Research On Reynolds Number Effect Of Dome Roofs In Turbulent Flow

Characteristic of wind flow around a bluff body will have some distinct while its Reynolds number changes. Characteristic of wind pressure around structure relate to Re as well. It is 100 times that Re of real architecture larger than model in wind tunnel test. Some essencial research for Reynolds number effects, as a result, should be raised as a fundational problem on structural wind engineering. The research of Reynolds number effects is still in a theoretical exploration stage. Researchers always concentrate on single circular column and cylindrical roof without dome. They spend a great deal of time researching aerodynamic behaviour of bluff bodies which stays in wind flow with different Re by using mean pressure coefficient, lift coefficient and drag coefficient. While, the Reynolds number effects can be attributed to the differences among the flow state, surface boundary-layer separation and vortex effects, some research on RMS pressure coefficient and vortex structures should be taken. This work attempts to study about the Reynolds number effects on dome with 1/4 rise-span ratio. The main content can be summarized as follows:(1) A series of wind tunnel tests was performed to investigate the effects of Re on the aerodynamic characteristics of dome with 1/4 rise-span ratio in smooth and turbulent boundary layer flows. Re of this study varies from 8.48×104 to 2.06×106 in smooth flow and from 9.66×104 to 1.38×106 in boundary layer flow. The result indicate that, in smooth flow, the transition of separation flow occurs in-between Re=1.10×105~2.48×105(Re=9.66×104~2.07×105 in boundary layer flow).(2) Two vital methods of Reynolds number effect was summarized. One of them is how to find the Reynold transition zone, the other is the way of analysising vortex by using POD and SPT.(3) Distribution of mean and RMS pressure coefficient, gradient coefficient, lift and drag coefficient in smooth flow with different Re is studied. Ttransformation of these parameter's distribution in turbulent boundary layer flow is also studied as a contrast. Transition Reynold stays 2.48×105 in smooth flow and it comes to 2.07×105 in boundary layer flow.(4) Spectrum analysis is used to inquire the rhythm and spectra characteristics in frequency domain. The peak value's movement of wind pressure spectra in different Re is concluded. Energy transfers from low frequency to high frequency as Reynold number increasing.(5) Proper orthogonal decomposition is used to find the dominating model of the fluctuate wind field.Then classic vortex structures at dominant rhythm is acquired by using the spectral proper transformation.