INTERFERENCE EFFECTS ON COOLING TOWERS

Abstract

The modem trend of design and advancement in technology, have resulted into lighter and higher structures. As a result they have become sensitive to wind loads. Wind loads play an important role in the design of such structures. The design codes have been modified and made stricter with regards to such loads. Cooling towers, chimneys, tall buildings and towers such as lattice towers come under this group of structures. Due to the effect of interference of surrounding structure the codes suggest for experimental investigation to assess the aerodynamic behavior of these structures. Natural Draught cooling towers are prominent features in many Thermal and Nuclear Power Stations in view of their large size. These Towers Rank among the largest reinforced concrete thin shell structures. The thin outer shell of natural draught cooling tower can be said to be one of the greatest structural innovations of all times. The thickness of shell is as little as 170 mm, for a height of over 150 m. Therefore its analysis and design demands precision and care. For Natural Draught Cooling Towers the codes suggest the wind loadings for the isolated towers which are on the conservative side, but practically the towers are not isolated but surrounded by the other towers or the power plant and other surrounding buildings. The presence of the other structures affects the wind loadings. This effect is called interference effect. Therefore it has become necessary to determine the effect of wind in such cases experimentally or numerically. Experimental testing is carried out in Boundary Layer Wind Tunnels (BLWT).