Analysis of turbulence intensity in the megacity of Beijing by High-frequency observations on a 325-m Tower

Abstract

Turbulent flow over complex urban morphology poses challenges to utilization of distributed wind energy in cities. In this paper, turbulence intensity (TI), which is often used to guide wind turbine design and evaluate wind power production, is analyzed by high-frequency observations on a 325-m tower located in the downtown of Beijing, China. The results show that the characteristics of TI, including the diurnal variation, the statistical distribution, and the relations between TI and wind speeds near the ground are significantly different from these at higher heights. It is also found that the normal turbulence model (NTM) with the parameters recommended by the IEC standard cannot fit the data well. The new NTM parameters are given by the least-square fittings. Besides, a three-parameter model is found to fit the data well and performs slightly better than the NTM with the least-square fitting parameters. This research indicates that the NTM parameters in the IEC standard should be re-evaluated in urban areas, and different turbulence model parameters are recommended for higher and lower hub heights.