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Estudo numérico da hidrodinâmica do conversor hiperbárico de energia das ondas em agitação irregular
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Orientador(es)
Resumo(s)
A exploração intensa de fontes de energia não renováveis tem tido um impacto ambiental
muito severo. A queima dos combustíveis liberta grandes quantidades de CO2 para a
atmosfera, o que contribui para o efeito de estufa provocando um aumento global da
temperatura. Neste sentido, é urgente procurar alternativas mais sustentáveis e que, ao
mesmo tempo, consigam responder à procura de energia, cada vez mais elevada. En-
tre as fontes disponíveis, a energia das ondas apresenta-se como um recurso com um
grande potencial. Em Portugal estima-se que a potência presente nas ondas varie entre 8
e 30 kW/m.
Atualmente existem diversos conceitos de dispositivos de aproveitamento de ener-
gia das ondas (WEC – wave energy converter). No entanto, devido ao facto de ainda não
existir uma tecnologia estabelecida, a percentagem de utilização destes WECs é baixa. A
divergência na escolha do tipo de WEC pode ser justificada pelas diferentes características
geográficas, de agitação ou operacionais. Do ponto de vista operacional, o conversor hiper-
bárico de energia de ondas (WEHC - wave energy hyperbaric converter) constitui uma boa
alternativa, uma vez que todo o mecanismo de extração de energia encontra-se emerso. O
WEHC pode ser facilmente integrado em estruturas costeiras e offshore existentes. Nesta
dissertação estuda-se numericamente o comportamento do WEHC em agitação irregular.
A modelação é feita usando o código numérico DualSPHysics que se baseia no método
SPH (smoothed particle hydrodynamics). Para incluir as restrições mecânicas entre corpos
rígidos é utilizada a implementação do ProjectChrono.
Todas as simulações foram realizadas com os parâmetros previamente testados por
Silva (2019) e Bernardo (2020). Na primeira fase estudou-se o WEHC sem o sistema PTO
com o objetivo de averiguar a evolução da resposta do dispositivo. Verificou-se um pico
na amplitude para frequências entre 0.15 Hz e 0.17 Hz. Também foram comparadas si-
mulações com diferentes alturas e observou-se um aumento do RAO para alturas de onda
superiores. Na segunda fase incluiu-se o sistema PTO e foi possível obter informações so-
bre a potência e rendimento do WEHC para as diferentes condições de agitação testadas.
O CWR (capture width ratio) médio foi de 15%.
The intensive exploitation of non renewable energy sources has been having a very severe environmental impact. Burning fossil fuels releases large amounts of CO2 into the atmo- sphere which contributes to the greenhouse effect, thus increasing the global temperature. Therefore, it is urgent to seek more sustainable alternatives that, at the same time, can keep up with the increasing energy demand. Among the available sources, wave energy presents itself as a resource with great potential. In Portugal it is estimated that the available wave power varies between 8 and 30 KW/m. Currently, there are several concepts for WECs (Wave Energy Converters). However, due to the fact that there’s no established technology the use percentage of these WECs is very low. The choice of WEC may differ due to different geographic, wave agitation and operational characteristics in the installation sites. Regarding operational characteristics, the WEHC (Wave Energy Hyperbaric Converter) is a good alternative because the energy extraction mechanism is completely emerged. The WEHC can be easily integrated on existing coastal and offshore structures. In this dissertation the WEHC behaviour un- der irregular waves is studied numerically. The modelation is done using the numerical tool DualSPHysics. It uses an SPH (smoothed particle hydrodynamics) method. Pro- jectChrono was used as well to include the mechanical constraints between rigid bodies. All the simulations were run with parameters previously tested by Silva (2019) and Bernardo (2020). In the first stage, the WEHC was studied without the PTO system, in order to evaluate the device’s response. It was observed a peak in amplitude between 0.15 Hz and 0.17 Hz. Simulations with different heights were also compared and it was observed an increase in the RAO parameter for higher wave heights. In the second stage, the PTO system was included and it was possible to obtain information about the absorbed power and efficiency of the device under different wave agitation conditions. The mean CWR (capture width ratio) was 15%.
The intensive exploitation of non renewable energy sources has been having a very severe environmental impact. Burning fossil fuels releases large amounts of CO2 into the atmo- sphere which contributes to the greenhouse effect, thus increasing the global temperature. Therefore, it is urgent to seek more sustainable alternatives that, at the same time, can keep up with the increasing energy demand. Among the available sources, wave energy presents itself as a resource with great potential. In Portugal it is estimated that the available wave power varies between 8 and 30 KW/m. Currently, there are several concepts for WECs (Wave Energy Converters). However, due to the fact that there’s no established technology the use percentage of these WECs is very low. The choice of WEC may differ due to different geographic, wave agitation and operational characteristics in the installation sites. Regarding operational characteristics, the WEHC (Wave Energy Hyperbaric Converter) is a good alternative because the energy extraction mechanism is completely emerged. The WEHC can be easily integrated on existing coastal and offshore structures. In this dissertation the WEHC behaviour un- der irregular waves is studied numerically. The modelation is done using the numerical tool DualSPHysics. It uses an SPH (smoothed particle hydrodynamics) method. Pro- jectChrono was used as well to include the mechanical constraints between rigid bodies. All the simulations were run with parameters previously tested by Silva (2019) and Bernardo (2020). In the first stage, the WEHC was studied without the PTO system, in order to evaluate the device’s response. It was observed a peak in amplitude between 0.15 Hz and 0.17 Hz. Simulations with different heights were also compared and it was observed an increase in the RAO parameter for higher wave heights. In the second stage, the PTO system was included and it was possible to obtain information about the absorbed power and efficiency of the device under different wave agitation conditions. The mean CWR (capture width ratio) was 15%.
Descrição
Palavras-chave
Energia das ondas conversor hiperbárico de energia das ondas (WEHC) simulação numérica smoothed particle hydrodynamics (SPH) DualSPHysics sistema PTO