The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed...The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoil modified to be flexible at 150 from the main blade axis of the turbine at the trailing edge located about 70 % of the blade chord length using fluent solving Reynolds average Navier-strokes equation. The results obtained from DMST model and the simulation results were then compared. The result shows that the CFD simulation with airfoil modified has shown better performance at low tip speed ratios for the modeled turbine.展开更多
Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separ...Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.展开更多
Wind-driven power harvestings attract attentions since their target wind speeds are quite low less than the so-called cut-in wind speed, which is generally recognized as around 3 m/s. The extant power harvestings driv...Wind-driven power harvestings attract attentions since their target wind speeds are quite low less than the so-called cut-in wind speed, which is generally recognized as around 3 m/s. The extant power harvestings driven by wind-induced-air-column-resonations (i.e. acoustic-pressures) are still lacking simplicity, scale flexibility and solid strategies for practical applications. Therefore, the piezoelectric power harvesters via acoustic-pressures driven by low-speedwind-forces with resonating-tubes and wind-collectors were invented so as to complement all the lacks. The wind-collector as well as the resonating-tube contributed to upraise the power harvesting density. The champion power harvesting density of 19.5 nW/dm2 could be procured at 2.3 m/s of an artificial wind and the optimal resonating-tube and wind-collector. Power harvesting proofs from the natural wind with low mean speeds down to about 0.6 m/s were successfully obtained. The cut-in wind speed of the prototype piezoelectric power harvester was found to be quite low as about 0.4 m/s, signifying its ubiquity. Finally, a multi-bundle pendant-type piezoelectric power harvester was specifically presented together with professing the solid and multiple strategies for practical applications.展开更多
The performance and annual energy output have to be predicted to maximize the economic benefits from a wind turbine. Mathematically predicting the performance of Darrieus type lift based turbines are challenging due t...The performance and annual energy output have to be predicted to maximize the economic benefits from a wind turbine. Mathematically predicting the performance of Darrieus type lift based turbines are challenging due to the inconsistent angle of attack, blade wake interaction and local induced velocities giving rise to complex flow physics. A reliable and validated mathematical model is therefore essential to optimize the various design parameters prior to manufacture. The objective of the current study is to evaluate widely employed aerodynamic models based on their prediction accuracy, limitations, and computational requirements. Double multiple stream tube models have been discussed in detail and the predictions are experimentally validated through the wind tunnel test of three-bladed H-Darrieus rotor in terms of torque and power coefficient. The possible sources for the deviation between the predicted and measured values have been discussed and concluded with potential solutions.展开更多
随着新能源大规模接入电网,为应对新能源随机性和波动性给互联系统负荷频率控制(Load Frequency Control,LFC)带来的不确定问题,实现新能源电力系统多约束条件下的优化运行,建立了含风电机组的LFC多胞模型,以减少模型参数不确定对控制...随着新能源大规模接入电网,为应对新能源随机性和波动性给互联系统负荷频率控制(Load Frequency Control,LFC)带来的不确定问题,实现新能源电力系统多约束条件下的优化运行,建立了含风电机组的LFC多胞模型,以减少模型参数不确定对控制系统的影响。设计了基于原对偶神经网络(Primal-Dual Neural Network,PDNN)的Tube鲁棒模型预测控制(Tube-Robust Model Predictive Control,Tube-RMPC)策略。将标称模型预测控制器与辅助反馈控制器结合,通过PDNN实时求解标称模型预测控制器以保证为LFC系统产生最优状态轨迹。设计辅助反馈控制器抵消外部干扰,使实际系统的状态维持在以标称轨迹为中心的Tube内。最后,对含风电的三区域负荷频率控制系统进行仿真研究,结果表明所提出的Tube-RMPC控制策略,不仅能够有效提高控制精度,还能增强系统鲁棒性,提高实时优化效率。展开更多
文摘The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoil modified to be flexible at 150 from the main blade axis of the turbine at the trailing edge located about 70 % of the blade chord length using fluent solving Reynolds average Navier-strokes equation. The results obtained from DMST model and the simulation results were then compared. The result shows that the CFD simulation with airfoil modified has shown better performance at low tip speed ratios for the modeled turbine.
文摘Being aimed at the inside wall wrinkling and sinking phenomenon of palladium-yttrium alloy thin wall spiral tube used for preparation of high purity hydrogen, extraction of hydrogen isotope, and purification and separation of hydrogen in the winding process, this article analyzed the reasons for above phenomena, established a numerical simulation model of winding process of above tube, using elastic-plastic Finite Element method analyzed the max. tensile stress and max. compression stress and their locations, thereby provides a theory base for the control of working forming course of thin wall spiral tube.
文摘Wind-driven power harvestings attract attentions since their target wind speeds are quite low less than the so-called cut-in wind speed, which is generally recognized as around 3 m/s. The extant power harvestings driven by wind-induced-air-column-resonations (i.e. acoustic-pressures) are still lacking simplicity, scale flexibility and solid strategies for practical applications. Therefore, the piezoelectric power harvesters via acoustic-pressures driven by low-speedwind-forces with resonating-tubes and wind-collectors were invented so as to complement all the lacks. The wind-collector as well as the resonating-tube contributed to upraise the power harvesting density. The champion power harvesting density of 19.5 nW/dm2 could be procured at 2.3 m/s of an artificial wind and the optimal resonating-tube and wind-collector. Power harvesting proofs from the natural wind with low mean speeds down to about 0.6 m/s were successfully obtained. The cut-in wind speed of the prototype piezoelectric power harvester was found to be quite low as about 0.4 m/s, signifying its ubiquity. Finally, a multi-bundle pendant-type piezoelectric power harvester was specifically presented together with professing the solid and multiple strategies for practical applications.
文摘The performance and annual energy output have to be predicted to maximize the economic benefits from a wind turbine. Mathematically predicting the performance of Darrieus type lift based turbines are challenging due to the inconsistent angle of attack, blade wake interaction and local induced velocities giving rise to complex flow physics. A reliable and validated mathematical model is therefore essential to optimize the various design parameters prior to manufacture. The objective of the current study is to evaluate widely employed aerodynamic models based on their prediction accuracy, limitations, and computational requirements. Double multiple stream tube models have been discussed in detail and the predictions are experimentally validated through the wind tunnel test of three-bladed H-Darrieus rotor in terms of torque and power coefficient. The possible sources for the deviation between the predicted and measured values have been discussed and concluded with potential solutions.
文摘随着新能源大规模接入电网,为应对新能源随机性和波动性给互联系统负荷频率控制(Load Frequency Control,LFC)带来的不确定问题,实现新能源电力系统多约束条件下的优化运行,建立了含风电机组的LFC多胞模型,以减少模型参数不确定对控制系统的影响。设计了基于原对偶神经网络(Primal-Dual Neural Network,PDNN)的Tube鲁棒模型预测控制(Tube-Robust Model Predictive Control,Tube-RMPC)策略。将标称模型预测控制器与辅助反馈控制器结合,通过PDNN实时求解标称模型预测控制器以保证为LFC系统产生最优状态轨迹。设计辅助反馈控制器抵消外部干扰,使实际系统的状态维持在以标称轨迹为中心的Tube内。最后,对含风电的三区域负荷频率控制系统进行仿真研究,结果表明所提出的Tube-RMPC控制策略,不仅能够有效提高控制精度,还能增强系统鲁棒性,提高实时优化效率。
