The assessment of wind speed distortions in a simulated flow around a lattice cellular communication mast

The paper investigates the problem of wind speed measurements typically encountered during the preparation phase of wind power plant projects. The study considers the case of a lattice cellular communication mast that is used for placing wind measurement sensors. In order to access the degree of distortions caused by the mast structure on the wind speed measurement results, the study uses Computational Fluid Dynamics (CFD) method. Calculations are performed for masts with different side widths and for a range of wind speeds - 1.0, 5.0, 10.0 and 15.0 m/s. The calculation results for simulated wind flows around a lattice mast are presented in the form of wind speed distortion contour maps. The analysis takes into account and discusses the implications of the requirement of the international wind measurement standard IEC 61400-12-1. The results of the analysis suggest that the length of the boom prescribed by the standard does not guarantee the required accuracy of measurements of ± 1% in the shadow area of the mast, while in all other directions the boom length is overstated. In order to meet the requirements of the standard it is proposed to use two sensors placed in anti-phase with respect to each other. The implementation of the approach would also require that wind speed data is collected along with the wind flow direction indications. Consequently, at any given point in time one of the sensors would be located outside of the mast tail zone and not be subject to measurement distortions. The proposed method for wind speed measurements allows considerably reducing the requirements on the boom length, which would simplify its fastening to the mast, thus reducing the costs of data collection and increasing the reliability of wind energy resource assessment.