Parametric Study of Volutes for Optimal Centrifugal Fan Impellers
3.2 Application of Analytical, Computational and Experimental Methods
European regulations set standards for energy-efficiency of fans, with increasing requirements in the near future. Many studies concerning centrifugal fans have investigated the impeller but to only a smaller extend the spiral casing (volute). The volute may take up a substantial part of the fan's hydraulic loss. Hence, appropriate design of the fan volute has significant meaning to centrifugal fan performance.
Following a current and nearly finished study on aerodynamic optimization of centrifugal fan impellers using CFD-trained meta-models, where a method for optimization of impellers of the whole class of centrifugal fans has been developed, an extension to the volute is envisaged. For that a parametric study of volutes is carried out which should lead to advanced best practice recommendations for the volute design.
Starting point are optimal impellers for the whole range of specific speeds. The detailed flow field at the impeller's outlet from preceding RANS simulations are used as boundary conditions for an RANS of the flow in the volutes. An automized loop with RANS and data post-processing is set up for allowing a large number of parameter variations.
The effect of volute angle, volute width (as a fraction of impeller exit width), geometrical para-meters related to the tongue and axial position of rotor on loss of total pressure and pressure re-covery presented. Selected designs are investigated experimentally for a preliminary validation.