Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines
The research problem discussed in this paper is of relevance to floating offshore wind turbine design, where heave plates are attached to the columns of a semi-submersible in order to improve vertical plane stability and the power output. Because of the shallow draft of these structures, the heave p...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-08-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/8/8/622 |
| _version_ | 1827709073479434240 |
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| author | Krish Thiagarajan Javier Moreno |
| author_facet | Krish Thiagarajan Javier Moreno |
| author_sort | Krish Thiagarajan |
| collection | DOAJ |
| description | The research problem discussed in this paper is of relevance to floating offshore wind turbine design, where heave plates are attached to the columns of a semi-submersible in order to improve vertical plane stability and the power output. Because of the shallow draft of these structures, the heave plates are proximal to the water surface. When subject to vertical plane motions the flow around a plate is altered by the presence of the free surface, resulting in changes in added mass and damping forces. In this paper, we present the experimental results for the added mass and damping coefficients for circular heave plates attached to a column, when oscillating in heave in the presence of oncoming waves. The results tend to indicate that applying the hydrodynamic coefficients obtained from still water experiments for a structure moving in waves may only be an approximation. For different relative phases of the wave and the motion, large variations could occur. We define a modified Keulegan—Carpenter (<inline-formula><math display="inline"><semantics><mrow><mi>K</mi><mi>C</mi></mrow></semantics></math></inline-formula>) number that depends on the relative amplitude of motion with respect to the wave. With this definition, the added mass and damping values are seen to be closer to the still water trends. However, at lower <inline-formula><math display="inline"><semantics><mrow><mi>K</mi><mi>C</mi></mrow></semantics></math></inline-formula> values, the added mass coefficients could differ by 30%, which can affect natural frequency estimates. Thus, caution needs to be exerted in the selection of hydrodynamic coefficients for heave plates oscillating in proximity to the free surface. |
| first_indexed | 2024-03-10T17:15:53Z |
| format | Article |
| id | doaj.art-08a837572274408b81ee8aff8771ed39 |
| institution | Directory Open Access Journal |
| issn | 2077-1312 |
| language | English |
| last_indexed | 2024-03-10T17:15:53Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Journal of Marine Science and Engineering |
| spelling | doaj.art-08a837572274408b81ee8aff8771ed392023-11-20T10:29:22ZengMDPI AGJournal of Marine Science and Engineering2077-13122020-08-018862210.3390/jmse8080622Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind TurbinesKrish Thiagarajan0Javier Moreno1Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA 01007, USAMarflet Marine, 28014 Madrid, SpainThe research problem discussed in this paper is of relevance to floating offshore wind turbine design, where heave plates are attached to the columns of a semi-submersible in order to improve vertical plane stability and the power output. Because of the shallow draft of these structures, the heave plates are proximal to the water surface. When subject to vertical plane motions the flow around a plate is altered by the presence of the free surface, resulting in changes in added mass and damping forces. In this paper, we present the experimental results for the added mass and damping coefficients for circular heave plates attached to a column, when oscillating in heave in the presence of oncoming waves. The results tend to indicate that applying the hydrodynamic coefficients obtained from still water experiments for a structure moving in waves may only be an approximation. For different relative phases of the wave and the motion, large variations could occur. We define a modified Keulegan—Carpenter (<inline-formula><math display="inline"><semantics><mrow><mi>K</mi><mi>C</mi></mrow></semantics></math></inline-formula>) number that depends on the relative amplitude of motion with respect to the wave. With this definition, the added mass and damping values are seen to be closer to the still water trends. However, at lower <inline-formula><math display="inline"><semantics><mrow><mi>K</mi><mi>C</mi></mrow></semantics></math></inline-formula> values, the added mass coefficients could differ by 30%, which can affect natural frequency estimates. Thus, caution needs to be exerted in the selection of hydrodynamic coefficients for heave plates oscillating in proximity to the free surface.https://www.mdpi.com/2077-1312/8/8/622heave platefree surface effectfloating offshore wind turbinehydrodynamic coefficientsadded massdamping coefficient |
| spellingShingle | Krish Thiagarajan Javier Moreno Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines Journal of Marine Science and Engineering heave plate free surface effect floating offshore wind turbine hydrodynamic coefficients added mass damping coefficient |
| title | Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines |
| title_full | Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines |
| title_fullStr | Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines |
| title_full_unstemmed | Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines |
| title_short | Wave Induced Effects on the Hydrodynamic Coefficients of an Oscillating Heave Plate in Offshore Wind Turbines |
| title_sort | wave induced effects on the hydrodynamic coefficients of an oscillating heave plate in offshore wind turbines |
| topic | heave plate free surface effect floating offshore wind turbine hydrodynamic coefficients added mass damping coefficient |
| url | https://www.mdpi.com/2077-1312/8/8/622 |
| work_keys_str_mv | AT krishthiagarajan waveinducedeffectsonthehydrodynamiccoefficientsofanoscillatingheaveplateinoffshorewindturbines AT javiermoreno waveinducedeffectsonthehydrodynamiccoefficientsofanoscillatingheaveplateinoffshorewindturbines |