Research on effects of geometric characteristics on critical Reynolds number ranges of cylindrical roofs in wind tunnel

There is a strong dependence of aerodynamic loads for large-span cylindrical roofs on Reynolds number effect, and the Reynolds number sensitivities are greatly influenced by the geometric characteristics of the roofs. As a result, based on the series of Reynolds number tests of cylindrical roof model, the influences of geometric parameters on the Reynolds number effects were investigated. Different rise to span ratios (f/L was from 1/6 to 1/2) and width to span ratios (B/L was from 1 to 12) were considered, and the Reynolds numbers ranged from 6.90×10⁴ to 1.38×10⁶.Based on the data derived from wind tunnel tests, the wind pressure distributions, pressure gradients and lift and drag force coefficients were analyzed. The test results show that there is a direct shift of the transitional Reynolds number towards high Re level owing to the increasing rise to span ratio, whilst the decreasing length to span ratio. This reveals that three-dimensional flow will postpone the transition of separated shear layers from laminar to turbulent over the roof surface. The lower limits of critical Reynolds number increases from 1.66×10⁵ to 4.14×10⁵with B/L decreasing from 12 to 1, whilst the lower limits increases from 2.48×10⁵ to 4.14×10⁵ with f/L increasing from 1/3 to 1/2. There is no Reynolds number effect for cylinder roofs with f/L of 1/6 in the range of test Reynolds number from 6.9×10⁴ to 2.48×10⁵.