Radial tipped blades
The radial tipped blade design is represented diagrammatically in Figure 1.69.
Figure 1.68 Backplated paddle impellers
This blade form is used as an alternative to the shrouded radial. Generally there is an increased number of blades and the heel of these is forward curved to reduce shock losses. The efficiency and flowrate are therefore improved for a given size, but the characteristics are otherwise similar. Fan static efficiencies up to 73% are possible.
The units are widely used for induced draught on water tube boilers where low efficiency dust collectors are incorporated. Dust burdens similar to those of the shrouded radial, in Section
1.5.4 are acceptable.
Posted in Fans Ventilation A Practical Guide