| Turbulence effect is an important subject in structural wind engineering.For a long time,accurate calculation the load of turbulent wind field on the structure is the key bottleneck of wind engineering.Limited by the conditions of producing high-precision and large integral scale incoming turbulence,few numerical investigation involves the effects of high turbulence intensity and large integral scale turbulence on structural aerodynamic loads.In this paper,by combining the high-precision flux reconstruction algorithm with the inflow boundary turbulence generation algorithm,the high fidelity turbulence field transport effects and simulation accuracy are obtained by a large eddy simulation(LES)software package developed by this thesis.The influence of incoming turbulence on the flow field structure and aerodynamic load of an international standard rectangular bluff body model is systematically studied with the incoming turbulence intensity ranged from 6%to 18.5%,and the turbulence integral scale ranged from 2 to 15 folds of characteristic length.,and the relevant mechanism is obtained.The main conclusions are as follows(1)By combining the inflow boundary turbulence generation method with the high-precision flux reconstruction algorithm,in the finite number of grid system,high-precision generation of inflow turbulence and fine resolved turbulence structure transportation are obtained by continuously elevating the accuracy order of flux reconstruction algorithm,while good velocity space correlation orders of magnitude improvement in maintaining the spectral characteristics are achieved.(2)On the basis of reliability validation,the effects of low,medium and high turbulence intensity on aerodynamic load of rectangular bluff body are studied under the condition of fixed turbulence scale.The results show that the instability of shedding vortices in the shear boundary layer increases with high turbulence intensity,which mainly affects the size and location of the main vortices in the recirculation zone.Meanwhile,the frequency and kinetic energy of shedding vortices increase,causing the pressure fluctuation increases in the reattachment flow.Under the condition of constant turbulence scale,the effect of increasing turbulence intensity on the overall aerodynamic load of the model is to increase the fluctuation amplitude in the main frequency band,while the peak frequency of the modal power spectrum is basically unchanged.(3)Under the condition of constant turbulence intensity,the increase of turbulence integral scale leads to the increase of the size of the largest shedding vortex on the upper surface of the bluff body model.When the turbulence integral scale increases to a certain value,a large shedding vortex is formed on the upper surface of the model,and intermittent strong asymmetric flow appears on the side surfaces of the rectangular bluff body,which causes the convergence of vortices on both side surfaces,thus increasing the pressure fluctuation on one side of the model surface.Under the condition of a certain turbulence intensity,the large turbulence integral scale increases the amplitude of pressure fluctuation in a wider frequency band range of the model surface,rather than only increasing the amplitude of the main frequency band of the low-order pressure fluctuation mode,which is different from the effect of increasing the turbulence intensity alone.(4)In this study,a complete set of high-precision numerical methods and models have been developed in this thesis,which can capture the influence of subtle turbulence changes in the flow.It is a good the foundation for further research and resolve the bottleneck of turbulent wind load simulation under the condition of high Reynolds number. |
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