Investigation into effects of blade inlet/outlet angles and trailing edge shape on flow and noise performances of circulating centrifugal fan in clothes dryer

Clothes dryers (also called tumble dryers) are powered appliances that are used to remove moisture from clothing, bedding, and other textiles. Many dryers constitute a rotating drum called a tumbler through which heated air is circulated to evaporate the moisture. Therefore, the performance and noise of the clothes dryer are greatly influenced by the circulating fan unit. Consequently, it is essential for the development of clothes dryer with high-performance and low-noise to develop high-performance and low-noise fan unit. This study investigate the effects of blade inlet and outlet angles, the trailing edge shape on the volume flow rate, and the radiated aerodynamic noise of the centrifugal fan unit used to circulate the heated air in the clothes dryer. In order to analyze the flow performance and characteristics of the existing centrifugal fan system, a virtual fan performance tester based on Computational Fluid Dynamics techniques is utilized. The validity of the numerical result is confirmed through the comparison of the predicted volume flow rate with the measured one. To improve the flow performance of the centrifugal fan system, the optimization design of the centrifugal fan is carried out using the response surface method for two parameters: blade inlet and outlet angles. As a result, the optimum blade angles are obtained for the maximum volume flow rate. Then, the trailing edge shape, which is known to affect the trailing edge noise, is modified to reduce the aerodynamic noise. Two types of trailing edge, which are of rounding and sharp shapes, are introduced. It is found that the noise performance, as well as the flow performance of the centrifugal fan, are improved through the application of new trailing edge shapes.