Features of a finite-element modeling of a tubular tower for a wind-power unit

Abstract

Introduction. Being indisputably relevant, an identification of the features of modeling tower structures can simplify the work of engineers and simultaneously move the design decision-making to a qualitatively new level.Aim. To assess the effect, caused by some particular features of a computational modelling, on the resulting parameter, representing the frequency behavior of a tubular tower for wind-power units.Materials and Methods. Numerical studies were conducted using a domestic SCAD Office programming and computing suite. In computational modeling, 41st, 42nd, 44th and 50th FE types were used. During the assessment of effects, caused by the finite element type, calculations of a cylindrical tower with fixed parameters were performed, taking into account variations in the type and size of the FE. Estimating factors in calculations included: variations in stresses, as well as in the frequency of first-mode natural oscillations. During the comparison of stress values, the plate of the third from the fixed base row was taken as the design one. Turbowind T600-48 and Eviag EV 100 were considered as wind turbines.Results. A sufficient discretization value of the computational model for determining the frequency of natural oscillations equals to nR = 12, since a further increase in the value of nR will lead to variations in the frequency of natural oscillations by less than 1%. The individual frequencies of 0.275 and 0.825 Hz were determined for an Eviag EV 100 wind turbine. For a Turbowind T600-48, the range of resonant frequencies is determined due to the presence of a variable rotor speed: starting and maximum frequency ranges of 0.255–0.765 and 0.383–1.149 Hz, respectively.Conclusions. During the modeling of a tower in the SCAD Office PCS, it is feasible to use the 44th type of finite elements, taking into account the obtained sufficient discretization value. The obtained spectrum of natural and resonant frequencies allows avoiding the appearance of a resonant effect when making design decisions.