Abstract:
Different interference effects on global wind loads and wind induced responses for group hyperboloidal cooling towers (HCTs) were studied based on wind tunnel tests on rigid models and dynamic calculations of wind induced structural responses. The basis of the study was the different influences of latitude wind pressure distribution on the drag coefficient
CD and meridian axial force
FT. In group-tower conditions, interference effects on the wind pressure distribution of the target tower can be classified into three types: shielding effect from the upwind tower in tandem and staggered arrangement which decreases the windward pressure (Ⅰ); drawing effect from the downwind tower in side-by-side and staggered arrangement which increases the leeward suction (Ⅱ); wake vortex induced effect from the upwind tower in tandem and staggered arrangement which increases the fluctuating pressure in windward and sideward areas (Ⅲ). These three effects exert different influences on
CD and
FT.
CD is mainly determined by the windward and leeward pressure, hence effect Ⅰ and Ⅱ result in drop and rise of the mean
CD respectively. Stronger fluctuating latitude pressure induced by effect Ⅲ leads to greater Root Mean Square (RMS) of
CD. However,
FT is mainly determined by the windward and sideward pressure, therefore effect Ⅰ and Ⅲ result in drop and a rise of
FT respectively and effect Ⅱ hardly alters
FT. Compared with the single tower condition, the aggravation of
FT in group towers mainly stems from the increase of the fluctuating pressure. For group towers with a commonly-used tower distance, the sensitivity of interference effects to wind direction is much greater than that to the distance amongst towers. For group-tower layouts, the range of adverse wind directions for the double-row layout is wider than that of a single-row layout. According to the present study, the tower layout and wind direction indeed amplified the
FT of the collapsed towers located in the back row when the Ferrybridge accident happened.
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