Study of the Effect of Fan Tip Configuration on Air-Cooled Condenser Axial Flow Fan Performance

D3 - Fan Performance (i)

Large air-cooled heat exchangers (ACHEs) and air-cooled condensers (ACCs) are popular in countries such as South Africa where water is scarce and wet cooled systems are not viable. These systems consist of heat exchanger bundles which have multiple large axial flow fans mounted below or above them. Due to the scale of ACC units at large power plants such as Eskom’s Matimba plant, the fans are major power consumers. Therefore it is desirable to make the fans as efficient as possible in order to reduce power consumption and increase plant efficiency.
Research has indicated that the blade tip region plays an important role in the performance of axial flow fans. The configuration of this region has a profound impact on both fan performance and - noise. Tip clearance tests conducted by Kröger and Venter (1992) on the "V-fan" indicate a correlation between tip clearance and fan static efficiency. Research undertaken by Corsini et al. found that endplate configurations for fan blades have an impact on both fan performance and noise (Corsini et al., 2007). It was therefor decided to combine an investigation into fan blade endplate configuration with an investigation into fan blade tip clearance and to measure the effect of these on the performance of an axial flow fan.
The experimental fan used in this investigation was the 1.5 m diameter B2-fan, which is a 1/6th model of a fan that was developed specifically for use in large ACCs. The experiments were performed on a standard BS848 type A fan test facility. The first set of tests consisted of blade angle and tip clearance tests. Based on these results an updated correlation for the effect of tip clearance and fan static efficiency was derived and compared to the results of Kröger and Venter. Using the results of the first set of experiments, several basic endplate configurations were tested at the optimum blade angle and the ideal tip clearance value. The results of this investigation were used to derive an improved blade endplate configuration and tip clearance combination.
The results of this research indicate that a specific combination of tip clearance and endplate do make a significant difference to the performance of an axial flow fan. Such a configuration may either increase or decrease the static efficiency of the fan at its operating point, depending on the configuration used.


Kroger D.G., Venter S.J., 1992. The Effect of Tip Clearence on the Performance of an Axial Flow Fan. Energy Conversion and Management, 33(2), pp. 89-97.
Corsini A., Rispoli F., Sheard, A., 2007. Development of improved blade tip endplate concepts for low-noise operation in industrial fans. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, Volume 221, pp. 669-681.