ERIES-POLISHED

2023 - 2025

Wind Eng.

Stefanie Gillmeier

Anjali K.R. Jayakumari

Eric Roosenboom

Joao Muralha

Builherme Beleza Vaz

Felipe Sanchez Castro

2023 - 2025

Wind Eng.

Pollution, Atmospheric Boundary layer, Interaction and Ship Emission Data

ERIES-POLISHED

Pollutant dispersion

Ship aerodynamics

Dataset Description

The dispersion of pollutants exhausted from a generic service offshore vessel are investigated in the closed-circuit atmospheric boundary layer wind tunnel (ABLWT) at Eindhoven University of Technology. The vessel is replicated at a geometric scaling ratio of 1:100 and exposed to maritime neutral atmospheric flow conditions. For most measurements, an approach flow velocity of 10 m/s (full-scale) is set at the exhaust height.

The majority of conducted measurements relate to 25% of maximum continuous rating (MCR) engine load, which results in a release velocity of Ue = 8.8 m/s (full-scale). Emissions are released from an exhaust with circular shaft of 0.76 m in diameter (De). To match the densimetric Froude number (Fr) in experiments, and reality, a velocity scaling ratio of 1:10 is chosen for the wind tunnel measurements.

Main focus of pollutant concentration measurements is set on locations at 1.5 m height on the vessel’s deck to assess the possibility of workers’ exposure to emitted pollutants.

Measurements are valid for the following conditions:

• Standard atmospheric conditions (15 degrees Celsius and 1013.25 hPa), resulting in an ambient air density of ρa = 1.225 kg/m3.

• Emission temperature of 350 degrees Celsius (corresponding to an emission density of 0.567 kg/m3)

This results in a densymetric Froude number of Fr = 4.396069 (based on the diameter of the exhaust stack (De) and Ue = 8.8 m/s.

Pollutant Dispersion

Ship Emissions

Buoyant Release

Ship-Ship Interaction

Ship-Harbour Interaction

Specimens

1. Isolated ship

Measurements are conducted on a simplified generic offshore supply vessel. The real vessel has four exhaust shafts, located in close proximity to one another. For the wind tunnel experiments, such shafts are combined, and pollutants will only be released from one circular shaft of 0.76 m inner diameter. To emit pollutants from the stack, a pipe connection is printed as shown in the figures and the hull underneath is hollow to access the connection point with the supply tube. The STEP file containing the wind tunnel geometry is in model scale (1:100).

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1. Approach flow characterization

Neutral atmospheric flow conditions over sea are replicated in the wind tunnel at a geometric scaling ratio of 1:100. A combination of vortex generators and floor roughness elements is used to generate the desired flow conditions. The reference velocity, Uref, is defined as the time-averaged streamwise velocity component at the height corresponding to the center of the circular exhaust outlet above the WT floor.

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Instrumentation

The u, v, w (x, y, z) velocity components are measured using a Series 100 Cobra probe at a sampling frequency of 600 Hz for a duration of 60 s. An automatic traverse system is used to move the Cobra probe with an accuracy of better than 1 mm. Velocity measurements are taken at the center of the turntable at different heights (i.e., z =

0.01–1.00 m) above the WT floor.

2. Pollution dispersion measurements: Effect of ambient wind direction

Pollutants were release from the circular model exhaust shaft (De) with a release velocity of Ue = 8.8 m/s (full-scale). This results in a densymetric Froude number of Fr = 4.396069 (based on De and Ue). The ambient wind velocity was set to 10 m/s (full-scale) at exhaust shaft height.

Concentration measurements on the isolated vessel were conducted for five different approach flow directions (0, 345, 15, 90 and 180 degree). 34 measurement locations were distributed on deck of the vessel to investigate the effect of wind direction on the dispersion of exhausted pollutants.

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Instrumentation

An Ultra Sonic Anemometer (USA) located in the free stream to measure the approaching wind velocity to accurately set Uref. A 2-channel Cambustion HFR 400 Fast Flame Ionization Detector (FFID) was used to measure both the background ethylene concentration in the tunnel and the ethylene concentration received at measurement locations. At each location, a 300-second-long time series of pollutant concentrations was recorded. The sampling frequency of the accusition system was set to 1000Hz, due to the mechanical functioning of the FFID, the frequency physically resolvable is 85 Hz.

3. Pollution dispersion measurement: Effect of ambient wind velocity

For this experiment the approaching ambient wind velocity was increased, compared to the conditions described in experiment 1. Pollutants were still release from the circular model exhaust shaft (De) with a release velocity of Ue = 8.8 m/s (full-scale). The ambient wind velocity was set to 20 m/s (full-scale) at exhaust shaft height.

Concentration measurements were conducted for an approach flow directions of 0 degree at 34 measurement locations on deck of the vessel. To investiaget the effect of the ambient wind velocity on the dispersion of pollutants, results from this experiment shall be compared to results from the previous experiment (2) for the same appraoch flow direction.

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Instrumentation

Identical to the one descirbed for Experiment 2

4. Pollution dispersion measurement: Effect of exhaust velocity

For this experiment the release velocity of exhausted pollutants was increased, compared to the conditions described in experiment 1. Pollutants were release from the circular model exhaust shaft (De) with a release velocity of Ue = 26.4 m/s (full-scale), which corresponds to 75% MCR engine load. This results in a densymetric Froude number of Fr = 13.188207 (based on De and Ue). The ambient wind velocity was set to 10 m/s (full-scale) at exhaust shaft height.

Concentration measurements were conducted for an approach flow directions of 0 degree at 34 measurement locations on deck of the vessel. To investiaget the effect of the release velocity on the dispersion of pollutants, results from this experiment shall be compared to results from experiment 1 for the same appraoch flow direction.

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Instrumentation

Identical to the one descirbed for Experiment 2

2. Ship-ship interaction

Measurements are conducted on two simplified generic offshore supply vessel. The geometry and measurement locations are identical to the ones descirbed under SPECIMEN 1.

1. Approach flow characterization

Identical to the one descirbed for Specimen 1.

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Instrumentation

Identical to the one descirbed for Specimen 1

2. Pollution dispersion measurement: Effect of upstream ship

For this experiment, the ambient wind velocity was set to 10 m/s (full-scale) at exhaust shaft height. The downstream vessel was emitting pollutants from the circular model exhaust shaft (De) with a release velocity of Ue = 8.8 m/s (full-scale). This results in a densymetric Froude number of Fr = 4.396069 (based on De and Ue). The second vessel was located parallell to the emitting vessel at 100m (full-scale) upstream to investigate wake effects on the pollutant dispersion. Concentration measurements were conducted for an approach flow direction of 90 degree. Concentrations were measured on the downstream vessel at 34 measurement locations on deck of the vessel.

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Instrumentation

Identical to the one descirbed for Specimen 1, Experiment 2.

3. Pollution dispersion measurement on a trailing ship

For this experiment, the ambient wind velocity was also set to 10 m/s (full-scale) at exhaust shaft height. The upstream vessel was emitting pollutants from the circular model exhaust shaft (De) with a release velocity of Ue = 8.8 m/s (full-scale). Fr = 4.396069 (based on De and Ue). The second vessel was located 100m (full-scale) downstream of the emitting vessel to investigate the transporation of pollutants onto a vessel in the wake of the emitting vessel. Concentration measurements were conducted for several approach flow directions (e.g., 0, 15, 90, 345 degree). Concentrations were measured on the downstream vessel at 34 measurement locations on deck of the vessel. For the 90 degree appraoch direction, in addition, pollutant concentrations were measured on the downstream vessel, only 50 m (full-scale) apart.

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Instrumentation

Identical to the one descirbed for Specimen 1, Experiment 2.

3. Ship-harbour interaction

Measurements are conducted on a simplified generic offshore supply vessel, identical to the one described as SPECIMEN 1. In addition a simplified building model is added to the setup with the following reduced-scale dimensions: 1095 mm x 346 mm x 272 mm (length x width x height).

1. Approach flow characterization

Identical to the one descirbed for Specimen 1.

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Instrumentation

Identical to the one descirbed for Specimen 1.

2. Pollution dispersion measurement: Effect of proximity to a harbour structure

To investigate the effect a nearby building has on obtained pollutant concentration levels on a vessel's deck, a simplified building model was located at a distnace of 53.5 m (full-scale) from the vessel. In addition to the 34 measurement locations on deck of the vessel, pollutant concetraions were measured at additional 18 locations between vessel and building. Measurements were conducted for an appraoch flow direction of 0 degree and 90 degree. For the latter, the building model was located upstream and downstream of the vessel. Results from this experiment can be compared to results of the isolated vessel (for corresponding appraoch flow angles) to assess the effect a neighboring harbour building structure may have on the pollutant dispersion. The 18 additional measurement locations are also existinging in the corresponding dataset of the isolated vessel.

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