Substantiation of Life Extension Method for Two-Stage Axial Flow Fans for Main Ventilation

Resumo

The article substantiates the retrofit method for two-stage axial flow fans including an impeller and a flow straightener in each stage. In this method, the two-stage rotor is replaced by a high-rate one-stage rotor within the inlet guide vanes-impeller-flow straightener circuit. As a result, the air flow at the impeller input is uniform per standard, the operational life of the rotor bearing assembly is extended while the rotor mass is largely reduced. The procedure is developed for design and selection of aerodynamic and structural parameters of the remodel axial mine fans. The procedure takes into account the influence of the variable frequency drive and gyroscopic moment of the impeller, as well as the rigidity of the bearing assemblies and ratio of mass-inertia properties of the rotor, which allows determination of critical rotor speeds at early stage of design.