AN EXPERIMENTAL DETERMINATION OF NET PRESSURE COEFFICIENT FOR MULTI-STOREY BUILDING USING AN EIFFEL TYPE WIND TUNNEL TO GENERATE A COMPRESSIBLE AERODYNAMIC FREE STREAM FLOW

The research work focuses on the experimental determination of net pressure coefficient for 72m, 20-storey building using an Eiffel type wind tunnel to generate a compressible aerodynamic free stream flow. By using mathematical models developed by notable scholars; some of the grey areas leading to confusion in the use of the terms compressible and incompressible flow were discussed. Subsequently, two models of scale 1: 300 for model height were constructed with Afra timber because it was easy to machine to various shapes and sizes. Pipettes, brazen and suitable flexible rubber tubes were used for the construction of the improvised manometer used to measure the external pressure around the perimeter of the models. A scale of 1: 3 was used for site (i.e.52 ms^-1; Bauchi - Nigeria) – Tunnel (i.e.17.5 ms^-1) wind speed. The investigation shows that, there is equilibrium of the pressure between the static and the dynamic pressures at a value of 81mm. The maximum and minimum values for the static and dynamic pressures are respectively 112mm / 48.5mm and 125mm / 33mm respectively. Similarly, the net pressure distributions of the four faces (A, B, C and D) of the model were investigated and the pressure increases with a maximum at the model height of 152mm (C). The value at this height is approximately 1.28. Above this height there is a drop of approximately 3.13% but the average net external pressure coefficient is 1.187. This value differs by 1.10% from 1.2 recommended by BS 6399; part 2 (2004).