Effect of twisted blade roots on the performance and internal flow of non-volute centrifugal fan

In this paper, the effects of twisting blade roots on the performance and internal flow of the non-volute centrifugal fan are deeply studied by means of computational fluid dynamics and experiment tests. The midpoint of the blade root centerline as the twist center is defined and the twisting deformation is applied to both the leading and trailing edges. The pressure distribution inside the impeller is effectively improved by moderate blade root twist, the flow separation and secondary flow loss are also effectively reduced. The flow characteristics at the high angle of incident are mainly improved by the twist angle. At the design flow rate, the static pressure efficiency of the fans with twist angles of 5°, 15°, 25°, and 35°increased by 0.2%, 4.89%, 5.27%, and 4.38%, respectively compared with that of original centrifugal fan. It is obtained that at the low flow rate 0.9 Qn, the static pressure efficiency of the twist 5°, 15°, 25°, and 35° models are increased by 1.1%, 4.74%, 8.31%, and 8.88%, respectively compared with that of original centrifugal fan. However, at high flow rate, an excessive twist introduces a new separation zone and increases the length of the flow channel and aggravate the friction loss. The static pressure and static pressure efficiency of the twist 25°model arise as much as 2 Pa and 1.14% compared with that of the original non-volute centrifugal fan by experimental measurement and total pressure and total pressure efficiency of the twist 25°model arise as much as 12.4 Pa and 1.27%, respectively. These findings provide critical insights for optimizing centrifugal fan design through localized blade geometry modifications. In particular the part-load efficiency of centrifugal fan is effectively enhanced in engineering application.