The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which compris...The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which comprises an aerodynamic part to calculate the aerodynamic loads and a structural part to determine the structural dynamic responses, is established to describe the classical flutter of the blades. For the aerodynamic part, Theodorsen unsteady aerodynamics model is used. For the structural part, Lagrange’s equation is employed. The flutter speed is determined by introducing “V–g” method to the aeroelastic model, which converts the issue of classical flutter speed determination into an eigenvalue problem. Furthermore, the time domain aeroelastic response of the wind turbine blade section is obtained with employing Runge-Kutta method. The results show that four cases （i.e., reducing the blade torsional stiffness, moving the center of gravity or the elastic axis towards the trailing edge of the section, and placing the turbine in high air density area） will decrease the flutter speed. Therefore, the judicious selection of the four parameters （the torsional stiffness, the chordwise position of the center of gravity, the elastic axis position and air density） can increase the relative inflow speed at the blade section associated with the onset of flutter.展开更多
Methanol-reforming hydrogen production fuel cell(MRFC)systems demonstrate significant advantages in storage safety,energy density,and adaptability for distributed power generation and propulsion applications.However,e...Methanol-reforming hydrogen production fuel cell(MRFC)systems demonstrate significant advantages in storage safety,energy density,and adaptability for distributed power generation and propulsion applications.However,existing systems below 30 kW face considerable limitations in dynamic response and power output capacity,while current research lacks comprehensive dynamic simulation methodologies and parameter optimization strategies for 100-kW-class implementations.This study establishes a 200-kW MRFC system model with several key innovations:An Integrated Thermodynamic-Kinetic Framework developed in Aspen Plus®couples essential modules(reformer,membrane separation with 65%-95%H₂purification efficiency,and proton exchange membrane fuel cells(PEMFC)stack)to address technical challenges in large-scale system design.Global Sensitivity Analysis quantifies the impact of critical operating parameters—steam-to-methanol ratio(S/C=1.0-1.5),catalytic conversion efficiency(80%-95%),and purification efficiency(65%-95%)—revealing purification efficiency contributes 59.1%to overall system efficiency.The Dynamic Optimization Strategy,based on energy hub theory,resolves the coupling mechanism between efficiency and stability during load transitions,achieving 50%-100%load changes within 188 s(validated against 5 kW experimental data with<3%deviation).The system's rated efficiency improved from 41.0%to 45.4%postoptimization,exceeding typical small-scale systems(<40%).This research provides a scalable 1D dynamic simulation method that reduces extrapolation errors from>15%to<3%compared to conventional small-scale models,while implementing a hierarchical parameter sensitivity strategy that reduces system tuning cycles by 40%,offering valuable theoretical guidance for industrialscale system design.展开更多
基金Project(2015B37714)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(51605005)supported by the National Natural Science Foundation of China+1 种基金Project(ZK16-03-03)supported by the Open Foundation of Jiangsu Wind Technology Center,ChinaProject([2013]56)supported by the First Group of 2011 Plan of Jiangsu Province,China
文摘The parameter sensitivities affecting the flutter speed of the NREL （National Renewable Energy Laboratory） 5-MW baseline HAWT （horizontal axis wind turbine） blades are analyzed. An aeroelastic model, which comprises an aerodynamic part to calculate the aerodynamic loads and a structural part to determine the structural dynamic responses, is established to describe the classical flutter of the blades. For the aerodynamic part, Theodorsen unsteady aerodynamics model is used. For the structural part, Lagrange’s equation is employed. The flutter speed is determined by introducing “V–g” method to the aeroelastic model, which converts the issue of classical flutter speed determination into an eigenvalue problem. Furthermore, the time domain aeroelastic response of the wind turbine blade section is obtained with employing Runge-Kutta method. The results show that four cases （i.e., reducing the blade torsional stiffness, moving the center of gravity or the elastic axis towards the trailing edge of the section, and placing the turbine in high air density area） will decrease the flutter speed. Therefore, the judicious selection of the four parameters （the torsional stiffness, the chordwise position of the center of gravity, the elastic axis position and air density） can increase the relative inflow speed at the blade section associated with the onset of flutter.
文摘Methanol-reforming hydrogen production fuel cell(MRFC)systems demonstrate significant advantages in storage safety,energy density,and adaptability for distributed power generation and propulsion applications.However,existing systems below 30 kW face considerable limitations in dynamic response and power output capacity,while current research lacks comprehensive dynamic simulation methodologies and parameter optimization strategies for 100-kW-class implementations.This study establishes a 200-kW MRFC system model with several key innovations:An Integrated Thermodynamic-Kinetic Framework developed in Aspen Plus®couples essential modules(reformer,membrane separation with 65%-95%H₂purification efficiency,and proton exchange membrane fuel cells(PEMFC)stack)to address technical challenges in large-scale system design.Global Sensitivity Analysis quantifies the impact of critical operating parameters—steam-to-methanol ratio(S/C=1.0-1.5),catalytic conversion efficiency(80%-95%),and purification efficiency(65%-95%)—revealing purification efficiency contributes 59.1%to overall system efficiency.The Dynamic Optimization Strategy,based on energy hub theory,resolves the coupling mechanism between efficiency and stability during load transitions,achieving 50%-100%load changes within 188 s(validated against 5 kW experimental data with<3%deviation).The system's rated efficiency improved from 41.0%to 45.4%postoptimization,exceeding typical small-scale systems(<40%).This research provides a scalable 1D dynamic simulation method that reduces extrapolation errors from>15%to<3%compared to conventional small-scale models,while implementing a hierarchical parameter sensitivity strategy that reduces system tuning cycles by 40%,offering valuable theoretical guidance for industrialscale system design.
