Читать книгу Wind Energy Handbook - Michael Barton Graham - Страница 93

The performance of a wind turbine can be characterised by the manner in which the three main indicators, power, torque, and thrust, vary with wind speed. The power determines the amount of energy captured by the rotor, and the torque developed determines the size of the gearbox and must be matched by whatever generator is being driven by the rotor. The rotor thrust has great influence on the structural design of the tower. It is usually convenient to express the performance by means of non‐dimensional, characteristic performance curves from which the actual performance can be determined regardless of how the turbine is operated, e.g. at constant rotational speed or some regime of variable rotor speed. Assuming that the aerodynamic performance of the rotor blades does not deteriorate, the non‐dimensional aerodynamic performance of the rotor will depend upon the tip speed ratio and, if appropriate, the pitch setting of the blades. It is usual, therefore, to display the power, torque, and thrust coefficients as functions of tip speed ratio.