Browsing by Author "Van Jaarsveld, Nicolaas Vlok"

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    An investigation into using fan blade loading as an axial flow fan performance and scaling parameter
    (Stellenbosch : Stellenbosch University, 2023-03) Van Jaarsveld, Nicolaas Vlok; Meyer, C. J.; Van der Spuy, S. J.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH SUMMARY: Air-cooled condensers (ACCs) utilise axial flow fans to produce airflow over heat exchangers. The size of these fans makes it challenging to determine their performance characteristics experimentally. Current methods of determining a fan's installed operating point exist, but each method contains significant inaccuracies. A new metric was investigated with the goal of improving the prediction of a fan’s installed operating point. The fan under investigation is the M-fan (7.31 m in diameter) designed for application in ACCs installed at concentrated solar power plants. Stellenbosch University has the facilities to test the model M-fan in a standardised testing facility and a large M-fan in its installed environment. Fan static pressure measurements are advantageous for use in fan characterisation due to the steep slope of the fan static pressure characteristic. The generation of thrust by an axial flow fan blade is the cause for the rise in static pressure across the fan, leading to the expectation that a proportional relationship exists between the axial fan blade loading (blade thrust) and the fan static pressure rise. The use of fan blade thrust to determine a fan’s installed operating point, in conjunction with fan power, was therefore investigated. During investigation of a model-scale system, the use of fan blade loading to determine a fan’s operating point was deemed successful. When compared to the fan characteristic curve, the measured fan power corresponded to a volume flow rate of 16.21 m3/s, whereas the flap-wise strain corresponded to a volume flow rate of 15.96m3/s. The difference between the two predicted volume flow rates is 1.55%. Following an extensive experimental analysis, the use of fan blade loading was deemed successful for use in large-scale fan performance prediction through scaling with the square of the geometrical scaling factor (GF2). A difference in fan power and fan blade loading was, however, observed between the scaled model fan characteristics and the large-scale test results. The scaling laws underpredicted the fan power by an average of 9.54 %. A further slight decrease in fan power was observed at high volume flow rates. The former shows a near-perfect correlation between an increase in blade setting angle, whereas the latter represents a similar trend to that of distorted inflow conditions.