HIGH PRESSURE AXIAL FLOW FANS FOR POWER INDUSTRY

Two high pressure axial flow fan stages with hub/tip ratio of 0.6 were designed for advanced coal power stations. Stages had a design flow coefficient of 0.60 and 0.35 and the design pressure coefficient of 0.83 and 0.45. New stages had a maximum attainable design pressure coefficient at a maximum efficiency of 90%. Maximum diffusion factors of the rotor and stator row blades were less than 0.60. An experimental verification of the new stages on a test rig with an external diameter of 600 mm confirmed the achievement of the design targets. The stages aerodynamic design was analysed within a range of the rotor blade stagger angle variation of +/- 20 degrees using the blade test performance data obtained by means of traversing 5-hole conical probes. The application of bowed stator blades, the stage with the design flow coefficient of 0.35, increased the aerodynamic performance at working points with positive stator incidences. The fan efficiency decreases with the energy losses of the inlet chamber and the diffuser and it decreases with an increase in flow coefficient. This trend is weakened by the growth of the fan stage blading pressure coefficient. Test results support these conclusions.