Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different a...Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory （NREL） phase V1 wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface （AMI） method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.展开更多
In the studies of fate and transport of air emissions from animal feeding operations,Gaussian based dispersion models have been commonly used to predict downwind pollutant concentrations through forward modeling appro...In the studies of fate and transport of air emissions from animal feeding operations,Gaussian based dispersion models have been commonly used to predict downwind pollutant concentrations through forward modeling approach,or to derive emission rates and emission factors through inverse dispersion modeling approach.In the Gaussian dispersion modeling process,downwind sampling location and sampling height could generate significant impact on accuracy of the model validation,or inverse modeling results based upon field measurements.This study theoretically analyzed the impact of downwind locations and sampling height on Gaussian dispersion modeling.It was discovered that the field sampling needs to be conducted at the locations beyond the plume touching-ground distance,at a downwind distance as short as 5 m for the case scenario with zero rise of emission plume under the atmospheric stability class C,or as long as 297 m for the case scenario with 15 m rise of emission plume under the atmospheric stability class F.In order to measure the PM concentrations of the dispersion plume,the minimum sampling height at the locations within the plume touching-ground distance varied from ground level to as high as almost 14 m,whereas for the locations beyond the plume touching-ground distance,a sampling height of ground level would be acceptable.展开更多
In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blade...In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by using the coning blade of 20°.Besides,owing to the torsional deformation of very soft blade,the self-power control characteristic is observed in every test rotor regardless of coning angle in the range of 0°-20° under the wind speed less than 12 m/s.展开更多
One of the roles of nuctear regulators is to review population projections calculated by applicants for populations lying in the vicinity of nuclear power plants. This paper examines methods of calculating rates of gr...One of the roles of nuctear regulators is to review population projections calculated by applicants for populations lying in the vicinity of nuclear power plants. This paper examines methods of calculating rates of growth and thus calculating future population growth. This paper is concerned about regulators making sure that nuclear power plants are not located near densely populated centers and that population centers located near nuclear power plants do not become densely populated. In the case of El Dabaa city in the north coast of Egypt, south west of the nominated plant site, three rates of growth 1.5%, 2.5% and 3% were identified. The first is the current population growth rate of the city, the second is the average national growth rate and the third is the expected growth rate of the city when the nuclear power plant gets constructed and operated. In all three cases, this city is a population center and rules of distance from the nuclear power plant shall apply. Thus the further natural growth of this city should be controlled and directed away from the downwind of the plant.展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant Nos. 51379125, 51411130131, 11432009）, the National Key Basic Research Development Plan （973 Plan） Project of China （Grant No. 2013CB036103）, High Technology of Marine Research Project of the Ministry of Industry and Information Technology of China, ABS（China）, and the Program for Professor of Special Appointment （Eastern Scholar） at Shanghai Institutions of Higher Learning （Grant No. 2013022）.
文摘Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory （NREL） phase V1 wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface （AMI） method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.
基金supported by the NSF-CAREER Award No.CBET-0954673.
文摘In the studies of fate and transport of air emissions from animal feeding operations,Gaussian based dispersion models have been commonly used to predict downwind pollutant concentrations through forward modeling approach,or to derive emission rates and emission factors through inverse dispersion modeling approach.In the Gaussian dispersion modeling process,downwind sampling location and sampling height could generate significant impact on accuracy of the model validation,or inverse modeling results based upon field measurements.This study theoretically analyzed the impact of downwind locations and sampling height on Gaussian dispersion modeling.It was discovered that the field sampling needs to be conducted at the locations beyond the plume touching-ground distance,at a downwind distance as short as 5 m for the case scenario with zero rise of emission plume under the atmospheric stability class C,or as long as 297 m for the case scenario with 15 m rise of emission plume under the atmospheric stability class F.In order to measure the PM concentrations of the dispersion plume,the minimum sampling height at the locations within the plume touching-ground distance varied from ground level to as high as almost 14 m,whereas for the locations beyond the plume touching-ground distance,a sampling height of ground level would be acceptable.
文摘In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by using the coning blade of 20°.Besides,owing to the torsional deformation of very soft blade,the self-power control characteristic is observed in every test rotor regardless of coning angle in the range of 0°-20° under the wind speed less than 12 m/s.
文摘One of the roles of nuctear regulators is to review population projections calculated by applicants for populations lying in the vicinity of nuclear power plants. This paper examines methods of calculating rates of growth and thus calculating future population growth. This paper is concerned about regulators making sure that nuclear power plants are not located near densely populated centers and that population centers located near nuclear power plants do not become densely populated. In the case of El Dabaa city in the north coast of Egypt, south west of the nominated plant site, three rates of growth 1.5%, 2.5% and 3% were identified. The first is the current population growth rate of the city, the second is the average national growth rate and the third is the expected growth rate of the city when the nuclear power plant gets constructed and operated. In all three cases, this city is a population center and rules of distance from the nuclear power plant shall apply. Thus the further natural growth of this city should be controlled and directed away from the downwind of the plant.
