Aerodynamic and acoustic studies on a radial fan family developed for increased specific flow rate of dust-laden gases

Authors

Bálint Kocsis - Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Hungary
Tamás Benedek - Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Hungary
Péter Ferenczy - Szellőző Művek Kft., Budapest, Hungary
Esztella Balla - Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Hungary
Gábor Daku - Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Hungary
János Vad* - Budapest University of Technology and Economics, Faculty of Mechanical Engineering, Hungary

Abstract

Product families of fans applied in industrial air technology and ventilation are developed to correspond to application-specific demands. The paper presents a recently developed radial fan family, designed for an increased resistance against the particles of solid contaminants, and for an increased specific flow rate. High specific flow rate is represented by relatively high flow coefficients, i.e. realizing a relatively high gas flow rate even at moderate rotor diameter and/or rotor speed. The reduced rotor size supports the applicability of fans of moderate space demand and reduced weight for a given assignment in industrial gas transportation. Furthermore, the reduced circumferential speed of the rotor enables a moderation of mechanical stresses occurring in the rotor, and potentially contributes to a reduction of fan noise. The paper outlines the preliminary design of the fan family, together with a synopsis of the iterative aerodynamic development of the fan family, incorporating Computational Fluid Dynamics (CFD) efforts. As instructed by the industrial customer, backward-leaned uncambered - i.e. straight - plate blades were to be considered for the rotor in design, in order to moderate the inclination of the blading to erosion or deposit formation due to the dust load. Despite the relatively simple, easy-to-manufacture rotor geometry, the careful CFD-assisted design process resulted in a reasonably high fan efficiency, significantly exceeding the efficiency criterion dictated by the EU 327/2011 Fan Regulation. The paper provides a detailed description of prototype testing. The characteristic and efficiency curves on fan prototypes were obtained over wide operational ranges, with special regard to the overloading - i.e. higher-than-design - flow rate range, bearing in mind that a demand by the customer was to realize high specific flow rates at reasonably high efficiencies. The effect of increasing the rotor width has also been investigated in prototype tests, in order to assess the possibility of further increasing the specific flow rate of the fan family by such means. Emphasis has been put on the Industry 4.0 perspectives of the application of the new fan family, with special regard to possibilities of non-contact, acoustics-based condition monitoring of the fans. To this end, preliminary acoustic studies were carried out on the fan prototypes, with use of the Phased Array Microphone (PAM) technique. The fan prototypes have been subjected to PAM studies for various operational states. With use of the PAM technology, the spatial and spectral distribution as well as strength of noise sources related to the fan prototypes have been identified. By such means, noise-radiating zones, being potential candidates for purposeful sensing of the fan noise with condition-monitoring aims have been identified. The noise detected for various operational states was compared to literature-based reference data. The perspectives of acoustics-based condition monitoring related to the new fan family have been assessed.