Remarks On The Meridional Design Of Mixed Flow Fans

Abstract

Due to a large range of application areas for fans in the industrial, the household and the agricultural sector, there are already many fans of different types, in different shapes and sizes available at the market. If the design point requires large flow rates with a sufficiently large increase in pressure, the recommended fan type is between the axial and radial fan type, within the range of mixed flow fans. But there are only very few recommendations for mixed flow fans design methods available in the literature. In order to prevent a shroud separation in the mixed flow fan, 3 different radii (R80, R130 and R180) were investigated. An increase in pressure and efficiency of the mixed flow fan with the radius R130 was determined by the measurement results. The influence on the characteristic curves of different downstream angles Chi (χ) between χ= 30° (almost axial) and χ = 90° (radial) was investigated in terms of pressure rise, flowrates and efficiencies. The mixed flow fan with a downstream angle of χ= 68° has increased flow rates with better efficiencies compared to the investigated centrifugal fan. The mixed flow fan type already achieves higher pressure rises in a single stage than axial fans and can be easily integrated in fluid systems with axially parallel inlet and outlet flow. They represent a serious alternative in the application field between axial and radial fans.