ACROSS WIND RESPONSE OF TALL CHIMNEYS

Abstract

In the present age of rapid industrilisation, chimneys are very useful for effective and safe disposal of industrial waste gases into the atmosphere. Their heights are increas-ing day by day reaching to 300 m. to meet the anti pollution requirementVi Due to increased height the effect of wind predominates in the design of chimney. The wind force may be considered in the direction of wind or along wind and prependicular to the direction of wind or across wind sppera.- tely. Along wind excitation is due to gustiness of wind while across is mainly due to periodic shedding of vorticies Under winds. In the present study, there is an attempt to analyse and compare the along wind response obtained by approach given by Davenport, and in case of across wind by approaches given by Rumman and Vickery. Two types of chimneys, one having constant taper throughout the height and second having constant diameter in upper half portion and constant taper in lower half portion are analysed. The heights of chimneys are taken as 100 m.,150 m, 200 m and 250 m, and for different top diameter to base diameter ratios, verylng from 0.35 to 0.65, the responses have been computed