With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cau...With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cause excessive vibration of the WTT.To investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this study.First,a mathematical model is established based on structural dynamics under seismic excitation.Then,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning optimization.Next,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal acceleration.Finally,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the PTMD.In addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.展开更多
The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfo...The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfort.In this study,the effect of ventilation realized using a wind tower on the thermal quality of a classroom was investigated.In the study,two popular models(unidirectional and multidirectional wind tower)were studied,and the model that provided more ergonomic ventilation to sitting users based on climate conditions of the province of Trabzon(Turkey)during the month of August was determined.The more efficient model was studied further.Some dimensional changes in width,height,and shelf height were applied to it to find a model that provided more comfort for the used thermal conditions.The models were modelled and simulated using ANSYS FLUENT.Velocity distributions were generated to ease the interpretation of the results.With the calculated average wind speeds in different regions in the classroom,the thermal sensation in the space was evaluated.Furthermore,the thermal perception of users of the retained model was evaluated by entering thermal comfort parameter values calculated for the relevant region into the CBE thermal comfort tool available online.The change in the dimensional features of the wind tower had an impact on wind tower performance.Ventilation provided by wind towers under the thermal conditions of Trabzon in August often caused thermal discomfort.展开更多
A theoretical model is developed to establish an indepth understanding of the performance of a three-stage wind tower with a bypass system for indoor cooling in rural dry and hot climates. Model simulations are presen...A theoretical model is developed to establish an indepth understanding of the performance of a three-stage wind tower with a bypass system for indoor cooling in rural dry and hot climates. Model simulations are presented for a wide range of ambient conditions that include inlet wind speed, inlet temperature and relative humidity. Simulation results provide an insight into the desirable water flow rates and air-to-water loadings for comfort zone tem-peratures and relative humidity levels at the exit of the wind tower. Simulations show wind towers with variable cross-sections provide an increase in the cooling power for the same inlet wind speed, inlet air temperature and relative humidity when compared to wind towers with a constant cross-section. The study shall lead to a better understanding to designing wind towers that are both environmentally friendly and energy efficient.展开更多
Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In t...Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In this study,the use of funnels at the openings of wind towers for wind ingress and egress is proposed primarily to increase the mass flow captured by the wind tower.The use of funnels in the wind in gress openings in creases the inlet area,improving the capture of wind.In parallel,the use of funnels in the egress openings modifies the wake of the tower,which aims to ease the exit of the flow from inside the building.Several design configurations are presented,where the length and width of the funnels are changed and tested separately by computational fluid dynamics(CFD).Results of over 120 CFD simulations are presented and compared.The volumetric flow entering the wind towers in creases by 10.7% in several cases.These results in dicate that adding funnels to wind towers could positively in fluence their performance.Changing the dimensions of the funnels affects their efficacy and can increase or decrease the airflow entering the tower.展开更多
The wind energy industry has been growing rapidly during the past decades.Along with this growth,engineering problems have gradually emerged in the wind power industry,including those related to the structural reliabi...The wind energy industry has been growing rapidly during the past decades.Along with this growth,engineering problems have gradually emerged in the wind power industry,including those related to the structural reliability of turbine towers.This study proposes a rapid seismic analysis methodology for existing wind turbine tower structures.The method is demonstrated and validated using a case study on a 1.5 MW tubular steel wind turbine tower.Three finite element(FE)models are developed first.Field tests are conducted to obtain the turbine tower’s vibrational characteristics.The tests include(1) remotely measuring the tower vibration frequencies using a long range laser Doppler Vibrometer and(2) monitoring the tower structural vibration by mounting accelerometers along the height of the tubular structure.In-situ measurements are used to validate and update the FE models of the wind turbine tower.With the updated FE model that represents the practical structural conditions,seismic analyses are performed to study the structural failure,which is defined by the steel yielding of the tubular tower.This research is anticipated to benefit the management of the increasing number of wind energy converters by providing an understanding of the seismic assessment of existing tubular steel wind turbine towers.展开更多
Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external l...Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.展开更多
Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive equipments.In this work,a tapered beam model is proposed ...Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive equipments.In this work,a tapered beam model is proposed to investigate the dynamic response of an offshore wind turbine tower on the monopile foundation assembled with rotating blades in the complex ocean environment.Several environment factors like wind,wave,current,and soil resistance are taken into account.The proposed model is ana-lytically solved with the Galerkin method.Based on the numerical results,the effects of various structure parameters including the taper angle,the height and thickness of the tower,the depth,and the diameter and the cement filler of the monopile on the funda-mental natural frequency of the wind turbine tower system are investigated in detail.It is found that the fundamental natural frequency decreases with the increase in the taper angle and the height and thickness of the tower,and increases with the increase in the diameter of the monopile.Moreover,filling cement into the monopile can effectively im-prove the fundamental natural frequency of the wind turbine tower system,but there is a critical value of the amount of cement maximizing the property of the monopile.This research may be helpful in the design and safety evaluation of offshore wind turbines.展开更多
A multi-objective optimization process for wind turbine steel towers is described in present work.The objective functions are tower top deformation and mass.The tower's height,radius and thickness are considered a...A multi-objective optimization process for wind turbine steel towers is described in present work.The objective functions are tower top deformation and mass.The tower's height,radius and thickness are considered as design variables.The mathematical relationships between objective functions and variables were predicted by adopting a response surface methodology(RSM).Furthermore,the multi-objective non-dominated sorting genetic algorithm-II(NSGA-II)is adopted to optimize the tower structure to achieve accurate results with the minimum top deformation and total mass.A case study on a 2MW wind turbine tower optimization is given,which computes the desired tower structure parameters.The results are compared with the original tower:a reduction of tower top deformation reduction by about 16.5%and a reduction of a mass by about 1.5%could be achieved for such an optimization process.展开更多
The 2MW wind turbine tower is considered as the baseline configuration for structural optimization.The design variables consist of the thickness and height located at the top tower junction.The relationships between t...The 2MW wind turbine tower is considered as the baseline configuration for structural optimization.The design variables consist of the thickness and height located at the top tower junction.The relationships between the design variables and the optimization objectives(mass,equivalent stress,top displacement and fatigue life)are mapped on the basis of uniform design and regression analysis.Subsequently,five solutions are developed by an algorithm,NSGA-III.According to their efficiency and applicability,the most suitable solution is found.This approach yields a decrease of 0.48%in the mass,a decrease of 54.48%in the equivalent stress and an increase of 8.14%in fatigue life,as compared with existing tower designs.An improved wind turbine tower is obtained for this practice.展开更多
This work takes the bionic bamboo tower(BBT)of 2 MW wind turbine as the target,and the nondominated sorting genetic algorithm(NSGA-II)is utilized to optimize its structural parameters.Specifically,the objective functi...This work takes the bionic bamboo tower(BBT)of 2 MW wind turbine as the target,and the nondominated sorting genetic algorithm(NSGA-II)is utilized to optimize its structural parameters.Specifically,the objective functions are deformation and mass.Based on the correlation analysis,the target optimization parameters were determined.Furthermore,the Kriging model of the BBT was established through the Latin Hypercube SamplingDesign(LHSD).Finally,the BBT structure is optimized withmultiple objectives under the constraints of strength,natural frequency,and size.The comparison shows that the optimized BBT has an advantage in the Design Load Case(DLC).This advantage is reflected in the fact that the overall stability of the BBT has increased by 2.45%,while the displacement of the BBT has decreased by 0.77%.In addition,the mass of the tower is decreased by 1.49%.Correspondingly,the steel consumption of each BBT will be reduced by 2789 Kg.This work provides a scientific basis for the structural design of the tower in service.展开更多
Wind turbine technology is well known around the globe as an eco-friendly and eff ective renewable power source. However, this technology often faces reliability problems due to structural vibration. This study propos...Wind turbine technology is well known around the globe as an eco-friendly and eff ective renewable power source. However, this technology often faces reliability problems due to structural vibration. This study proposes a smart semi-active vibration control system using Magnetorheological (MR) dampers where feedback controllers are optimized with nature-inspired algorithms. Proportional integral derivative (PID) and Proportional integral (PI) controllers are designed to achieve the optimal desired force and current input for MR the damper. PID control parameters are optimized using an Ant colony optimization (ACO) algorithm. The eff ectiveness of the ACO algorithm is validated by comparing its performance with Ziegler-Nichols (Z-N) and particle swarm optimization (PSO). The placement of the MR damper on the tower is also investigated to ensure structural balance and optimal desired force from the MR damper. The simulation results show that the proposed semi-active PID-ACO control strategy can signifi cantly reduce vibration on the wind turbine tower under diff erent frequencies (i.e., 67%, 73%, 79% and 34.4% at 2 Hz, 3 Hz, 4.6 Hz and 6 Hz, respectively) and amplitudes (i.e. 50%, 58% and 67% for 50 N, 80 N, and 100 N, respectively). In this study, the simulation model is validated with an experimental study in terms of natural frequency, mode shape and uncontrolled response at the 1st mode. The proposed PID-ACO control strategy and optimal MR damper position is also implemented on a lab-scaled wind turbine tower model. The results show that the vibration reduction rate is 66% and 73% in the experimental and simulation study, respectively, at the 1st mode.展开更多
In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limita...In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.展开更多
In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized ...In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized force spectrum （GFS） model of the transmission tower is deduced; （2） an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and （3） a new approach, applying load with displacement （ALD） instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads （ESWLs）. Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.展开更多
The purpose of this study is to optimize the mass of 1.5 MW wind turbine steel tower performing Genetic Algorithm method (GA). In accordance with ASCE 7-98, AISC-89 and IEC61400-1 , the impact of loads on tower is cal...The purpose of this study is to optimize the mass of 1.5 MW wind turbine steel tower performing Genetic Algorithm method (GA). In accordance with ASCE 7-98, AISC-89 and IEC61400-1 , the impact of loads on tower is calculated within the highest safety conditions against buckling strength of each sections of tower by means of GA codes. The stifness along tower is ensured entirely while the mass of tower is mitigated and optimized.展开更多
The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively l...The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively low cost. However, the energy output tends to be low for its physical size compared with other renewable energy production systems. The technical and scientific improvement of these types of generation systems has lost its momentum since the shutdown of the wellknown Spanish pilot plant “Manzanares Solar Chimney” in 1989, although it still has the potential to play a role in renewable energy in the future. We have focused on the tower component of the system to seek possible enhancements of the power output of the internal turbine. As a result of our fluid dynamic shape optimization, a diffuser-shaped tower was employed to increase the internal flow speed of a scaled model. The results show a remarkable improvement in the power output of the internal wind turbine.展开更多
To study the wind vibration response of power transmission tower, the lead viscoelastic dampers （LVDs） were applied to a cup tower. With time history analysis method, the displacement, velocity, acceleration and for...To study the wind vibration response of power transmission tower, the lead viscoelastic dampers （LVDs） were applied to a cup tower. With time history analysis method, the displacement, velocity, acceleration and force response of the tower was calculated and analyzed. The results show that the control effect of lead viscoelastic dampers is very good, and the damping ratio can reach 20% or more when they are applied to the tower head.展开更多
In the construction of wind power tower, the loading and unloading operation of tower is basically involved. However, due to the large size of wind power tower and its great characteristics in weight, it is necessary ...In the construction of wind power tower, the loading and unloading operation of tower is basically involved. However, due to the large size of wind power tower and its great characteristics in weight, it is necessary to use two gantry cranes to handle the tower crane at the same time, so as to effectively meet the transportation and handling of loading and unloading vehicles. However, in the actual construction, it is often affected by the heavy operation of the equipment. Therefore, based on this situation, this paper studies the hydraulic lifting device for wind power tower loading and unloading vehicle, in order to ensure that the device can play its due role in operation.展开更多
The manufacturing of wind power tower requires the use of complex welding technology to complete the assembly of various components, of which the application of submerged arc welding technology is very important. Tech...The manufacturing of wind power tower requires the use of complex welding technology to complete the assembly of various components, of which the application of submerged arc welding technology is very important. Technicians should ensure the quality of operation, confirm the reasonableness of welding methods, and select appropriate welding equipment and welding process. Technicians should strictly follow the welding process to complete each link, so as to control the welding quality in the production of wind power tower. In this paper, the application status and basic characteristics of the submerged arc welding technology applied in the production of wind power towers are analyzed, the preconditions for the application of the submerged arc welding technology are confirmed, and the specific application and method selection of the submerged arc welding in the production of wind power towers are studied, aiming at clarifying each technical link and process of the submerged arc welding and providing effective guidance for the operation of technicians.展开更多
The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370...The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370. http://dx.doi.org/10.4236/epe.2014.611031) was published in October, 2014.The author wishes to correct the following error in text and Figures 9-11.展开更多
基金Fundamental Research Funds for the National Natural Science Foundation of China under Grant No.52078084the Natural Science Foundation of Chongqing (cstc2021jcyj-msxmX0623)+2 种基金the 111 project of the Ministry of Educationthe Bureau of Foreign Experts of China under Grant No.B18062China Postdoctoral Science Foundation under Grant No.2021M690838。
文摘With the rapid development of large megawatt wind turbines,the operation environment of wind turbine towers(WTTs)has become increasingly complex.In particular,seismic excitation can create a resonance response and cause excessive vibration of the WTT.To investigate the vibration attenuation performance of the WTT under seismic excitations,a novel passive vibration control device,called a prestressed tuned mass damper(PS-TMD),is presented in this study.First,a mathematical model is established based on structural dynamics under seismic excitation.Then,the mathematical analytical expression of the dynamic coefficient is deduced,and the parameter design method is obtained by system tuning optimization.Next,based on a theoretical analysis and parameter design,the numerical results showed that the PS-TMD was able to effectively mitigate the resonance under the harmonic basal acceleration.Finally,the time-history analysis method is used to verify the effectiveness of the traditional pendulum tuned mass damper(PTMD)and the novel PS-TMD device,and the results indicate that the vibration attenuation performance of the PS-TMD is better than the PTMD.In addition,the PS-TMD avoids the nonlinear effect due to the large oscillation angle,and has the potential to dissipate hysteretic energy under seismic excitation.
文摘The spaces must be designed in accordance with certain design principles for people to feel comfortable.In accordance with that,building ventilation is particularly important during hot periods to ensure thermal comfort.In this study,the effect of ventilation realized using a wind tower on the thermal quality of a classroom was investigated.In the study,two popular models(unidirectional and multidirectional wind tower)were studied,and the model that provided more ergonomic ventilation to sitting users based on climate conditions of the province of Trabzon(Turkey)during the month of August was determined.The more efficient model was studied further.Some dimensional changes in width,height,and shelf height were applied to it to find a model that provided more comfort for the used thermal conditions.The models were modelled and simulated using ANSYS FLUENT.Velocity distributions were generated to ease the interpretation of the results.With the calculated average wind speeds in different regions in the classroom,the thermal sensation in the space was evaluated.Furthermore,the thermal perception of users of the retained model was evaluated by entering thermal comfort parameter values calculated for the relevant region into the CBE thermal comfort tool available online.The change in the dimensional features of the wind tower had an impact on wind tower performance.Ventilation provided by wind towers under the thermal conditions of Trabzon in August often caused thermal discomfort.
文摘A theoretical model is developed to establish an indepth understanding of the performance of a three-stage wind tower with a bypass system for indoor cooling in rural dry and hot climates. Model simulations are presented for a wide range of ambient conditions that include inlet wind speed, inlet temperature and relative humidity. Simulation results provide an insight into the desirable water flow rates and air-to-water loadings for comfort zone tem-peratures and relative humidity levels at the exit of the wind tower. Simulations show wind towers with variable cross-sections provide an increase in the cooling power for the same inlet wind speed, inlet air temperature and relative humidity when compared to wind towers with a constant cross-section. The study shall lead to a better understanding to designing wind towers that are both environmentally friendly and energy efficient.
文摘Finding ways to cool buildings by natural,passive techniques is crucial in the context of global warming.For centuries,wind towers(traditi onal win dcatchers)have been used in the Middle East for cooling purposes.In this study,the use of funnels at the openings of wind towers for wind ingress and egress is proposed primarily to increase the mass flow captured by the wind tower.The use of funnels in the wind in gress openings in creases the inlet area,improving the capture of wind.In parallel,the use of funnels in the egress openings modifies the wake of the tower,which aims to ease the exit of the flow from inside the building.Several design configurations are presented,where the length and width of the funnels are changed and tested separately by computational fluid dynamics(CFD).Results of over 120 CFD simulations are presented and compared.The volumetric flow entering the wind towers in creases by 10.7% in several cases.These results in dicate that adding funnels to wind towers could positively in fluence their performance.Changing the dimensions of the funnels affects their efficacy and can increase or decrease the airflow entering the tower.
基金National Natural Science Foundation of China under Grant No.51208382Shanghai Science Foundation under Grant No.12ZR1433500+4 种基金Shanghai Pujiang Scholar Program under Grant No.13PJ1407900Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20120072120001State Key Laboratory of Power Transmission Equipment&System Security and New Technology under Grant No.2007DA10512711414State Key Laboratory of Disaster Reduction in Civil Engineering under Grant No.SLDRCE14-B-02Tongji University Testing Facility Funding under Grant No.2012096
文摘The wind energy industry has been growing rapidly during the past decades.Along with this growth,engineering problems have gradually emerged in the wind power industry,including those related to the structural reliability of turbine towers.This study proposes a rapid seismic analysis methodology for existing wind turbine tower structures.The method is demonstrated and validated using a case study on a 1.5 MW tubular steel wind turbine tower.Three finite element(FE)models are developed first.Field tests are conducted to obtain the turbine tower’s vibrational characteristics.The tests include(1) remotely measuring the tower vibration frequencies using a long range laser Doppler Vibrometer and(2) monitoring the tower structural vibration by mounting accelerometers along the height of the tubular structure.In-situ measurements are used to validate and update the FE models of the wind turbine tower.With the updated FE model that represents the practical structural conditions,seismic analyses are performed to study the structural failure,which is defined by the steel yielding of the tubular tower.This research is anticipated to benefit the management of the increasing number of wind energy converters by providing an understanding of the seismic assessment of existing tubular steel wind turbine towers.
基金the Special Research Fund for the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2019MS05070)。
文摘Flange joint part is the weak link of wind turbine tower.In view of the special structure,complex stress and easy failure of the connecting bolt of the wind turbine tower flange,the relationship between the external load of the tower section and the internal stress of the bolt is established by the finite element method,and the time series internal stress of the bolt is calculated by the Schmidt-Neuper algorithm.The S-N curve which is suitable for the connecting bolt material of the tower flange is selected by the GL2010 specification.On the basis of Miner’s fatigue cumulative damage theory and rain flow counting method,the fatigue strength of the whole ring bolt is roughly calculated,and the most dangerous part is determined.The axial symmetry model of screw connection is used for accurately calculating the fatigue cumulative damage of the bolt at the dangerous part.The results show that the fatigue life of the bolts in the most dangerous position can meet the requirements,the engineering algorithm has advantages in determining the dangerous part of the whole ring bolt,and the finite element method has high accuracy in predicting the fatigue life of the bolts in the dangerous part.The proposed method is feasible and effective in predicting the fatigue life of the flange joint bolts of the tower.
基金Project supported by the National Natural Science Foundation of China(Nos.11872233,11727804,and 11472163)the National Key Basic Research Project of China(No.2014CB046203)the Innovation Program of Shanghai Municipal Education Commission(No.2017-01-07-00-09-E00019)。
文摘Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive equipments.In this work,a tapered beam model is proposed to investigate the dynamic response of an offshore wind turbine tower on the monopile foundation assembled with rotating blades in the complex ocean environment.Several environment factors like wind,wave,current,and soil resistance are taken into account.The proposed model is ana-lytically solved with the Galerkin method.Based on the numerical results,the effects of various structure parameters including the taper angle,the height and thickness of the tower,the depth,and the diameter and the cement filler of the monopile on the funda-mental natural frequency of the wind turbine tower system are investigated in detail.It is found that the fundamental natural frequency decreases with the increase in the taper angle and the height and thickness of the tower,and increases with the increase in the diameter of the monopile.Moreover,filling cement into the monopile can effectively im-prove the fundamental natural frequency of the wind turbine tower system,but there is a critical value of the amount of cement maximizing the property of the monopile.This research may be helpful in the design and safety evaluation of offshore wind turbines.
基金Supported by the National Natural Science Foundation of China(51965034)Foudamental Research Funds for the Lanzhou City Innovation and Entrepreneurship Projct(2018-RC-25)。
文摘A multi-objective optimization process for wind turbine steel towers is described in present work.The objective functions are tower top deformation and mass.The tower's height,radius and thickness are considered as design variables.The mathematical relationships between objective functions and variables were predicted by adopting a response surface methodology(RSM).Furthermore,the multi-objective non-dominated sorting genetic algorithm-II(NSGA-II)is adopted to optimize the tower structure to achieve accurate results with the minimum top deformation and total mass.A case study on a 2MW wind turbine tower optimization is given,which computes the desired tower structure parameters.The results are compared with the original tower:a reduction of tower top deformation reduction by about 16.5%and a reduction of a mass by about 1.5%could be achieved for such an optimization process.
基金the National Natural Science Founda-tion of China(Nos.51965034 and 51565028)LanzhouTalent Innovation and Entrepreneurship Project(No.2018-RC-25)。
文摘The 2MW wind turbine tower is considered as the baseline configuration for structural optimization.The design variables consist of the thickness and height located at the top tower junction.The relationships between the design variables and the optimization objectives(mass,equivalent stress,top displacement and fatigue life)are mapped on the basis of uniform design and regression analysis.Subsequently,five solutions are developed by an algorithm,NSGA-III.According to their efficiency and applicability,the most suitable solution is found.This approach yields a decrease of 0.48%in the mass,a decrease of 54.48%in the equivalent stress and an increase of 8.14%in fatigue life,as compared with existing tower designs.An improved wind turbine tower is obtained for this practice.
基金This work was supported by the National Natural Science Foundation of China(No.51965034).
文摘This work takes the bionic bamboo tower(BBT)of 2 MW wind turbine as the target,and the nondominated sorting genetic algorithm(NSGA-II)is utilized to optimize its structural parameters.Specifically,the objective functions are deformation and mass.Based on the correlation analysis,the target optimization parameters were determined.Furthermore,the Kriging model of the BBT was established through the Latin Hypercube SamplingDesign(LHSD).Finally,the BBT structure is optimized withmultiple objectives under the constraints of strength,natural frequency,and size.The comparison shows that the optimized BBT has an advantage in the Design Load Case(DLC).This advantage is reflected in the fact that the overall stability of the BBT has increased by 2.45%,while the displacement of the BBT has decreased by 0.77%.In addition,the mass of the tower is decreased by 1.49%.Correspondingly,the steel consumption of each BBT will be reduced by 2789 Kg.This work provides a scientific basis for the structural design of the tower in service.
基金University of Malaya Research under Grant No.RP013B-15SUS,Postgraduate Research Fund(PG098-2015A)
文摘Wind turbine technology is well known around the globe as an eco-friendly and eff ective renewable power source. However, this technology often faces reliability problems due to structural vibration. This study proposes a smart semi-active vibration control system using Magnetorheological (MR) dampers where feedback controllers are optimized with nature-inspired algorithms. Proportional integral derivative (PID) and Proportional integral (PI) controllers are designed to achieve the optimal desired force and current input for MR the damper. PID control parameters are optimized using an Ant colony optimization (ACO) algorithm. The eff ectiveness of the ACO algorithm is validated by comparing its performance with Ziegler-Nichols (Z-N) and particle swarm optimization (PSO). The placement of the MR damper on the tower is also investigated to ensure structural balance and optimal desired force from the MR damper. The simulation results show that the proposed semi-active PID-ACO control strategy can signifi cantly reduce vibration on the wind turbine tower under diff erent frequencies (i.e., 67%, 73%, 79% and 34.4% at 2 Hz, 3 Hz, 4.6 Hz and 6 Hz, respectively) and amplitudes (i.e. 50%, 58% and 67% for 50 N, 80 N, and 100 N, respectively). In this study, the simulation model is validated with an experimental study in terms of natural frequency, mode shape and uncontrolled response at the 1st mode. The proposed PID-ACO control strategy and optimal MR damper position is also implemented on a lab-scaled wind turbine tower model. The results show that the vibration reduction rate is 66% and 73% in the experimental and simulation study, respectively, at the 1st mode.
基金Area Strategic Development Program inStructural Control and Intelligent Building from The HongKong Polytechnic University, and National Natural SciencFoundation of China Under Grant No. 50408011
文摘In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.
基金National Natural Science Foundation of China Under Grant No.50638010Foundation of Ministry of Education for Innovation Group Under Grant No. IRT0518
文摘In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed： （1） a higher mode generalized force spectrum （GFS） model of the transmission tower is deduced; （2） an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and （3） a new approach, applying load with displacement （ALD） instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads （ESWLs）. Finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.
文摘The purpose of this study is to optimize the mass of 1.5 MW wind turbine steel tower performing Genetic Algorithm method (GA). In accordance with ASCE 7-98, AISC-89 and IEC61400-1 , the impact of loads on tower is calculated within the highest safety conditions against buckling strength of each sections of tower by means of GA codes. The stifness along tower is ensured entirely while the mass of tower is mitigated and optimized.
文摘The purpose of this study is to improve the efficiency of the power generation system of a solar tower using fluid dynamics. The power generation system of a solar tower can be designed and constructed at relatively low cost. However, the energy output tends to be low for its physical size compared with other renewable energy production systems. The technical and scientific improvement of these types of generation systems has lost its momentum since the shutdown of the wellknown Spanish pilot plant “Manzanares Solar Chimney” in 1989, although it still has the potential to play a role in renewable energy in the future. We have focused on the tower component of the system to seek possible enhancements of the power output of the internal turbine. As a result of our fluid dynamic shape optimization, a diffuser-shaped tower was employed to increase the internal flow speed of a scaled model. The results show a remarkable improvement in the power output of the internal wind turbine.
基金Research Fund of Chinese State Grid Company (No.SGKJ[2007]413)
文摘To study the wind vibration response of power transmission tower, the lead viscoelastic dampers （LVDs） were applied to a cup tower. With time history analysis method, the displacement, velocity, acceleration and force response of the tower was calculated and analyzed. The results show that the control effect of lead viscoelastic dampers is very good, and the damping ratio can reach 20% or more when they are applied to the tower head.
文摘In the construction of wind power tower, the loading and unloading operation of tower is basically involved. However, due to the large size of wind power tower and its great characteristics in weight, it is necessary to use two gantry cranes to handle the tower crane at the same time, so as to effectively meet the transportation and handling of loading and unloading vehicles. However, in the actual construction, it is often affected by the heavy operation of the equipment. Therefore, based on this situation, this paper studies the hydraulic lifting device for wind power tower loading and unloading vehicle, in order to ensure that the device can play its due role in operation.
文摘The manufacturing of wind power tower requires the use of complex welding technology to complete the assembly of various components, of which the application of submerged arc welding technology is very important. Technicians should ensure the quality of operation, confirm the reasonableness of welding methods, and select appropriate welding equipment and welding process. Technicians should strictly follow the welding process to complete each link, so as to control the welding quality in the production of wind power tower. In this paper, the application status and basic characteristics of the submerged arc welding technology applied in the production of wind power towers are analyzed, the preconditions for the application of the submerged arc welding technology are confirmed, and the specific application and method selection of the submerged arc welding in the production of wind power towers are studied, aiming at clarifying each technical link and process of the submerged arc welding and providing effective guidance for the operation of technicians.
文摘The original online version of this article (Masataka Motoyama, Kenichiro Sugitani, Yuji Ohya, et al. (2014) “Improving the Power Generation Performance of a Solar Tower Using Thermal Updraft Wind”, 2014, 6, 362-370. http://dx.doi.org/10.4236/epe.2014.611031) was published in October, 2014.The author wishes to correct the following error in text and Figures 9-11.
