EP0078660A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Efficient axial flow impeller for mixing
Assignee: SPX Technologies Inc
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Filing: 1982-10-27
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Granted: —
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Expires: 2002-10-27
Abstract
Abstract © The mixing of liquids and liquid suspensions in vessels is obtained by a mixing impeller mounted on a shaft and rotated by a drive which delivers selected speed and torque. The torque and power needed to obtain given flow is minimized by a low-cost impeller having a plurality of blades, each formed from a plate of constant thickness except for a leading edge of rounded profile. Each blade has camber which decreases from the tip to the base thereof. The base can be flat to facilitate the attachment of the blades to the shaft. The blades are oriented and twisted to be at the threshold for flow separating along the width of the blades from the leading to the trailing edge thereof, thereby providing maximum flow in the axial direction before the onset of said separation. The orientation and twist of the blades provides a generally constant angle of attack along the entire blade from tip to base and the planform of the blade provides for uniform loading, stability and minimization fo fluid forces which tend to bend the shaft.
Inventors
- 👤 Ronald J. Weetman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 01:32
CPC Classifications
C; C02; C02F; C02F3/00; C02F3/02; C02F3/12; C02F3/1278; C02F3/1284; B; B01; B01F; B01F27/00; B01F27/05; B01F27/11; B01F27/113; B01F27/80; B01F27/91; Y; Y02; Y02W; Y02W10/00; Y02W10/10; Y10; Y10S; Y10S416/00; Y10S416/02; Y10S416/05
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
152 words
For use in mixing a liquid or a liquid suspension medium contained in a vessel, impeller apparatus which comprises an impeller, a shaft having an axis mounting said impeller in said vessel below the level of said medium, a plurality of blades mounted on said shaft for rotation about said axis, each of said blades being formed of a plate of constant thickness except for a rounded profile along its leading edge and camber which decreases from the tip to a region adjacent to the base of said blade, each blade also having a geometric pitch angle which increases from the tip to the base thereof and which is at the threshold for flow separation from the surface of said blade along the width thereof from the leading to the trailing edge thereof, such that maximum flow in the direction axially of said shaft is obtained before the onset of said separation.
Claim 2
Dependent Claim
152 words
For use in mixing a liquid or a liquid suspension medium contained in a vessel, impeller apparatus which comprises an impeller, a shaft having an axis mounting said impeller in said vessel below the level of said medium, a plurality of blades mounted on said shaft for rotation about said axis, each of said blades being formed of a plate of constant thickness except for a rounded profile along its leading edge and camber which decreases from the tip to a region adjacent to the base of said blade, each blade also having a geometric pitch angle which increases from the tip to the base thereof and which is at the threshold for flow separation from the surface of said blade along the width thereof from the leading to the trailing edge thereof, such that maximum flow in the direction axially of said shaft is obtained before the onset of said separation.
Claim 3
Dependent Claim
44 words
The impeller apparatus according to claim 1 wherein the variation of said geometric pitch angle from tip to base of each blade is such as to define a generally constant angle of attack in a direction radially of said shaft axis along said blade.
Claim 4
Dependent Claim
47 words
The impeller apparatus according to claim 2 wherein said geometric pitch angle at the tip of said blades is in a range from about 12° to 32° and increases along the length of each blade from the tip to the base thereof by about 16 0 .
Claim 5
Dependent Claim
32 words
The impeller apparatus according to any preceding claim wherein said camber varies from the tip to said base region of each of said blades within a range of about 8% to 0%.
Claim 6
Dependent Claim
50 words
The impeller apparatus according to claim 4 wherein at a section through said blade perpendicular to a diameter line extending through said shaft at 0.7 D, where D is measured along said diameter to a point intersected by the tip of said blade, said camber is between 4% and 8%.
Claim 7
Dependent Claim
28 words
The impeller apparatus according to claim 5 wherein the thickness of said blade is about 6% to 10% of the chord thereof in said section at 0.7 D.
Claim 8
Dependent Claim
89 words
The impeller apparatus as set forth in any preceding claim wherein each of said blades is mounted on said shaft such that the intersection of said tip and said leading edge is along a diameter through said shaft, and the arrangement furthermore is such that a section along a perpendicular to said diameter at a point 0.7 D, where D is the distance along said diameter to said intersection from said shaft axis, intersects said diameter at a load point where the center of forces on-said blade is located.
Claim 9
Dependent Claim
52 words
The impeller apparatus according to claim 7 wherein said leading edge is swept back from said base to said tip, such that said load point is at a point in said section at 0.7 D which is one quarter of the length of the chord at such section from the leading edge.
Claim 10
Dependent Claim
25 words
The impeller apparatus according to claim 7 or 8 wherein each of said blades has a planform which is substantially as shown in FIG. 8.
Claim 11
Dependent Claim
39 words
The impeller apparatus according to any preceding claim wherein the trailing edge of each of said blades, at least in a portion thereof from said tip to said base region, is in a plane perpendicular to said shaft axis.
Claim 12
Dependent Claim
19 words
The impeller apparatus as set forth in any preceding claim further comprising flow stabilizer means attached to said impeller.
Claim 13
Dependent Claim
23 words
The impeller apparatus according to claim 11 wherein said stabilizer means comprises a fin attached to the tip of each of said blades.
Claim 14
Dependent Claim
39 words
The impeller apparatus as set forth in claim 11 or 12 wherein said stabilizer means comprises a cylindrical tube attached to the base region of said blades below the trailing edges thereof co-axially with the axis of said shaft.
Claim 15
Dependent Claim
55 words
The impeller apparatus according to any preceding claim wherein another impeller is mounted on said shaft below said first-named impeller and has a plurality of blades each disposed at a geometric pitch angle beyond the angle for separation of flow in said medium whereby to impart shear forces in a radial direction in said medium.
Claim 16
Dependent Claim
42 words
The impeller apparatus as set forth in any preceding claim mounted in a tank such that it is located at a distance from the bottom of said tank in a range of about two to four times the diameter of the impeller.
Claim 17
Dependent Claim
57 words
An impeller for liquid or liquid suspension mixing comprising a plurality of blades rotatable about an axis, each being a curved plate airfoil and having a leading edge with a rounded profile, said blades each being oriented to define geometric pitch angles at the threshold of flow separation for maxiumum flow in the direction of said axis.
Claim 18
Dependent Claim
57 words
An impeller for liquid or liquid suspension mixing comprising a plurality of blades rotatable about an axis, each being a curved plate airfoil and having a leading edge with a rounded profile, said blades each being oriented to define geometric pitch angles at the threshold of flow separation for maxiumum flow in the direction of said axis.
References Cited (Backward Citations)
No citation records indexed.
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