Fan for cooling tower

Abstract

An industrial fan for a cooling tower comprises a disc-shaped hub and a plurality of blades radially connected to the disc of the hub by means of a stud, provided on one end of each said blade, and a flange provided on one face of the hub and into which the stud of the blade is inserted with a blade angle for generating an axial air flow, each blade has such an aerodynamic profile that the pressure difference between pressure and suction faces is lower at the blade foot than at the middle of the blade chord and is higher at the blade head than at the middle of the blade chord, and it is provided a junction means for blocking the air recirculation between the pressure and suction faces at the blade foot.

1 . Industrial fan for a cooling tower, comprising a disc-shaped hub and a plurality of blades radially connected to the disc of said hub by means of a stud, provided on one end of each said blade, and a flange provided on one face of the hub and into which said stud of said blade is inserted with a blade angle for generating an axial air flow, characterized in that each said blade has such an aerodynamic profile that, over a region corresponding to 30% of the length of said blade from the blade foot, the pressure difference Δ(P 1 ) between pressure and suction sides edges is comprised between 65% and 75% of the pressure difference (ΔPC) between the pressure and suction faces at the middle of the blade chord and that, over a region corresponding to 30% of the length of said blade from the blade head, the pressure difference (ΔP 2 ) between the pressure and suction edges is comprised between 125% and 135% of the pressure difference (ΔPC) between the pressure and suction faces at the middle of the blade chord, and in that it is provided a junction means for blocking the air recirculation between the pressure and suction faces at the blade foot. 
     
     
         2 . Fan according to  claim 1 , characterized in that said junction means is a fin which extends along the pressure and suction faces perpendicularly to the surface of said blade at the foot of said blade. 
     
     
         3 . Fan according to  claim 1 , characterized in that said flange comprises at least one jaw. 
     
     
         4 . Fan according to  claim 1 , characterized in that it comprises at least three blades. 
     
     
         5 . Fan according to  claim 1 , characterized in that the envelope of said blades is made out of composite materials. 
     
     
         6 . Fan according to  claim 1 , characterized in that the envelope of said blades is in the form of a pre-shapeable fabric with reinforcing fibers. 
     
     
         7 . Fan according to  claim 6 , characterized in that said reinforcing fiber is made out of glass fabric. 
     
     
         8 . Fan according to  claim 5 , characterized in that the envelope of said blades is impregnated with a two-component material such as polyester, vinyl esters, epoxies or the like. 
     
     
         9 . Fan according to  claim 5 , characterized in that its coating is injection molded. 
     
     
         10 . Fan according to  claim 1 , characterized in that said blades are hollow and stiffened by filling their cavity with a lightweight material such as polyurethane foam. 
     
     
         11 . Fan according to  claim 1 , characterized in that said blades have a pressure face which has a flat surface region for receiving an inclinometer and in that the pitch between the angles of inclination of said blades is adjusted with an accuracy of + or −0.1°. 
     
     
         12 . Fan according to  claim 1 , characterized in that each of said blades ( 6 ) has a blade angle which is adjustable between 25° and 45°. 
     
     
         13 . Fan according to  claim 1 , characterized in that the position of each of said blades radially connected to said hub disc is adjustable by means of a screw. 
     
     
         14 . Fan according to  claim 1 , characterized in that said junction means has a rotational shape and is combined with sealing elements such as elastomeric or silicone seals. 
     
     
         15 . Air heat exchanger provided with finned tubes characterized in that it comprises a fan according to  claim 1 .