Use of SimWAPS

Access to SimWAPS

SimWAPS is available at: https://www.craintechnologies.com/simwaps

Running a calculation

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Calculation cases are launched from the User Input Section on the left of the screen.

The calculation sequence is as follows:

  • Selection of a wind propulsion technology,

  • Adjustment of parameters for this technology,

  • Selection of a route, for which weather statistics have been previously calculated,

  • Selection of a ship type & adjustment of its characteristics,

  • Clic on the “submit” button

Each parameter can be adjusted within a defined range of values, depending on the selected wind propulsion technology. This flexibility make it possible to take account of variations in the performance of the same technology from one supplier to another.

Warning

The aim of SimWAPS is to evaluate the potential of differents solutions and to provide a preliminary estimate of the wind propulsion potential saving.

Please contact us to get a customized estimation of wind propulsion saving.

Default values are directly proposed for each parameter and each propulsion solution. These values are based on CRAIN aerodynamic experience. If in doubt, keep the default values, but feel free to vary them to see the influence of different parameters.

Throughout this process, contextual information popup info-bulle-ref will provide you with valuable assistance. Popups give a short definition of parameters and explain their influence on performance.

Finally, click on the Submit button, at the bottom of the input section to launch the calculations, which are instantly displayed on the results page :

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Description

1

Saving thanks to the use of wind propulsion expressed in various ways

2

Summary of calculation parameters

3

Chart of power saving as a function of true wind angle for various true wind speed

4

Button to export results as a pdf file

Saving is expressed as :

  • Average net power saving at the propeller shaft, in kW and per unit of area in kW/m2.

  • The ratio of net power saved to a reference propulsive power,

  • Average fuel saving in ton/day,

  • CO2 emission saving, considered from “tank to wake”.

Warning

This reference propulsive power is highly indicative. It is based on an estimate of ship resistance at the selected sailing speed.

Input data of SimWAPS

Wind Propulsion System (WAPS)

A WAPS is a wind propulsion system. It consists in a set of propulsion units (identical in SimWAPS).

For all technologies but kite, the aerodynamic performance of a WAPS unit is defined by the following parameters described in more detail in section IV.1:

  • CLmax: Maximum lift coefficient of one WAPS unit

  • Area and Span: Projected surface and Span of a unit of the off-pedestal system.

  • Number of devices: The number of identical units composing the WAPS.

The parameters for the kite are:

  • Operating CL : The coefficient of lift when the kite moves dynamically

  • Lift to Drag ratio: the aerodynamic finesse at the operating CL

  • Area: The developed wing surface

  • Elevation: the angle, in degrees, that makes the line of the kite with respect to the horizontal. The higher the angle, the more altitude the kite is flying.

Route

SimWAPS provides a sample of routes for which wind statistics have been calculated from historical meteorological data (ECMWF – ERA5).

A particular route is the “IMO route”, which corresponds the Global Wind Statistic Matrix defined by the International Maritime Organization (IMO) for the calculation the Energy Efficiency Design Index (EEDI). This is a fictitious route that represents the main routes used by commercial vessels.

Ship

The parameters that describe the vessel in SimWAPS are:

  • Length: the length of the vessel

  • Ship speed: the speed of the vessel

  • Beam: the width of the vessel

  • Draft: the draught of the vessel

  • Upper deck height: the height of the upper deck on which the propeller propulsion system is installed.

A drop-down menu is used to select a ship type. In this case, realistic parameters describing the vessel are proposed from the length of the vessel for each type. The type “Custom ship” allows the user to choose all the parameters himself.

Results

The results section indicates:

  • the average net power saved at the propeller shaft, expressed in kW for the entire system. For active systems, consumption has already been deducted.

  • the average net power saving per unit area of the entire system, expressed in kW/m2

  • the ratio of net power saving over a reference propulsive power, depending on the ship speed. This reference propulsive power, which is based on an rough estimate of the propulsive power demand of the ship, is very indicative, .

  • the average fuel savings, assuming a specific fuel consumption (SFOC) of 180 g/kWh,

  • the reduction of CO2 emissions, considered from “tank to wake”, is directly linked to the fuel consumption. Assuming a carbon content in mass of 85%, a typical value for marine fuel oil (such as VLSFO, MGO or HFO), the consumption of one ton of fuel oil rejects 3,1 tons of CO2 in the atmosphere.