A MATHEMATICAL-MODEL OF BIRD COLLISIONS WITH WIND TURBINE ROTORS

When a bird flies through the disk swept out by the blades of a wind t urbine rotor, the probability of collision depends on the motions and dimensions of the bird and the blades. The collision model in this pap er predicts the probability for birds that glide upwind, downwind, and across the wind past simple one-dimensional blades represented by str aight lines, and upwind and downwind past more realistic three-dimensi onal blades with chord and twist. Probabilities vary over the surface of the disk, and in most cases, the tip of the blade is less likely to collide with a bird than parts of the blade nearer the hub. The mean probability may be found by integration over the disk area. The collis ion model identifies the rotor characteristics that could be altered t o make turbines safer for birds.