Forward-Curved Blade Blowers

Centraugal Blowers These blowers have air or gases entering in the axial direction and being discharged in the radial direction. These blowers have 3 tvpes of blades, radial or straight blades, forward curved blades, and backward cui ved blades (Figs. 10-69-10-71). 

Forward-Curved Blade Blowers These blowers discharge the gas at a very high velocity. The pressure supplied by this blower is lower than that produced in the other two blade characteristics. The number of blades in such a rotor can be large—up to 50 blades—and the speed is high—usually 3600-1800 rpm in 60-cycle countries and 3000-1500 rpm in 50-cycle countries. 

Radial blade blowers as seen in Fig. 10-68 are usually used in large-diameter or high-temperature applications. The blades being radial in direction have very low stresses as compared to the backward or forward curve blades. The rotors have anywhere between 4 to 12 blades and usually operate at low speeds. These fans are used in exhaust work especially for gases at high temperature and with suspensions in the flow stream. 

Backward-Curved Blade Blowers These blowers are used when a higher discharge pressure is needed. It is used over a wide range of applications. Both the forward and backward curved blades do have much higher stresses than the radial bladed blower. 

Figure 9.12 Forward curved and backward curved blades on a centrifugal blower.

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