Sound Radiation of a Cooling Tower

Abstract

Whereas most other objects in this book are more or less arbitrary examples for the demonstration of a numerical method, the objective of this chapter stems from a concrete task. The electric power plant in Neckarwestheim was to be extended by a second station with a higher power production. The plant is situated in a bow of the Neckar river and the city of Neckarwestheim is arranged on a hill slope around the plant like the seats in an amphitheatre. If the cooling tower required for the power of the second station had been constructed in the usual manner with thermic ventilation their huge size would have blocked the view over the Neckar valley. Therefore it was planned as a “hybrid” cooling tower with ventilator-driven ventilation. The hybrid cooling tower has a larger diameter than the conventional cooling towers but a much smaller height. The small height has the consequence that the inhabitants of Neckarwestheim can look from above into the cooling tower. Therefore high noise pollution was feared from inside the cooling tower by the flow noise of the ventilators and by the “waterfall noise” of the cooling water. It should be investigated whether the noise radiation from the tower orifice can be reduced with an absorbent coating on the interior side of the tower wall, and if this is possible where and in what size with which absorption coefficient the absorber should be applied. For this purpose a model of the cooling tower in a scale factor 1:40 was built for experimental studies. According to the results it was recommended to apply an absorbent lining on about 1/4 to 1/2 of the periphery over the upper third of the tower height on the interior side opposite to the city [34, 35] (Fig. 16.1).