard side, 180° the
stern and 270° port side.
2.5.3 Main global shipping network
2.5.3.1 To determine a global wind probability chart for the wind assisted propulsion
systemʹs EEDI calculation, the average of all wind conditions along the main global
shipping routes is required.
2.5.3.2 Figure 1 shows the main global shipping network used to determine the global
wind conditions. Along the shown routes, 106 wind condition charts were analysed. These
charts are based on 868,500 individual wind data.
2.5.3.3 The wind condition charts for each position were first recalculated in ship
heading coordinates and then averaged to form a global wind condition chart. The results
are visualized in figure 2, the complete chart (the global wind probability matrix) is
shown as the table in appendix 2 of this annex.
2.5.3.4 Each element of the matrix Wk represents the probability of the specific wind
speed and wind angle relative to the ship. The sum of all matrix elements is one (1.0),
representing 100% of all wind conditions.
2.5.3.5 The results show that winds to the bow or the stern occur more often than winds
to the sides. There are two possible reasons to explain this phenomenon:
-
.1 shipping routes and global weather systems are more East-West than North-South
oriented; and
-
.2 shipping routes and winds are influenced by shore lines, so they tend to be
parallel in some regions.
Figure 1 – The main global shipping network used for the wind chart
Figure 2 – Resulting wind curves on the main global shipping routes relative to
the ship
2.6 Effective CO2 reduction by wind assisted propulsion systems
2.6.1 For the calculation of the CO2 reduction, the resulting available
effective power (feff * Peff) has to be multiplied with the
conversion factor CFME and SFCME , as contained in the original
EEDI formula.
2.7 Verification of wind assisted propulsion systems in the EEDI certification
process
2.7.1 General
2.7.1.1 Verification of EEDI with innovative energy efficient technologies should be
conducted according to the EEDI Survey Guidelines. Additional items concerning
innovative energy efficient technologies not contained in EEDI Survey Guidelines are
described below.
2.7.2 Preliminary verification at the design stage
2.7.2.1 In addition to paragraph 4.2.2 of EEDI Survey Guidelines, the EEDI Technical
File which is to be developed by the shipowner or shipbuilder should include:
2.7.2.2 In addition to paragraph 4.2.7 of the EEDI Survey Guidelines, additional
information from the shipbuilder may be requested by the verifier. It includes:
2.7.2.3 In order to prevent undesirable effects on the ship's structure or main drive,
the influences of added forces on the ship should be determined during the EEDI
certification process. Elements in the wind propulsion system force matrix may be
limited to ship specific restrictions, if necessary. The technical means to restrict the
wind propulsion system's force should be verified as part of the performance test.
2.7.2.4 If more than one innovative energy efficient technology is subject to approval
in the EEDI certification, interactions between these technologies should be considered.
The appropriate technical papers should be included in the additional information
submitted to the verifier in the certification process.
2.7.3 Final verification of the attained EEDI
2.7.3.1 The total net power generated by wind assisted propulsion systems should be
confirmed based on the documentation in the EEDI Technical File. For final verification,
EEDI verifier should check that the configuration of the installed wind assisted
propulsion system agrees with the system as described in the EEDI Technical File.
Appendix 1 – Method of Wind Tunnel Model Test
In accordance with section 2.4.1 of the present circular, two test methods are defined:
Option 1: Test on a ship model fitted with the full wind assisted propulsion
system
1 Model
1.1 The wind assisted propulsion system model and the hull model should be made
similarly to the real form, but appendages which do not affect the aerodynamic
characteristics can be omitted from the model (e.g. handrails, windlass, etc.).
1.2 The draught condition of the hull model should be corresponding to the Capacity as
defined in EEDI Calculation Guidelines.
1.3 The hull model is connected with the turntable by force balance, and the wind
direction angle of the ship model is changed by changing the angle of the turntable.
2 Test condition
2.1 In addition to geometric similarity, the dynamic similarity criterion must be
satisfied in the wind matrix wind tunnel model test of a ship's wind assisted propulsion
system. That is, when the test wind speed is higher than a certain critical wind speed,
the dimensionless wind coefficient tends to be stable, and the flow around the model is
similar to the real ship. The measured wind coefficient can be directly extrapolated to
the real ship. During the test, the critical wind speed is determined by a variable wind
speed test.
2.2 In the wind tunnel model test, spires and roughness elements are arranged at the
front of the test section, and the wind field of the atmospheric boundary layer on the
ocean surface at the model scale for wind matrix test is obtained. Reynolds number of
the test should be more than 1.0 x 106. The Reynolds number, Re, is
expressed by the following formula:
μ
where ρ and μ are the density and viscosity of the air, respectively,
U is the wind speed, Lpp is the length between
perpendiculars of the model ship.
2.3 The blockage ratio should not be more than 5%. The ratio is calculated by the
transverse projected area of the model divided by the cross-sectional area of wind
tunnel.
3 Test method
3.1 At the same hull wind direction, the wind propulsion coefficients of the wind
assisted propulsion system are different at different angles of attack. In order to
obtain the maximum wind propulsion coefficients of the wind assisted propulsion system
at each hull wind direction angle, the test scheme should include:
-
.1 measurements of the aerodynamic force characteristics of the ship model without
wind assisted propulsion system at a series of wind angles ranging from 0° to
360°, spaced by an interval of 5°, potentially extended to 10° only for beam to
stern;
-
.2 measurements of the aerodynamic force characteristics of the ship model with
wind assisted propulsion system at a series of wind angles ranging from 0° to
360°, spaced by an interval of 5° or 10°, attack angles of the wind assisted
propulsion system range from 0° to 180°, spaced by an interval of 5° or 10° in
every wind angle of the ship model. Smaller intervals of attack angles should be
needed around the maximum wind propulsion coefficients; and
-
.3 in the case where the measurements are carried out with spaced by
an interval of 10°, each intermediate force characteristic (i.e. FX at
5°, 15°, 25°…) should be interpolated by using the measurement results.
3.2 In the case where the shape of the ship and wind assisted propulsion system are
symmetrical on starboard side and port side, the wind propulsion coefficients are also
symmetrical and thus, the measurements at a series of wind angles ranging from 0° to
180° or 180° to 360° can be omitted.
3.3 If the wind assisted propulsion system has a changeable and controllable structure,
such as sails and rotors, the model of the wind assisted propulsion system can be
arranged as the wind angle, the rotor speed, or other controllable structure to maximize
the gained wind force or to minimize the wind resistance.
Option 2: Test on a complete model of a single wind propulsion unit
4 Model
4.1 The effects of the hull and superstructures should be taken into account by
corrective actions taking into account the masked area and distance. If several wind
propulsion units are installed on board the ship, the aerodynamic interactions between
them should be taken into account by corrective actions. The verifier may request
documentation from the test author to verify that these effects have been taken into
account.
4.2 The wind propulsion unit model is connected to the turntable by means of a force
balance, and the wind direction angle of the ship model is changed by changing the angle
of the turntable.
5 Test conditions
5.1 In addition to geometric similarity, the dynamic similarity criterion must be
satisfied in the wind matrix wind tunnel model test of a shipʹs wind assisted propulsion
system. That is, when the test wind speed is higher than a certain critical wind speed,
the dimensionless wind coefficient tends to be stable, and the flow around the model is
similar to the real ship. The measured wind coefficient can be directly extrapolated to
the real ship. During the test, the critical wind speed is determined by a variable wind
speed test.
5.2 The maximum Reynolds number of the test should be more than 5.0 x 105.
The Reynolds number, Re, is expressed by the following formula:
-
Re = ρ . U . C / μ
where ρ and μ are the density and viscosity of the air, respectively, U is the
wind speed, C is the mean chord length of the wind propulsion unit.
5.3 The blockage ratio should not be more than 5%. The ratio is calculated by the
transverse projected area of the model divided by the cross-sectional area of wind
tunnel.
6 Test method
6.1 In order to obtain the maximum wind propulsion coefficients of the wind assisted
propulsion system at each ship wind direction angle, the test scheme should include
measurements of the aerodynamic force characteristics for:
-
.1 a range of permissible angles of attack on the wind propulsion unit; and
-
.2 a range of permissible settings (profile camber, rotation speed, suction rate,
reduced area, etc.).
6.2 The propulsive force on the ship is the aerodynamic force measured on the wind
propulsion unit pointing to the bow.
Appendix 2 – Global Wind Probability Matrix Wk
Table 1 – Normalized global wind chart showing the probability of wind conditions
relative to the shipʹs heading along the main global trading routes
