Investigation of surface roughness and its influence to flow dynamic characteristics of hyperbolic cooling tower

The flow characteristics around the hyperbolic cooling tower model with circular cross section in the wind tunnel experiments are sensitive to Reynolds number. How to get the accurate Reynolds number effects in the wind tunnel tests for super large cooling towers is still a tough task for structural wind engineers. Up to now, engineers have not been able to get the precise values of some dynamic characteristic parameters induced by fluctuating wind due to the shortcomings of early quasidynamic sensors. Meanwhile, it is noted that these parameters play important roles in the design process of super large cooling towers which are higher than 165m. This research is based on a 235m high super large cooling tower on the planning. By external pressure wind tunnel tests of the rigid model with scale of 1∶200, a detailed study on the super high Reynolds number effects of the tower are carried out and some valuable conclusions are gotten after the tests. (1) The influence of the surface roughness to Reynolds numbers effects is sensitive to the flow characteristics; (2) The higher wind speed should be firstly chosen in the wind tunnel tests on the same condition; (3) The best simulation measurements should consider the distribution of mean and fluctuating wind pressures of the models critical sections, drag coefficients and Strouhal number together; (4) Whether the Strouhal numberReynolds numbers curve of circular cylinder is suitable to super large hyperbolic cooling towers with changing sections in altitude direction should be checked by field tests in the future.