Recirculation barrier for a heat transfer system

A heat exchange apparatus comprising:

• a generally upright radiator having air intake and air discharge faces;
• a rotatable axial flow, suction-type fan having a plurality of circumferentially spaced impeller blades extending radially from a hub and positioned on one side of said radiator adjacent said air discharge face for drawing air through said radiator axially in a direction from said air intake face to said air discharge face, said air flow through said radiator having a major velocity component parallel with respect to the rotational axis of the fan, each of said blades having an effective axial width AW measured axially along the rotational axis of the fan between a first plane and a second plane, said planes being axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan, said first and second planes extending radially, respectively, through a point on the leading edge of each of the blades at the tip portion thereof and through a point on the trailing edge of each of the blades at the tip portion thereof;
• shroud means having one axial end operatively connected to said radiator and encircling said fan, said shroud means being shaped and positioned with respect to said radiator and the blades of said fan whereby the major velocity component of the air stream discharged by the fan is in a direction perpendicular to the direction of the major velocity component of the air stream entering the air intake face and flowing through said radiator, the axial end of said shroud means remote from said axial end operatively connected to said radiator being defined by an annular, radially outwardly extending flat portion lying substantially in a plane disposed perpendicular to the rotational axis of said fan, one of said first and second planes being axially spaced from and on either axial side of the plane containing said annular radially outwardly extending flat portion of said shroud means a distance of 12 percent or less of AW;
• and
• means axially positioned on the side of said fan opposite said radiator for obstructing flow of air axially through the fan at the hub region thereof in an axial direction opposite the direction of said major velocity component of air flow through said radiator, said means lying substantially in a plane spaced and substantially parallel with respect to said plane in which said flat portion of said shroud means lies.

A heat exchange apparatus comprising:

• a heat exchange means having front and rear faces;
• a shroud means including a forward section having forwardmost edge means arranged to encircle said rear face of said heat exchange means, and a rear exit shroud means having forwardmost edge means joined to rearwardmost edge means of said forward section, said exit shroud means including, in successive sections, a generally cylindrical, axially extending throat section, an annular, radially and axially extending, curved section, and an annular, generally radially extending flat portion;
• a rotatable axial flow, suction-type fan encircled by said rear exit shroud means having a plurality of circumferentially spaced impeller blades extending radially from a hub, each of said impeller blades having an effective axial width AW measured axially along the rotational axis of the fan between a first plane and a second plane, said planes being axially spaced and parallel with respect to each other and disposed substantially normal to the rotational axis of the fan, said first and second planes extending radially, respectively, through a point on the leading edge of each of the impeller blades at the tip region thereof and through a point on each of the trailing edges of the impeller blades also at the tip region thereof, said second plane being axially spaced from and on either axial side of a plane containing said annular, generally radially extending flat portion of said exit shroud means a distance of 12 percent or less of AW, and the following relationships exist:
• RF=AW/3 plus or minus 12 percent of AW, CF=AW/3 plus or minus 12 percent of AW, and R=2AW/3 plus or minus 12 percent of AW, where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvature of the radial curved section;
• and
• air recirculation barrier means axially spaced rearwardly of said second plane a predetermined distance less than one half of the diameter of said fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of said fan hub when said fan is rotated, said barrier means lying substantially in a plane spaced and substantially parallel with respect to said second plane.

A heat exchange apparatus comprising:

• the heat exchange means having front and rear faces;
• a shroud means including a forward section having forwardmost edge means arranged to encircle said rear face of said heat exchange means, and a rear exit shroud means having forwardmost means joined to rearwardmost edge means of said forward section, said exit shroud means including, in successive sections, a generally cylindrical, axially extending throat section, an annular radially and axially extending, curved section, and an annular, generally radially extending flat portion;
• a rotatable, axial flow, suction-type fan encircled by said rear exit shroud means having a plurality of circumferentially spaced impeller blades extending radially from a hub, each of said impeller blades having an effective axial width AW measured axially along the rotational axis of the fan between a first plane and a second plane, said planes being axially spaced and parallel with respect to each other and disposed substantially normal to the totational axis of the fan, said first and second planes extending radially, respectively, through a point on each of the leading edges of the impeller blades at the radial tip region thereof and through a point on each of the trailing edges of the impeller blades also at the radial tip region thereof, said second plane being axially spaced from and on either axial side of a plane containing said annular, generally radially extending flat portion of said exit shroud means a distance of 12 percent or less of AW, and the following relationships exist:
• RF=AW/3 plus or minus 12 percent of AW, CF=AW/3 plus or minus 12 percent of AW, and R=2AW/3 plus or minus 12 percent of AW where RF is the radial length of the radially extending flat portion, CF is the axial length of the cylindrical throat section, and R is the radius of curvature of the radial curved section;
• and
• air recirculation barrier means axially spaced rearwardly of said second plane a predetermined distance less than one half of the diameter of said fan for obstructing axial flow of air in a forward direction from the region axially rearwardly of said fan hub when said fan is rotated,
• said air recirculation barrier means being generally in a form of a flat and substantially imperforate disk, said disk lying substantially in a radial plane spaced and parallel with respect to said second plane.