CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractWind load is the designed control load for super-large cooling tower (SLCT) structures. Studies on wind resistance of those structures have focused mainly on normal winds, not on the influence of strong typhoons, or in particular the values of suction. To study the suction distribution and action mechanism of flow fields in an SLCT in typhoon conditions, in this study a high temporal–spatial resolution simulation of Typhoon Megi was done using a mesoscale weather research and forecasting (WRF) model with a multiple nesting structure. The wind velocity profile in the simulated region was gained through least squares fit. The research object was the world’s highest cooling tower (220 m) at the Lu’an power plant in Shanxi Province, China. Three-dimensional (3D) computational fluid dynamics (CFD) wind field simulations of this tower in normal-wind and typhoon conditions were done based on a mesoscale–microscale nesting technology. A comparative analysis on the 3D effect of wind loads on the internal surface of an SLCT in a typhoon was also done, as was a summary of the meridian and circumferential distribution laws of the internal pressure coefficients. Differences on flow field characteristics, pressure coefficients, drag coefficients, and wind resistance in the tower structure in normal-wind and typhoon conditions and relative causes were investigated. Finally, the recommended values of suction in an SLCT in typhoon conditions are proposed. Results demonstrate that a WRF–CFD coupling model can effectively simulate the near-surface 3D wind field of an SLCT in typhoon conditions. Compared with a normal wind, the high wind velocity and strong turbulence of a typhoon causes larger-scale vortices inside the cooling tower, a more turbulent airflow on the leeward side, and a longer development area of vortices. In typhoon conditions, the internal pressure coefficient of the tower increased when the ventilation rate of the louver was 15%, 30%, and 100%. The overall internal pressure coefficient was found to be −0.61, −0.36, −0.34, and −0.42 when the ventilation rates of the louver are 0%, 15%, 30%, and 100%, respectively.



Source link

Leave a Reply

Your email address will not be published. Required fields are marked *