NEWPAN2D Aerofoil Design Projects: The Glasgow Wing Tower

At 100m, the Glasgow Science Centre Tower is the tallest free-standing structure in Scotland, and the world's first tower to rotate through 360 degrees in response to the wind. Visitors ride by lift to a cabin at the top of the tower, affording spectacular views. With a width to height ratio of 1:13, the tower is 60% more slender than conventional structures.

With such a slender tower aerodynamic effects could cause strong movements at the top which would be very uncomfortable for visitors. Careful aerodynamic design was critical in order to transform the aesthetically pleasing architectural design into structural reality.

The tower is effectively a vertically mounted wing, which is turned into wind to reduce its drag. The design needed to achieve a steady wake when oriented into wind.

Hence the challenge facing Peter Heppel and architect Richard Horden Associates, working in partnership with the project engineer Buro Happold, became clear. They needed to design aerofoil profiles for the tower which would meet the structural constraints whilst providing attached flow, low drag and a small lift curve slope to minimise transverse buffeting.

Flow Solutions' NEWPAN2D aerofoil design software, and its forerunner known as ADAP, was used to provide solutions to these requirements. The profiles of the various components were developed using the two-dimensional panel-method program in order to design profiles with minimal flow separation at low incidence.

The significant elements involved are the size and shape of the stair tower and the profiles of the outriggers. The stair enclosure chord was made as short as possible in order to reduce the overall lift-incidence slope. The chord, in isolation, would be too thick to allow unseparated flow. However, by using two supplementary foils it was possible to change the recovery profile on the tower. These outriggers generate a lift coefficient of about 1.3 inwards, which reduces the base pressure on the stair enclosure and significantly retards separation. The outriggers have thick, highly cambered profiles, and their thickness is determined by structural requirements. The mean line was chosen to give a lift coefficient of about 0.9 and an external profile that met the architectural requirements.

About 50 forms and configurations were evaluated. Detailed design was performed using the inverse design mode of ADAP/NEWPAN2D, in which the program calculates the shape required to achieve a user-specified pressure distribution. The result was a design achieving attached flow on a 48% thick aerofoil.