How are the turbulence induced losses calculated?
Turbulence induced losses are calculated individually for each directional sector. The user selects a terrain description that best matches the site characteristics in each direction (N, NE, E, SE, S, SW, W, and NW). An assumed turbulence loss is estimated for each direction based on the user selected terrain description. Each terrain description has a corresponding surface roughness parameter. Roughness values used in the program include: • Cut grass – 0.007 m • Short-grass prairie – 0.020 m • Crops, tall-grass prairie – 0.050 m • Hedges – 0.085 m • Scattered trees and hedges – 0.150 m • Trees, hedges, a few buildings – 0.300 m • Suburbs – 0.400 m • Woodlands – 1.000 m The Small windExplorer estimates turbulence losses by calculating the estimated ambient turbulence intensity using the surface roughness and turbine hub height: Turbulence losses are weighted by the percentage of energy that is expected from each direction and then combined to compute a total turbulence loss for the sit
