The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）....The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）.Turbines using diffuser are called DWATs （Diffuser Augmented Turbines）,and have efficiency bigger than the Betz limit （maximum energy flow extracted = 59.26%）. Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement.展开更多
Brazilian biomes are home to a significant portion of the world’s biodiversity,with a total of 14%of existing species and still concentrate 20%of the world’s water resources.However,changes in biomes have a direct i...Brazilian biomes are home to a significant portion of the world’s biodiversity,with a total of 14%of existing species and still concentrate 20%of the world’s water resources.However,changes in biomes have a direct impact on rainfall patterns and water recycling.Based on this,the objective was to evaluate the variability of rainfall in the four existing biomes in the Northeast Brazil(NEB)and their interaction with the ENSO climate variability mode and regional scale meteorological systems via CHELSA product.For this,monthly rainfall data were used from 1979 to 2013,with a spatial resolution of 1 km×1 km of the CHELSA product,and seasonal and annual rainfall patterns were extracted via boxplot.It was found that the rainy season in the Amazon,Caatinga and Cerrado biomes occurred between January and April,with varying intensities,except for the Atlantic Forest.Such seasonality patterns are associated with the NEB meteorological systems,with emphasis on ITCZ(all Biomes),UTCV(Amazon,Caatinga and Cerrado),Frontal Systems(extreme south of Caatinga,Cerrado and Atlantic Forest)and EWD/TWD in the(Atlantic Forest).In the inter-annual scale,the remarkable influence of ENSO was verified,mainly in the years 1983,1985,1989,1993,1998,2009 and 2012.It is noteworthy that 1985 was the wettest year of the period,with a surplus in all biomes,while the driest year differs between the Amazon(1983),Atlantic Forest and Caatinga(1993)and Cerrado(2012)biomes.The study via orbital product in NEB showed that anthropogenic processes and natural variability interfere with the forms of rain interception in the biomes and hence in rainfall patterns and water recycling in NEB.展开更多
文摘The use of diffusers around the horizontal-axis wind turbines has been widely studied since the diffuser improves the power coefficient of the turbine and it is often called DAWTs （diffuser augmented wind turbines）.Turbines using diffuser are called DWATs （Diffuser Augmented Turbines）,and have efficiency bigger than the Betz limit （maximum energy flow extracted = 59.26%）. Thus, this study presents a mathematical model describing the behavior of the velocity profile internally to a diffuser according to the characteristics of flow and geometry of a conical diffuser. The results are compared with experimental data and show good agreement.
基金supported by the National Council for Research and Development(CNPq)[424605/2018-0]Education Personnel Improvement Coordination(CAPES)[001]National Council for Research and Development(CNPq)[304936/2015-4].
文摘Brazilian biomes are home to a significant portion of the world’s biodiversity,with a total of 14%of existing species and still concentrate 20%of the world’s water resources.However,changes in biomes have a direct impact on rainfall patterns and water recycling.Based on this,the objective was to evaluate the variability of rainfall in the four existing biomes in the Northeast Brazil(NEB)and their interaction with the ENSO climate variability mode and regional scale meteorological systems via CHELSA product.For this,monthly rainfall data were used from 1979 to 2013,with a spatial resolution of 1 km×1 km of the CHELSA product,and seasonal and annual rainfall patterns were extracted via boxplot.It was found that the rainy season in the Amazon,Caatinga and Cerrado biomes occurred between January and April,with varying intensities,except for the Atlantic Forest.Such seasonality patterns are associated with the NEB meteorological systems,with emphasis on ITCZ(all Biomes),UTCV(Amazon,Caatinga and Cerrado),Frontal Systems(extreme south of Caatinga,Cerrado and Atlantic Forest)and EWD/TWD in the(Atlantic Forest).In the inter-annual scale,the remarkable influence of ENSO was verified,mainly in the years 1983,1985,1989,1993,1998,2009 and 2012.It is noteworthy that 1985 was the wettest year of the period,with a surplus in all biomes,while the driest year differs between the Amazon(1983),Atlantic Forest and Caatinga(1993)and Cerrado(2012)biomes.The study via orbital product in NEB showed that anthropogenic processes and natural variability interfere with the forms of rain interception in the biomes and hence in rainfall patterns and water recycling in NEB.
