The impact of wind on solar towers
Wind has a big effect on tall buildings and it is essential that this is taken into consideration when designing them to ensure they are structurally safe. Since they are so tall, solar towers need to be designed to cope with various different strengths of wind.
The loads resulting from pressure applied by wind vary, so monitoring and evaluation are required over long periods of time to correctly identify the strengths of the forces generated.
” In areas that are exposed to strong wind, this wind can become an important factor to consider during structural design.
In order to do so, two mathematical models are currently used to establish the impact of gusts based on the height of the buildings in question, with the use of these models being subject to local legislation: the potential model is used in countries like the USA and Chile, while the logarithmic model is used in Europe.
In some exceptional cases where the building has an unusual shape or location, more precise systems or experiments may be used to provide additional information on how to further strengthen the structure.
This is the case for the solar tower used in the Atacama I project that Abengoa is developing in the Chilean desert. The concentrated solar tower is around 250 m tall, has an unusual shape and is in a highly seismic area.
” Due to the location and characteristics of Atacama 1, additional systems were used alongside those required by regulations to optimise its structure.
In this case, mathematical modelling was used in conjunction with experiments, such as testing in a wind tunnel, to optimise the design and ensure the structure would be stable in strong winds.
The tests consisted of setting up a scale model of the building and its environment in a tunnel with variable wind strengths similar to those in the intended location of the building.
The aerodynamic research for the tower designed for the Atacama I project was carried out in Canada by a company specialising in wind engineering. The testing was performed using a 1:400 scale model on a rotating platform in a wind tunnel capable of simulating the winds of the Atacama desert. This test discovered how stable the structure remained in the wind and identified how it moved with gusts of wind, establishing the solar tower’s aerodynamic profile and allowing its design to be optimised.
Another procedure the Atacama project used during the design phase is computer modelling, using Computational Fluid Dynamics (CFD). In this case, the natural wind generator, developed by the Technical University of Munich for Abengoa, and the XFlowCFD software reproduce the wind characteristics to obtain detailed information about aerodynamic resistance and forces exerted by the wind over the tower, much like a wind tunnel does.