Common blade design techniques are based on the assumption of the airflow laying on cylindrical surfaces. This behaviour is proper only for free-vortex flow, whereas radial fluid migration along the span is always present in case of controlled vortex design blades. The paper presents a design procedure to increase aeraulic efficiency of fan rotors originally designed using a controlled vortex criterion, based on the assumption that a blade section positioning taking into account the actual airflow direction could be beneficial for rotor aeraulic performance. The proposed procedure employs a three-dimensional aerofoil positioning and blade forward sweep. The procedure is applied to a rotor-only tube-axial fan featuring a 0.44 hub-to-tip ratio, an almost constant swirl velocity distribution at the rotor outlet and a quite low blade Reynolds number. Rotor prototypes deriving from step-by-step blade modifications are experimentally tested on an ISO 5801 standard test rig. Results show the importance of considering radial fluid migration for highly loaded rotors.


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    Title :

    Forward sweep to improve the efficiency of rotor-only tube-axial fans with controlled vortex design blades




    Publication date :

    2016




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    52.50 Energietechnik: Allgemeines / 52.30 Strömungskraftmaschinen, Turbomaschinen / 52.30 / 52.50
    Local classification TIB:    275/5345/5365/5500






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