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Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project

Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project
Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project
Wind speed measurements obtained from anemometers mounted on ships are prone to systematic errors caused by the distortion of the airflow around the ship's hull and superstructure. This report describes the results of simulations of the airflow around the RRS James Clark Ross made using the computational fluid dynamics (CFD) software VECTIS. The airflow distortion at anemometer sites used during the WAGES project has been quantified at a wind speed of 10 m/s for relative wind directions of 0 (bow-on), 10, 20, 30, 50, 70, 90 and 110 degrees off the bow. The anemometers used in this study were located in the bows of the ship. Temperature sensors were located on the port side of the monkey island.

For bow-on flows the anemometers in the bows of the ship experienced relatively small flow distortion. At these sites the flow was decelerated by about 1% of the free stream wind speed. Over the full range of relative wind directions the flow to the R3 sonic is generally accelerated with the largest wind speed biases at flows directly over the beam. The vertical displacement of the airflow increases from around 1 to 2 m for flows directly over the bow, to around 5m for flows over the ships beam as the blockage of the airflow by the ship becomes greater.

The airflow distortion at the temperature sensor locations above the monkey island was typically greater than the well-exposed foremast locations. These locations experienced wind speed biases from 6% increase for an airflow directly over the bow, to large decelerations of 55 % when the instruments were in the large recirculation region for flows directly over the starboard side.
12
National Oceanography Centre
Moat, B.I.
497dbb18-a98f-466b-b459-aa2c872ad2dc
Yelland, M.J.
3b2e2a38-334f-430f-b110-253a0a835a07
Moat, B.I.
497dbb18-a98f-466b-b459-aa2c872ad2dc
Yelland, M.J.
3b2e2a38-334f-430f-b110-253a0a835a07

Moat, B.I. and Yelland, M.J. (2015) Airflow distortion at instrument sites on the RRS James Clark Ross during the WAGES project (National Oceanography Centre Internal Document, 12) Southampton, GB. National Oceanography Centre 85pp.

Record type: Monograph (Project Report)

Abstract

Wind speed measurements obtained from anemometers mounted on ships are prone to systematic errors caused by the distortion of the airflow around the ship's hull and superstructure. This report describes the results of simulations of the airflow around the RRS James Clark Ross made using the computational fluid dynamics (CFD) software VECTIS. The airflow distortion at anemometer sites used during the WAGES project has been quantified at a wind speed of 10 m/s for relative wind directions of 0 (bow-on), 10, 20, 30, 50, 70, 90 and 110 degrees off the bow. The anemometers used in this study were located in the bows of the ship. Temperature sensors were located on the port side of the monkey island.

For bow-on flows the anemometers in the bows of the ship experienced relatively small flow distortion. At these sites the flow was decelerated by about 1% of the free stream wind speed. Over the full range of relative wind directions the flow to the R3 sonic is generally accelerated with the largest wind speed biases at flows directly over the beam. The vertical displacement of the airflow increases from around 1 to 2 m for flows directly over the bow, to around 5m for flows over the ships beam as the blockage of the airflow by the ship becomes greater.

The airflow distortion at the temperature sensor locations above the monkey island was typically greater than the well-exposed foremast locations. These locations experienced wind speed biases from 6% increase for an airflow directly over the bow, to large decelerations of 55 % when the instruments were in the large recirculation region for flows directly over the starboard side.

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Published date: January 2015
Organisations: Marine Systems Modelling

Identifiers

Local EPrints ID: 373216
URI: http://eprints.soton.ac.uk/id/eprint/373216
PURE UUID: 91b18db8-122b-4add-a6de-56090ca66d1a

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Date deposited: 09 Jan 2015 11:20
Last modified: 14 Mar 2024 18:50

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Contributors

Author: B.I. Moat
Author: M.J. Yelland

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