Air handling unit and fan therefor

Abstract

The present disclosure provides a fan including a hub and multiple fan blades coupled to the hub and located circumferentially along the hub. Each fan blade extends between a root and a tip edge thereof and includes a first portion inclined at a first predefined angle with respect to the hub. The first portion induces an axial flow of air. The fan blade also includes a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade. The second portion is embodied as an airfoil defining an angle of attack to induce a radial inward flow of air. A radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion.

What is claimed is: 
     
         1 . A fan comprising:
 a hub configured to rotate about an axis;   a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising:
 a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and 
 a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. 
   
     
     
         2 . The fan of  claim 1 , wherein a portion of the leading edge segment of the second portion extends perpendicular with respect to the first portion of the fan blade. 
     
     
         3 . The fan of  claim 1 , wherein the leading edge segment of the second portion is bent inward towards the hub to define the angle of attack of the fan blade. 
     
     
         4 . The fan of  claim 3 , wherein a distance between the trailing edge segment of the second portion and a center of the hub is less than a distance between the leading edge segment of the second portion and the center of the hub. 
     
     
         5 . The fan of  claim 3 , wherein the angle of attack at the tip edge of the fan blade is lower than the angle of attack at a base of the second portion, with respect to a radial direction of the fan blade. 
     
     
         6 . The fan of  claim 3 , wherein the angle of attack of the fan blade is in a range of about 3 degrees to about 15 degrees. 
     
     
         7 . The fan of  claim 1 , wherein a span of the second portion is less than a span of the first portion of the fan blade. 
     
     
         8 . The fan of  claim 1 , wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air. 
     
     
         9 . The fan of  claim 1 , wherein the first portion of the fan blade in non-planar. 
     
     
         10 . The fan of  claim 1 , wherein each of the plurality of fan blades is made of one of plastic, metal, and composite material. 
     
     
         11 . The fan of  claim 1 , wherein each of the plurality of fan blades is a swept blade. 
     
     
         12 . An air handling unit comprising:
 a cabinet;   a motor housed within the cabinet; and   a fan operably coupled to the motor, the fan configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet, the fan comprising:
 a hub coupled to a shaft of the motor and configured to rotate about an axis; and 
 a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising:
 a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and 
 a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. 
 
   
     
     
         13 . The air handling unit of  claim 12  further comprising a plurality of refrigerant tubes extending along a periphery of the cabinet, wherein the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes. 
     
     
         14 . The air handling unit of  claim 12 , wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air. 
     
     
         15 . The air handling unit of  claim 12 , wherein a portion of the leading edge segment of the second portion of the fan blade extends perpendicular with respect to the first portion of the fan blade. 
     
     
         16 . The air handling unit of  claim 12 , wherein the leading edge segment of the second portion of the fan blade is bent inward towards the hub to define the angle of attack of the fan blade. 
     
     
         17 . An air handling unit comprising:
 a cabinet;   a motor housed within the cabinet;   a bell mouth extending from the cabinet in a direction inward along a longitudinal axis of the cabinet, the bell mouth configured to partially conceal the motor in a transverse direction of the cabinet; and   a fan operably coupled to the motor, the fan configured to allow a uniform inflow of air at an upper portion of the cabinet and direct the air from inside of the cabinet to outside of the cabinet through the bell mouth, the fan comprising:
 a hub coupled to a shaft of the motor and configured to rotate about the longitudinal axis of the cabinet; and 
 a plurality of fan blades coupled to the hub and located circumferentially along the hub, wherein each fan blade extends between a root and a tip edge, the fan blade comprising:
 a first portion inclined at a first predefined angle with respect to the hub, the first portion configured to induce an axial flow of air; and 
 a second portion extending from the first portion and between a leading edge and a trailing edge of the fan blade, the second portion configured as an airfoil defining an angle of attack to induce a radial inward flow of air, wherein the second portion is partially concealed by the bell mouth in the transverse direction of the cabinet, and wherein a radius of curvature of a trailing edge segment of the second portion is less than a radius of curvature of a leading edge segment of the second portion. 
 
   
     
     
         18 . The air handling unit of  claim 17 , wherein the induced radial inward flow of air is in a range of about 5% to about 10% of the induced axial flow of air. 
     
     
         19 . The air handling unit of  claim 17  further comprising a plurality of refrigerant tubes extending along a periphery of the cabinet, wherein the fan is configured to induce airflow over the plurality of refrigerant tubes to achieve heat exchange with respect to the plurality of refrigerant tubes. 
     
     
         20 . The air handling unit of  claim 17  further comprising a fan guard coupled to an outlet of the bell mouth.