Browsing by Author "Marincowitz, Fredrik Simon"
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- ItemExperimental investigation of the effects of windscreens on air-cooled condenser fan performance and dynamic blade loading(Stellenbosch : Stellenbosch University, 2019-04) Marincowitz, Fredrik Simon; Owen, M. T. F.; Muiyser, Jacques; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering (CRSES)ENGLISH ABSTRACT: Air-cooled condensers (ACCs) are the preferred cooling method for power plants that make use of the Rankine cycle in regions that have limited water resources. However, using air as the cooling fluid has its limitations as environmental conditions such as wind affects ACCs thermal performance. Wind specifically influences the ACCs perimeter fans, as the strong cross-flow caused by winds results in distorted inflow conditions which lead to a reduction in fan performance and excessive dynamic blade loading. One method used to mitigate these effects is the use of windscreens along the perimeter of the fan platform, but studies done on this topic are however inconclusive as computational fluid dynamics (CFD) studies indicate windscreens help increase perimeter fan performance while site specific full-scale experimental studies indicate windscreens are mostly beneficial in reducing the dynamic blade loading. As the exact influence of windscreens on the perimeter fans appears to be not well understood, a controllable and repeatable experimental investigation was deemed a good method to aid in this understanding. This experimental investigation was then done on a scaled ACC fan row at a fixed platform height, consisting of 3 fans, and subjected to a controllable cross-flow to simulate wind. Using this test setup, the fan performance and dynamic blade loading under strong cross-flow could be investigated and used as a baseline to compare with the results once a windscreen was installed. The results indicated that with increasing cross-flow the performance of the perimeter fan suffered increasingly due to the formation of a separation region on the upstream edge of the bellmouth. This then resulted in a significant difference between the up-and downstream velocity profiles into the perimeter fan (perpendicular to the blade) which led to an increase in the dynamic loading on the fan blade. With the installation of a windscreen the perimeter fan’s performance was mostly negatively affected as the majority of the incoming flow was deflected away from the intake of the perimeter fan, and the flow permeating through the windscreen was insufficient to help improve the performance. In most cases the windscreen did however help to reduce the difference in up-and downstream velocity profiles into the perimeter fan, reducing the dynamic blade loading on the perimeter fan. Where the fan performance results with and without a windscreen, for the scaled ACC fan row, had very similar trends to that recorded at a full-scale facility of a similar dimensionless platform height which instilled confidence in the experimental methods used.