Investigation On Reynolds Number Effects Of Wind Loads On Rectangular Super High-rise Buildings By Wind Tunnel Test

In wind tunnel test’s scale effects, the Reynolds number effects are universally accepted as the most classical and the most famous difficult problem. For it is impossible to simulate the Reynolds number as high as the structural actual wind field in wind tunnels. The error caused by the Reynolds number effects in wind tunnel tests has been one of attention keys in the structure wind engineering research region.For a long time, with little knowledge about Reynolds number effects of rectangular buildings and careless about them, scholars usually neglect the Reynolds number effects on the surface wind pressure fields of rectangular buildings. But the existent studies show that there did be Reynolds number effects in different degrees on the surface wind pressure fields of rectangular buildings as well as those buildings whose cross sections with sharp corners. In this paper, by using the approachs of pressure-measuring and force-measuring tests of rigid model in wind tunnels, a series of researches have been accomplished on Reynolds number effects of the wind loads on rectangular high-rise building:1. In uniform smooth flow field, by changing wind velocity in wind tunnel and model dimension, Reynolds number effects on surface wind pressures and 3-D aerodynamic force coefficient of rectangular building models with different side ratios as well as square buildings whose corners are cut have been studied. Some conclusions are obtained, which may help wind tunnel tests in the future.2. Manufacturing Turbulent flow by using the grill, in 5% and 15% uniform turbulent flow fields simulated in wind tunnel, by changing wind velocity and model dimension in wind tunnel test, Reynolds number effects on surfaces wind pressure and 3-D aerodynamic force coefficients of rectangular building models with different side ratios as well as square building models whose corners are cut have been investigated and analysed. On the basis of these, whether it is feasible to control Reynolds number effects of surfaces wind pressure and aerodynamic force coefficient by increasing the turbulent intensity has been investigated. It shows that Reynolds number effects can be relieved by increasing turbulent intensities to a certain extent.3. Using spires and cubic elements to simulate B and D categories of terrain in wind tunnel, the characteristics of surfaces wind pressure and 3-D aerodynamic force coefficient changing along with Reynolds number in B and D categories of terrain have been investigated. The Reynolds number effects of the generalized wind force of the first mode on rectangular buildings in B category of terrain have been studied by analysing force-balance data of rectangular buildingmodels in wind tunnel tests.4. Using the rough strips to increase the model surface roughness, whether it is feasible to control Reynolds number effects on surfaces wind pressure and 3-D aerodynamic force coefficient by changing surface roughness has been studied in this paper. The researches indicates that certain physical quantity (for example:drag coefficient and leeward wind pressure) may obtain similar characteristics as high Reynolds number wind field by inceasing the surfaces relative roughness to 0.02 in low Reynolds number wind tunnel.5. The Reynolds number effects on along-wind and across-wind force spectra of rectangular building models with different side ratio have been studied, and characteristics of St number of the building models with different side ratios changing along with the Reynolds number have also been studied. It shows that the distribution characteristics in frequency domain of wind spectra of rectangular building models and their St number do not change obviously with the increase of Reynolds number.In brief, the Reynolds number effects of rectangular building models are very complicated and are with high requests to the test condition. With limited time and condition, only some gradual results have been achieved in a certain Reynolds number scope in this paper, and the results can provide certain references for the wind engineering to make an intensive study on rectangular high-rise building’s Reynolds number effects.