58505 - Feasibility Study on the Effect of Blade Inclination for Heavy Duty Centrifugal Fans ‒ Aerodynamic Aspects 

Heavy-duty centrifugal fans require high reliability and first-class performance. Besides, extreme conditions and harsh environments are often encountered, such as in the papermaking process, in steel or cement plants or the chemical and petrochemical industry. Therefore, the design of high performance heavy-duty industrial fans requires robust yet efficient solutions. This particularly affects the fan blade design process and hinders the implementation of high-dimensional and complex blade profiles of filigree structure. For this reason, with a special focus on the industrial feasibility and the manufacturability, a recently proposed novel approach to centrifugal impeller blade inclination is adopted and investigated through extensive CFD analysis. The fan blades, originally aligned perpendicular to the impeller backplate, are inclined by the inclination angle δ in either forward or backward direction, with the axis of rotation defined by the blade chord on the impeller backplate. Contrary to the approach proposed in the literature, the current study aims to assess the feasibility of blade inclination for fan impellers including the volute housing of the fan, an issue that has been disregarded in previous studies. Fur the presented study an industrially proven fan design is chosen for testing. Compared to the original design, the inclined fan blades possess an increased total blade area and at the same time providing variable inflow angles at the leading edges of the blades. These two factors are expected to alter the fan characteristic curves in providing an increased range of optimum performance while maintaining high aerodynamic efficiency. The results obtained show a clear trend in aerodynamic performance with the degree of inclination, where the characteristic curves rotate at about the design point, allowing local improvements either in the pre-stall or the stall regime of the fan. Moreover, the trends obtained show the tendency to agree well with the rudimentary models published in previous studies, even though it appears to be affected by the fan volute and the point of operation as well. For providing the full picture, the results obtained motivate further investigations to analyse the aeroaocustic signature as well as the vibration characteristics and aspects in the analysis of mechanical strength.