Wind induced interference factor of multirow cooling towers – A glimpse

Abstract

Cooling towers constructed in multi rows with close proximity to each other is becoming common in the recent past, a development that is having profound impact on interference. Most of the studies on multirow towers were focused on the arrangement of cooling towers but the effect of wind direction and spacing of cooling towers were not included and very few studies were addressed either wind directions or specific spacings of grouped towers. Wind direction and spacing of cooling towers have an important influence on interference when compared to the arrangement of cooling towers. Effect of interference on specific arrangements like rectangular pattern, rhombic pattern, L-shaped, oblique L-shaped, etc., are less influenced due to the fact that they are effectively controlled by how the interfering cooling towers are positioned with respect to the principal tower whether it is on windward or leeward or on adjacent sides of the principal tower. Further, the cooling towers embedded in wind flow is usually different from the uniform condition drafted in most wind standards since most structures erected in power plants are embedded in the boundary layer flow. Very few researches have addressed the boundary layer flow conditions. Hence in the present study, systematic wind tunnel testing on several combinations of various spacing/diameter ratios of the representative four tower arrangement of cooling tower models are attempted for various wind directions viz. 0–180° under boundary layer flow condition for the interference function of cooling towers. The interference factor values tend to decrease and vary significantly between the spacing ratios (a/dm) 1.9 and 2.5. It is also observed that the IF value has shown high value for spacing ratio of 1.9 with 30% difference when compared to the values of isolated condition. The IF values corresponding to the 2.2, 2.5, 2.8 and 3.1 spacing ratios are 1.26, 1.197, 1.142 and 1.116 which are higher than the isolated values by about 26%, 20%, 14% and 12% respectively. Further from the analysis, a closed form solution is arrived for the interference of multirow towers.