In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic eff...In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic effect during its rotation at a high speed. A blade must have the maximum output and resist to aerodynamic loads distributed over its length, which are related to its geometrical characteristics and the speed of the wind. For that, the authors wrote the relations whom determine these loads according to the flow speed of the wind, then, the authors integrated them in the laws of structure mechanics to obtain the motion equations of the blade. This process was applied to a twisted blade with a length of 1.9 m, built out of pressed aluminum sheet with a profile of the type NACA; this profile gives the best aerodynamic output. This blade is an element of a three-bladed propeller for wind turbine of maximum power 5 kW. Finally, we visualized its deformations and then the authors checked its holding in service.展开更多
Photothermal deflection is widely used to study defects in materials. Both high spatial resolution and high sensitivity are required to detect them. In order to improve the theoretical model in the case of uniform hea...Photothermal deflection is widely used to study defects in materials. Both high spatial resolution and high sensitivity are required to detect them. In order to improve the theoretical model in the case of uniform heating (one dimensional heat treatment) we have chosen to heat the sample by a halogen lamp. The sample which contains a known surface and subsurface defects is first covered by a thin graphite layer and placed in air. The sample fixed on a vertical holder is able to move in the x and y directions thanks a two stepper motors. The measurement showed excellent agreement between experimental and simulation results.展开更多
文摘In this work the authors present a calculation process of the blades for wind turbine with horizontal axis. It is about a blade discretized by the finite element method （FEM） in order to determine the gyroscopic effect during its rotation at a high speed. A blade must have the maximum output and resist to aerodynamic loads distributed over its length, which are related to its geometrical characteristics and the speed of the wind. For that, the authors wrote the relations whom determine these loads according to the flow speed of the wind, then, the authors integrated them in the laws of structure mechanics to obtain the motion equations of the blade. This process was applied to a twisted blade with a length of 1.9 m, built out of pressed aluminum sheet with a profile of the type NACA; this profile gives the best aerodynamic output. This blade is an element of a three-bladed propeller for wind turbine of maximum power 5 kW. Finally, we visualized its deformations and then the authors checked its holding in service.
文摘Photothermal deflection is widely used to study defects in materials. Both high spatial resolution and high sensitivity are required to detect them. In order to improve the theoretical model in the case of uniform heating (one dimensional heat treatment) we have chosen to heat the sample by a halogen lamp. The sample which contains a known surface and subsurface defects is first covered by a thin graphite layer and placed in air. The sample fixed on a vertical holder is able to move in the x and y directions thanks a two stepper motors. The measurement showed excellent agreement between experimental and simulation results.
