US4012166A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Supersonic shock wave compressor diffuser with circular arc channels
Assignee: Deere and Co
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Filing: 1974-12-04
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Granted: 1977-03-15
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Expires: 1994-12-04
Abstract
Abstract A supersonic shock wave compressor diffuser forms a concentric annulus about a radial compressor having a central axis. Circular channels diverge with an increasing divergence angle as they extend along an arcuate longitudinal center line from an inner circumference very near the periphery of the compressor to the outer circumference of the diffuser. Shock waves may occur within the channels near the inner circumference of the diffuser or may occur within a vaneless diffusion space adjacent the periphery of the compressor and provide efficient energy conversion and reduce the velocity substantially below MACH 1 to further improve the efficiency of the subsonic diffusion downstream therefrom. A logarithmic spiral is approximated by a circular arc subtended by the channel longitudinal axes to permit recovery of angular momentum while the circular cross section of the channels permits recovery of swirl velocity energy. The required diameter of the outer circumference of the diffuser is reduced by using the shock waves to greatly reduce gas velocity within a short distance, by the curvature of the channels and by the angle of incidence of the longitudinal channel axes.
Inventors
- 👤 Merle L. Kaesser
- 👤 Homer J. Wood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:10
CPC Classifications
F; F04; F04D; F04D29/00; F04D29/40; F04D29/42; F04D29/44; F04D29/441; F05; F05B; F05B2200/00; F05B2200/20; F05B2200/23; F05D; F05D2250/00; F05D2250/50; F05D2250/52
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
179 words
A diffuser for use with a centrifugal compressor comprising first and second body halves mating along a central plane to define an annular diffuser body having a central axis, an inner circumference adapted for concentric disposition about the periphery of a centrifugal compressor in close proximity thereto, and an outer circumference, said diffuser body having a plurality of curved diffusion channels defined therein which extend between the inner and outer circumference and which curve toward a direction of a tangential velocity component of gases entering the diffuser channels at the inner circumference, the diffusion channels having a cross section perpendicular to a central longitudinal axis therealong which is at least generally circular and a divergence angle which increases with distance from the inner circumference without sharp transitions in the diffusion channel walls to provide each channel with a diameter that increases at an increasing rate as distance from the inner circumference increases, adjacent diffusion channels intersecting near the inner circumference along a sharp, generally elliptical edge which is in close proximity to the outer circumference of a centrifugal compressor.
Claim 2
Dependent Claim
179 words
A diffuser for use with a centrifugal compressor comprising first and second body halves mating along a central plane to define an annular diffuser body having a central axis, an inner circumference adapted for concentric disposition about the periphery of a centrifugal compressor in close proximity thereto, and an outer circumference, said diffuser body having a plurality of curved diffusion channels defined therein which extend between the inner and outer circumference and which curve toward a direction of a tangential velocity component of gases entering the diffuser channels at the inner circumference, the diffusion channels having a cross section perpendicular to a central longitudinal axis therealong which is at least generally circular and a divergence angle which increases with distance from the inner circumference without sharp transitions in the diffusion channel walls to provide each channel with a diameter that increases at an increasing rate as distance from the inner circumference increases, adjacent diffusion channels intersecting near the inner circumference along a sharp, generally elliptical edge which is in close proximity to the outer circumference of a centrifugal compressor.
Claim 3
Dependent Claim
44 words
The diffuser according to claim 1 above, wherein the maximum diameter of the vaneless diffusion space between the outer circumference of a compressor and inlets to the diffusion channels is not more than 1.05 times the diameter of the inner circumference of the diffuser.
Claim 4
Dependent Claim
46 words
The diffuser according to claim 1 above, wherein the maximum diameter of the vaneless diffusion space between the outer circumference of a compressor rotor and inlets to the diffuser channels is not more than 1.06 times the diameter of the outer circumference of the compressor rotor.
Claim 5
Dependent Claim
68 words
The diffuser according to claim 1 above, wherein the diffuser is for use with a centrifugal compressor rotor from which compressed gases exit an outer periphery of the compressor rotor at supersonic velocities at normal operating speeds, and wherein inlets to the diffusion channels are located sufficiently close to the periphery of the compressor rotor that shock waves occur adjacent inlets to the channels under normal operating conditions.
Claim 6
Dependent Claim
28 words
The diffuser according to claim 1 wherein each diffusion channel has a longitudinal central axis extending therealong and is circular in cross section normal to the longitudinal axis.
Claim 7
Dependent Claim
56 words
The diffuser according to claim 5 above, wherein the diffuser is for use with a compressor rotor having an outer circumference which is 6 inches in diameter, wherein the diffuser has an outer circumference which is not more than 12 inches in diameter, and wherein there are between 20 and 24 diffusion channels within the diffuser.
Claim 8
Dependent Claim
71 words
The diffuser according to claim 6 above, wherein there are 24 channels and wherein each diffusion channel has a diameter of approximately 0.28 inch at the inlet thereof and a diameter of approximately 0.63 inch at a radially outwardmost point along the longitudinal axis thereof at which a cross section perpendicular to the longitudinal axis lies entirely within a circle about the axis of rotation having a radius of 12 inches.
Claim 9
Dependent Claim
24 words
The diffuser according to claim 6 above, wherein the longitudinal axis of each channel approximates a logarithmic spiral path by following a circular arc.
Claim 10
Dependent Claim
74 words
The diffuser according to claim 8 above, wherein the circular arc has a radius of 15 inches and wherein the longitudinal axis of each diffusion channel intersects an inner circumference of the diffuser at a reference point and wherein for each diffusion channel a tangent to the longitudinal axis at the reference point intersects a tangent to the inner circumferences of the diffuser at the reference point with an included acute angle of 15°.
Claim 11
Dependent Claim
202 words
A compressor diffuser for use with a supersonic, centrifugal compressor rotor which rotates within an outer circumference about an axis of rotation, the diffuser comprising an annular diffuser body having a plurality of circular cross-section diffusion channels defined therein, each of said channels intersecting with adjacent channels at inlet ends which are concentrically disposed about the outer circumference of a compressor rotor in close proximity thereto to permit a fluid passing through the compressor to approach the inlet end of each channel at a supersonic velocity with as high a mach number as possible and form a shock wave thereat, each of said channels extending along a longitudinal axis from an inlet end to an outlet end which is spaced radially outward from the inlet end, each of said channels having a first region in which the diameter increases at a first rate with respect to length along the longitudinal axis and each of said channels having a second region radially outward from the first region in which the diameter increases at a second rate greater than the first rate with respect to length along the longitudinal axis with channel walls being free of sharp transitions between the first and second regions.
Claim 12
Dependent Claim
202 words
A compressor diffuser for use with a supersonic, centrifugal compressor rotor which rotates within an outer circumference about an axis of rotation, the diffuser comprising an annular diffuser body having a plurality of circular cross-section diffusion channels defined therein, each of said channels intersecting with adjacent channels at inlet ends which are concentrically disposed about the outer circumference of a compressor rotor in close proximity thereto to permit a fluid passing through the compressor to approach the inlet end of each channel at a supersonic velocity with as high a mach number as possible and form a shock wave thereat, each of said channels extending along a longitudinal axis from an inlet end to an outlet end which is spaced radially outward from the inlet end, each of said channels having a first region in which the diameter increases at a first rate with respect to length along the longitudinal axis and each of said channels having a second region radially outward from the first region in which the diameter increases at a second rate greater than the first rate with respect to length along the longitudinal axis with channel walls being free of sharp transitions between the first and second regions.
Claim 13
Dependent Claim
62 words
The compressor according to claim 10 above, wherein the diameters of each channel approximately follows the relationship D = 1/2 K 1 L 2 + K 2 , where D is the channel diameter, L is channel length along the longitudinal axis from the inlet end, K 1 is a constant and K 2 is the channel diameter at the inlet end.
Claim 14
Dependent Claim
18 words
The compressor according to claim 11 above, wherein K 1 is approximately 0.053 inches per inch 2 .
Claim 15
Dependent Claim
31 words
The compressor diffuser according to claim 12 above, wherein the longitudinal axis of each channel extends along a circular arc which intersects said outer circumference at an angle of approximately 15°.
Claim 16
Dependent Claim
23 words
The compressor diffuser according to claim 12 above, wherein the longitudinal axes of all of the diffusion channels lie within a single plane.
Claim 17
Dependent Claim
69 words
The compressor diffuser according to claim 10 above, wherein the diffusion channels have a circular cross section normal to their longitudinal axis and wherein for each channel between an inlet end and a point along the longitudinal axis where the cross-sectional area is 5 times the cross-sectional area at the inlet end, the second derivative of the channel diameter with respect to arcuate longitudinal axis length is substantially constant.
Claim 18
Dependent Claim
20 words
The compressor diffuser according to claim 15 above, wherein said second derivative is approximately 0.014 inches per inch 2 .
Claim 19
Dependent Claim
50 words
The compressor diffuser according to claim 10 above, wherein the inlet of each channel is disposed sufficiently close to the periphery of the compressor that a shock wave occurs near the inlet and wherein gas velocity in the radially inward side of the shock wave is at least MACH 1.35.
Claim 20
Dependent Claim
185 words
A diffuser for receiving gases discharged from a circumference of a centrifugal compressor and increasing the static pressure thereof, the diffuser comprising an annulus extending about a central axis and having an inner circumference which fits closely about the periphery of a compressor wheel, an outer circumference radially spaced from the inner circumference, a pair of spaced opposing sides extending between the inner and outer circumferences, and a plurality of channels which are curvilinear in cross section extending between the inner and outer circumferences intermediate the opposing sides each channel having a smallest cross-sectional area adjacent the inner circumference and expanding substantially continuously and with an increasing divergence angle with increasing radial position relative to the central axis to a largest cross-sectional area at the outer circumference with smoothly blended transitions between changes in divergence, adjacent channels intersecting near the inner circumference along sharp edges which are disposed close to the circumference of the centrifugal compressor to induce a shock wave at an inlet to each channel near the sharp edges with a maximum mach number on the radially inward side of the shock wave.
Claim 21
Dependent Claim
185 words
A diffuser for receiving gases discharged from a circumference of a centrifugal compressor and increasing the static pressure thereof, the diffuser comprising an annulus extending about a central axis and having an inner circumference which fits closely about the periphery of a compressor wheel, an outer circumference radially spaced from the inner circumference, a pair of spaced opposing sides extending between the inner and outer circumferences, and a plurality of channels which are curvilinear in cross section extending between the inner and outer circumferences intermediate the opposing sides each channel having a smallest cross-sectional area adjacent the inner circumference and expanding substantially continuously and with an increasing divergence angle with increasing radial position relative to the central axis to a largest cross-sectional area at the outer circumference with smoothly blended transitions between changes in divergence, adjacent channels intersecting near the inner circumference along sharp edges which are disposed close to the circumference of the centrifugal compressor to induce a shock wave at an inlet to each channel near the sharp edges with a maximum mach number on the radially inward side of the shock wave.
Claim 22
Dependent Claim
37 words
The diffuser as set forth in claim 18 above, wherein the longitudinal central axis of each channel extends radially outward in circular arc having a radius greater than the radius of the outer circumference of the diffuser.
Claim 23
Dependent Claim
114 words
A compressor diffuser for use with a supersonic, centrifugal compressor rotor which rotates within an outer circumference about an axis of rotation, the diffuser comprising a diffuser body having a plurality of diffusion channels defined therein with walls which have any transitions in shape along the length thereof smoothly blended, each of said channels intersecting with adjacent channels at inlet ends which are concentrically disposed about the outer circumference of the compressor rotor in close proximity thereto with a small semi-vaneless diffusion space being defined between the outer circumference and the inlet ends, said diffuser having a primary shock wave formed in the semi-vaneless diffusion space adjacent the inlet ends under normal operating conditions.
Claim 24
Dependent Claim
114 words
A compressor diffuser for use with a supersonic, centrifugal compressor rotor which rotates within an outer circumference about an axis of rotation, the diffuser comprising a diffuser body having a plurality of diffusion channels defined therein with walls which have any transitions in shape along the length thereof smoothly blended, each of said channels intersecting with adjacent channels at inlet ends which are concentrically disposed about the outer circumference of the compressor rotor in close proximity thereto with a small semi-vaneless diffusion space being defined between the outer circumference and the inlet ends, said diffuser having a primary shock wave formed in the semi-vaneless diffusion space adjacent the inlet ends under normal operating conditions.
Claim 25
Dependent Claim
29 words
The compressor diffuser according to claim 20 above, wherein gas flow has a velocity of at least MACH 1.35 on a radially inward side of the primary shock wave.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-14 | 1980-09-13 | 1981-03-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-14 | 1984-09-13 | 1985-03-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-14 | 1988-09-13 | 1989-03-15 | $7700.00 | Window Closed / Lapsed |