US2956736A - Centrifugal fans - Google Patents

Centrifugal fans Download PDF

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US2956736A
US2956736A US813317A US81331759A US2956736A US 2956736 A US2956736 A US 2956736A US 813317 A US813317 A US 813317A US 81331759 A US81331759 A US 81331759A US 2956736 A US2956736 A US 2956736A
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fan
housing
blades
end portion
airfoil
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US813317A
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Jr Mayer Mayer
James I Kotter
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
    • F04D29/422—Discharge tongues

Definitions

  • This invention relates to centrifugal fans.
  • a centrifugal fan comprises a spiral fan housing provided with an outlet port, a fan wheel rotatably mounted in said housing and provided with fan blades, and a point of cutoff where the flow of air is discharged through said outlet port.
  • air enters the fan housing through an air inlet opening and is thrust between the fan blades.
  • the blades propel the air through the housing past the point of cutoff where the air is discharged through the outlet port.
  • Objectionable noise is created at the point of cutoff and, in order to minimize this noise, it is standard practice to utilize a fan wheel of such diameter that the free ends of each of the fan blades clears the point of cutoff by an appreciable distance.
  • the instant invention has as its object the provision of a centrifugal fan having greatly decreased noise at the point of cutoff, as well as high fan efiiciency.
  • centrifugal fan in which a specially shaped end portion of the housing wall having a cambered surface of particularly critical dimensions, as will be described hereinafter, and having a rounded leading edge which serves as a point of cutoff, permits spacing of the free outer ends of the fan blades of the fan wheel so that they run close to said leading edge.
  • Fig. 1 is a cross-section of a centrifugal fan illustrating the invention.
  • Fig. 2 is an enlarged view of the specially shaped end portion of the housing wall.
  • Fig. 1 illustrates a centrifugal fan having a fan housing comprising a peripheral wall 11.
  • a fan wheel 12 having radial blades 13 with free outer ends, is rotatably mounted in the housing on a shaft 14 driven by a power source not shown.
  • the housing wall 11 has an airfoil-shaped end portion 20 extending in an upstream direction, that is, in a direction opposed to the direction of rotation of blades 13.
  • This airfoil-shaped end portion is provided with a rounded leading free edge 21 having close running Patented Oct. 18, 1960 clearance with the free outer ends of the blades 13 to give high fan efliciency.
  • the airfoil-shaped end portion is joined at its other edge to the remainder 22 of housing wall 11 to form a line of jointure at 23, the said remainder wall portion 22 being spaced radially outwardly from the free outer ends of the blades 13 and encircling the fan wheel in a spiral formation.
  • the housing is provided with an outlet port for the egress of air, this outlet port being defined as the opening included between the leading edge 21 of the airfoil-shaped end portion 20 and the spiral wall of the housing opposite thereto.
  • the outlet port communicates with a duct 25 to carry away the discharged air.
  • the airfoil-shaped end portion 20 also has a cambered surface on its side 30 remote from the fan wheel, as shown in Fig. 1, while its other side 31 may have a surface of any shape. As illustrated in Fig. 1, side 31 has a surface contoured to the shape of the spiral housing.
  • the dimensions of the cambered surface of side 30 are such that A ranges from .10 to .20 of C and X ranges from .20 to .45 of C, wherein C is the distance from leading edge 21 to the line of jointure at 23 of the airfoilshaped end portion 20 to the remainder 22 of the spiral wall of the housing, A is the perpendicular distance from the highest point 35 of said cambered surface of side 30 to a base line 36 drawn from said leading edge to said line of jointure at 23, and X is the distance from said highest point 35 of said cambered surface to a line 37 drawn perpendicular through said leading edge to said base line 36.
  • the dimensions of the cambered surface of side 30 are such that A is inch, X is inch, C is 2% inches, and the overall diameter of the fan wheel is 10 inches.
  • C may range from 1 /8 inches to 3% inches for a fan having an overall diameter of 10 inches.
  • the fan blades 13 propel the air through the housing past the leading edge 21 of the airfoil-shaped end portion 20.
  • the latter by virtue of its critical shape, functions to decrease the noise of the moving air as it is discharged through the outlet port, with the fan operating at high efficiency.
  • the leading edge serves as the point of cutoff in the housing.
  • a centrifugal fan comprising a housing, a fan wheel rotatably mounted in the housing and having radial blades with free outer ends, said housing comprising a peripheral wall having an airfoil-shaped end portion extending in an upstream direction and being provided with a rounded leading free edge having a close running clearance with the free outer ends of said blades to give high fan efficiency, said airfoil-shaped end portion being joined at its other edge to the remainder of said wall, said remainder wall portion being spaced radially outwardly from said free outer ends of the blades and encircling the fan wheel in a spiral formation, an outlet port for the housing, said outlet port being defined as the opening included between said leading free edge of the airfoil-shaped end portion and the spiral wall of the housing opposite thereto, said airfoil-shaped end portion having, in addition to its rounded leading edge, a cambered surface on its side remote from the fan wheel in which A ranges from .10 to .20 of C and X

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Description

Oct. 18, 1960 MAYER JR" ETAL 2,956,736
CENTRIFUGAL FANS Filed May 14, 1959 INVENTORS MAYER MAYER, Jr. JAMES l. KOTTER ATTORNEYS United States Patent CENTRIFUGAL FANS Mayer Mayer, Jr., New Orleans, and James I. Kotter, Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture Filed May 14, 1959, Ser. No. 813,317
1 Claim. (Cl. 230-127) (Granted under Title 35, US. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sub-licenses for such purposes, is hereby granted to the Government of the United States of America.
This invention relates to centrifugal fans.
A centrifugal fan comprises a spiral fan housing provided with an outlet port, a fan wheel rotatably mounted in said housing and provided with fan blades, and a point of cutoff where the flow of air is discharged through said outlet port. In the operation of such a fan, air enters the fan housing through an air inlet opening and is thrust between the fan blades. As the fan wheel rotates, the blades propel the air through the housing past the point of cutoff where the air is discharged through the outlet port.
Objectionable noise is created at the point of cutoff and, in order to minimize this noise, it is standard practice to utilize a fan wheel of such diameter that the free ends of each of the fan blades clears the point of cutoff by an appreciable distance.
However, while such positioning of the blades tends to reduce noise it also detrimentally influences fan efficiency and makes it necessary to utilize a fan of greater size than would be required if the free ends of the blades ran close to the point of cutoff.
The instant invention has as its object the provision of a centrifugal fan having greatly decreased noise at the point of cutoff, as well as high fan efiiciency.
These objects are accomplished by providing a centrifugal fan in which a specially shaped end portion of the housing wall having a cambered surface of particularly critical dimensions, as will be described hereinafter, and having a rounded leading edge which serves as a point of cutoff, permits spacing of the free outer ends of the fan blades of the fan wheel so that they run close to said leading edge.
In the accompanying drawing,
Fig. 1 is a cross-section of a centrifugal fan illustrating the invention; and
Fig. 2 is an enlarged view of the specially shaped end portion of the housing wall.
Referring to the drawing,
Fig. 1 illustrates a centrifugal fan having a fan housing comprising a peripheral wall 11. A fan wheel 12, having radial blades 13 with free outer ends, is rotatably mounted in the housing on a shaft 14 driven by a power source not shown.
The housing wall 11 has an airfoil-shaped end portion 20 extending in an upstream direction, that is, in a direction opposed to the direction of rotation of blades 13. This airfoil-shaped end portion is provided with a rounded leading free edge 21 having close running Patented Oct. 18, 1960 clearance with the free outer ends of the blades 13 to give high fan efliciency. The airfoil-shaped end portion is joined at its other edge to the remainder 22 of housing wall 11 to form a line of jointure at 23, the said remainder wall portion 22 being spaced radially outwardly from the free outer ends of the blades 13 and encircling the fan wheel in a spiral formation.
As a result of this structure, the housing is provided with an outlet port for the egress of air, this outlet port being defined as the opening included between the leading edge 21 of the airfoil-shaped end portion 20 and the spiral wall of the housing opposite thereto. The outlet port communicates with a duct 25 to carry away the discharged air.
The airfoil-shaped end portion 20 also has a cambered surface on its side 30 remote from the fan wheel, as shown in Fig. 1, while its other side 31 may have a surface of any shape. As illustrated in Fig. 1, side 31 has a surface contoured to the shape of the spiral housing.
The dimensions of the cambered surface of side 30 are such that A ranges from .10 to .20 of C and X ranges from .20 to .45 of C, wherein C is the distance from leading edge 21 to the line of jointure at 23 of the airfoilshaped end portion 20 to the remainder 22 of the spiral wall of the housing, A is the perpendicular distance from the highest point 35 of said cambered surface of side 30 to a base line 36 drawn from said leading edge to said line of jointure at 23, and X is the distance from said highest point 35 of said cambered surface to a line 37 drawn perpendicular through said leading edge to said base line 36.
As a specific example of a highly satisfactory fan, the dimensions of the cambered surface of side 30 are such that A is inch, X is inch, C is 2% inches, and the overall diameter of the fan wheel is 10 inches. In this example, C may range from 1 /8 inches to 3% inches for a fan having an overall diameter of 10 inches.
In operation, air enters the housing through air inlet opening 40. As the fan wheel rotates, the fan blades 13 propel the air through the housing past the leading edge 21 of the airfoil-shaped end portion 20. The latter, by virtue of its critical shape, functions to decrease the noise of the moving air as it is discharged through the outlet port, with the fan operating at high efficiency. Thus, in effect, the leading edge serves as the point of cutoff in the housing.
Having thus described the invention, what is claimed A centrifugal fan comprising a housing, a fan wheel rotatably mounted in the housing and having radial blades with free outer ends, said housing comprising a peripheral wall having an airfoil-shaped end portion extending in an upstream direction and being provided with a rounded leading free edge having a close running clearance with the free outer ends of said blades to give high fan efficiency, said airfoil-shaped end portion being joined at its other edge to the remainder of said wall, said remainder wall portion being spaced radially outwardly from said free outer ends of the blades and encircling the fan wheel in a spiral formation, an outlet port for the housing, said outlet port being defined as the opening included between said leading free edge of the airfoil-shaped end portion and the spiral wall of the housing opposite thereto, said airfoil-shaped end portion having, in addition to its rounded leading edge, a cambered surface on its side remote from the fan wheel in which A ranges from .10 to .20 of C and X ranges from .20 to .45 of C, wherein C is the distance from said lead- 3 4 ing edge to the line of jointure of the airfoil-shaped and References Cited in the file of this patent portion to the remainder of the spiral wall of the housing, UNITED STATES PATENTS A is the perpendicular distance from the highest point 2 596 646 Buchi May 13 1952 of said cambered surface to a base line drawn from said 5 2:596:647 Buchi May 1952 leading edge to said line of jointure, and X is the distance from said highest point of said cambered surface to a FOREIGN PATENTS line drawn perpendicular through said leading edge to 278,711 Switzerland Feb. 1, 1952 said base line. 1,038,819 France May 13, 1953
US813317A 1959-05-14 1959-05-14 Centrifugal fans Expired - Lifetime US2956736A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3687360A (en) * 1969-11-19 1972-08-29 Beloit Corp Noise suppressing baffle discharge exit
DE2705329A1 (en) * 1977-02-09 1978-08-10 Hanning Elektro Werke Dishwasher or washing machine water discharge pump - has radially outer wall of discharge spigot offset outwardly from housing to provide suction to reduce cavitation
US20030039541A1 (en) * 2001-08-20 2003-02-27 Xerox Corporation Blower noise reducing device and a blower having same
US20140314544A1 (en) * 2011-11-15 2014-10-23 Koninklijke Philips N.V. Devices and methods for reducing noise in a blower housing

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH278711A (en) * 1949-09-30 1951-10-31 Wegmann Ernst Fan with spiral casing.
US2596646A (en) * 1946-01-19 1952-05-13 Buchi Alfred Outlet guiding arrangement
US2596647A (en) * 1946-03-06 1952-05-13 Buchi Alfred Outlet guiding arrangement
FR1038819A (en) * 1951-02-15 1953-10-01 Oerlikon Maschf Centrifugal fan

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2596646A (en) * 1946-01-19 1952-05-13 Buchi Alfred Outlet guiding arrangement
US2596647A (en) * 1946-03-06 1952-05-13 Buchi Alfred Outlet guiding arrangement
CH278711A (en) * 1949-09-30 1951-10-31 Wegmann Ernst Fan with spiral casing.
FR1038819A (en) * 1951-02-15 1953-10-01 Oerlikon Maschf Centrifugal fan

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3687360A (en) * 1969-11-19 1972-08-29 Beloit Corp Noise suppressing baffle discharge exit
DE2705329A1 (en) * 1977-02-09 1978-08-10 Hanning Elektro Werke Dishwasher or washing machine water discharge pump - has radially outer wall of discharge spigot offset outwardly from housing to provide suction to reduce cavitation
US20030039541A1 (en) * 2001-08-20 2003-02-27 Xerox Corporation Blower noise reducing device and a blower having same
US20140314544A1 (en) * 2011-11-15 2014-10-23 Koninklijke Philips N.V. Devices and methods for reducing noise in a blower housing
US9765796B2 (en) * 2011-11-15 2017-09-19 Koninklijke Philips N. V. Devices and methods for reducing noise in a blower housing

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