Investigation on the comparison analysis of the characteristics between the Forward and Backward curved fan system and the Improvement on flow/noise performances by optimizing blade angles in clothes dryers

Abstract

Recently, the needs for clothes dryers are rapidly increasing due to the consumer's interest in convenience for time reducing and cleanliness like dust. The drying performance of these clothes dryers is greatly affected by the fan system. The fan system affects the flow performance and is related to drying time of clothes dryer. Also, the aerodynamic noise generated by the fan system in the dryer has a great influence on the overall noise of the machine. Because of these reasons, many manufacturers are conducting researches on improving the performance of the fan system in the dryers. The purpose of this study is to improve the flow & noise performance of a fan system in clothes dryer using CFD (Computational Fluid Dynamics) and acoustic analogy based on FW-H (Ffowcs-Williams and Hawkings) equation. The numerical analysis on the flow characteristics of the fan system is conducted by ANSYS FLUENT. The 3-dimesnsional incompressible RANS (Reynolds Averaged Navier-Stokes) equation is adopted as the governing equation and the SST k-ω model is used for turbulent model. The integral surface for FW-H equation to analyze the acoustic field is composed of the closed surfaces including the scroll. This study investigates more suitable fan for a dryer system by comparing the flow characteristics of a backward curved fan, already adopted to a dryer, with a new forward curved fan which has same diameter. To improve the flow performance, the blade angles have been tuned by the design optimization which is the response surface method for geometric parameters. As a result, the dryer with the forward curved fan, which had optimal blade angles, reduced the rotating speed with the same volume flow rate as the original fan. And finally it showed the much reduced noise level compared to the original fan when the dryer ran.