Compressor impeller and method of manufacture

Claim 2

A centrifugal compressor impeller, comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis of rotation, a circular cross section transverse to said axis and an arcuate axial section; a plurality of impeller blades on the surface of the conical body adjacent the ase thereof, each impeller blade including a generally radial section extending from an outer end at the base of the body generally toward said axis and an inducer section extending from the truncated end of the body, in a generally axial direction to mmerge smoothly with said generally radial section, each inducer section being defined by parabloic curves wrapped on a series of cylindrical surfaces concentric with the impeller axis, the origin of each parabolic curve being in a plane transverse to the impeller axis and spaced a preselected distance from the truncated end of said body.

Claim 3

The impeller of claim 1 in which at the origins of the parabolas defining an inducer blade, each parabola is tangent to a plane containing the impeller axis and extending radially therefrom.

Claim 4

The impeller of claim 2 in which the form of each parabolic curve is W = KZ.sup.2 (7) where W is the circumferential dimension of the parabola wrapped on one of said cylindrical surfaces; K is the parabolic constant; and Z is the axial dimension of the curve..

Claim 5

The impeller of claim 3 where the constant, K, for each parabola is a function of the diameter of thee cylinder for that parabola.

Claim 6

A centrifugal compressor impeller, comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis of rotation, a circular cross section transverse to said xis and an arcuate axial section; a plurality of impeller blades on the surface of the conical body adjacent the base thereof, each impeller blade including a generally radial section extending from an outer end at the base of the body generally toward said axis and an inducer section extending from the truncated end of the body, in a generally axial direction to merge smoothly with said generally radial section, each inducer section being defined by parabolic curves wrapped on a series of cylindrical surfaces concentric with the impeller axis, the origin of each parabolic curve being in a first plane transverse to the impeller axis and spaced a preselected distance from the truncated end of said body and, at said origins, each parabolic curve being tangent to a second plane which contains the impeller axis and extends radially therefrom, the form of each parabolic curve being defined by the expression W = KZ.sup.2 ( 7) where W is the circumferential dimension of the parabola wrapped on one of said cylindrical surfaces; K is the parabolic constant and, for each parabola, is a function of the diameter of the cylinder for that parabola, and Z is the axial dimension of the curve, the constant K, for each parabola being given by the expression ##EQU8## where K m is the constant for the parabola wrapped on a cylindrical surface of diameter D min

Claim 7

A centrifugal compressor impeller, comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis of rotation, a circular cross section transverse to said xis and an arcuate axial section; a plurality of impeller blades on the surface of the conical body adjacent the base thereof, each impeller blade including a generally radial section extending from an outer end at the base of the body generally toward said axis and an inducer section extending from the truncated end of the body, in a generally axial direction to merge smoothly with said generally radial section, each inducer section being defined by parabolic curves wrapped on a series of cylindrical surfaces concentric with the impeller axis, the origin of each parabolic curve being in a first plane transverse to the impeller axis and spaced a preselected distance from the truncated end of said body and, at said origins, each parabolic curve being tangent to a second plane which contains the impeller axis and extends radially therefrom, the form of each parabolic curve being defined by the expression W = KZ.sup.2 ( 7) where W is the circumferential dimension of the parabola wrapped on one of said cylindrical surfaces; K is the parabolic constant and, for each parabola, is a function of the diameter of the cylinder for that parabola, and Z is the axial dimension of the curve, the constant K, for each parabola being given by the expression ##EQU8## where K m is the constant for the parabola wrapped on a cylindrical surface of diameter D min

Claim 8

K is the constant for the parabola wrapped on a cylindrical surface of diameter D e .

Claim 9

K is the constant for the parabola wrapped on a cylindrical surface of diameter D e .

Claim 10

The impeller of claim 5 in which the surface of each inducer section is substantially flat in a plane radial of the impeller.

Claim 11

A centrifugal compressor impeller blank from which a desired one of a series of impellers is made, said blank comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis, a circular section transverse to the axis and an arcuate section longitudinal of the axis; a plurality of impeller blades on said body, each of said blades including a first section extending inwardly from the base of said body and an inducer section extending from said first section to the truncated end of the body, and said inducer section having an angle with respect to a plane transerse to said axis which is an inverse function of diameter and an inverse function of axial distance from said first section, said inducer section further being defined by curves wrapped on a series of cylindrical surfaces concentric with the impeller axis.

Claim 12

A centrifugal compressor impeller blank from which a desired one of a series of impellers is made, said blank comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis, a circular section transverse to the axis and an arcuate section longitudinal of the axis; a plurality of impeller blades on said body, each of said blades including a first section extending inwardly from the base of said body and an inducer section extending from said first section to the truncated end of the body, and said inducer section having an angle with respect to a plane transerse to said axis which is an inverse function of diameter and an inverse function of axial distance from said first section, said inducer section further being defined by curves wrapped on a series of cylindrical surfaces concentric with the impeller axis.

Claim 13

An impeller cut from the blank of claim 7, having an eye diameter defined as a function of desired flow rate and an axial length selected for an inducer section inlet angle, β, to minimize gas velocity relative to the surface of the inducer section.

Claim 14

The impeller of claim 8 in which the inducer section inlet angle, β, is given by the expression ##EQU9##

Claim 15

The impeller blank of claim 7 in which the inducer sections are defined by parabolic curves of the form W = KZ.sup.2, (7) where W is the circumferential dimension of inducer section around the impeller body, Z is the axial inducer dimension from said first sections of the impeller blades and K is the parabolic constant.

Claim 16

A centrifugal compressor impeller blank from which a desired one of a series of impellers is made, said blank comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis, a circular section transverse to the axis and an arcuate section longitudinal of the axis; a plurality of impeller blades on said body, each of said blades including a first section extending inwardly from the base of said body and an inducer section extending from said first section to the truncated end of the body, and said inducer section having an angle with respect to a plane transverse to said axis which is an inverse function of diameter and an inverse function of axial distance from said first section. said inducer sections being defined by parabolic curves of the form W = Kz.sup.2, (7) W is the circumferential dimension of inducer section around the impeller body, Z is the axial inducer dimension from said first sections of the impeller blades and K is the parabolic constant and is a function of the impeller eye diameter, D e .

Claim 17

A centrifugal compressor impeller blank from which a desired one of a series of impellers is made, said blank comprising; a body formed as a truncated, generally conical body of revolution with a longitudinal axis, a circular section transverse to the axis and an arcuate section longitudinal of the axis; a plurality of impeller blades on said body, each of said blades including a first section extending inwardly from the base of said body and an inducer section extending from said first section to the truncated end of the body, and said inducer section having an angle with respect to a plane transverse to said axis which is an inverse function of diameter and an inverse function of axial distance from said first section. said inducer sections being defined by parabolic curves of the form W = Kz.sup.2, (7) W is the circumferential dimension of inducer section around the impeller body, Z is the axial inducer dimension from said first sections of the impeller blades and K is the parabolic constant and is a function of the impeller eye diameter, D e .

Claim 18

The impeller blank of claim 11 in which the parabolic constant, K, is given by the expression ##EQU10## where Z max is the maximum length of the inducer sections, D min is the minimum eye diameter for the series of impellers, and β m is the inlet angle of the inducer section for maximum inducer length and minimum inducer diameter.

Claim 21

The method of claim 13 for making an impeller in which the impeller eye diameter is established for minimum fluid velocity with respect to the impeller.

Claim 24

The method of claim 13 for making an impeller in which the length of the impeller is cut to establish the inducer section inlet angle, β, for minimum gas velocity relative to the surface of the inducer section.

Claim 25

The method of claim 16 for making an impeller in which the inducer section inlet angle, β, is given by the expression ##EQU12##

Claim 26

A universal impeller blank from which a series of impellers may be formed with different eye diameters, D e , and inlet angles, β, said blank comprising a body formed as a body of revolution about a central axis and having a generaly frustoconical shape with an upper end portion, a base portion and a curved outer surface concave generally toward said central axis, a plurality of impeller blades integrally formed with and protruding from said body, each of said blades including a generally radial section and an inducer section, said radial section extending lengthwise in a generally radial direction and edgewise in a generally axial direction along the base portion of said body, said inducer section extending lengthwise from said radial section in a generally axial direction and edgewise in a generally radial direction along the upper portion of said body, and said inducer section having a working surface generated by a family of at least second order curves having the general formula W = Kf(Z), (6) where W is the circumferential dimension of the curve relative to the axis of the impeller, Z is the axial dimension of the curve, K is a curve constant, and f(Z) represents a function of Z said constant, K, having a value which is a tangent function related to the maximum axial length, Z max of said curves and the minimum eye diameter, D min for the impellers in the series, the value of K also being variable according to the ratio of the radius of said minimum eye diameter to the radial distance of said curve from the axis of said impeller so that the blades of the impeller blank may be trimmed in axial and radial directions to produce a selected impeller of the series.

Claim 27

A universal impeller blank from which a series of impellers may be formed with different eye diameters, D e , and inlet angles, β, said blank comprising a body formed as a body of revolution about a central axis and having a generaly frustoconical shape with an upper end portion, a base portion and a curved outer surface concave generally toward said central axis, a plurality of impeller blades integrally formed with and protruding from said body, each of said blades including a generally radial section and an inducer section, said radial section extending lengthwise in a generally radial direction and edgewise in a generally axial direction along the base portion of said body, said inducer section extending lengthwise from said radial section in a generally axial direction and edgewise in a generally radial direction along the upper portion of said body, and said inducer section having a working surface generated by a family of at least second order curves having the general formula W = Kf(Z), (6) where W is the circumferential dimension of the curve relative to the axis of the impeller, Z is the axial dimension of the curve, K is a curve constant, and f(Z) represents a function of Z said constant, K, having a value which is a tangent function related to the maximum axial length, Z max of said curves and the minimum eye diameter, D min for the impellers in the series, the value of K also being variable according to the ratio of the radius of said minimum eye diameter to the radial distance of said curve from the axis of said impeller so that the blades of the impeller blank may be trimmed in axial and radial directions to produce a selected impeller of the series.

Claim 28

A universal impeller blank as defined in claim 18 where f(Z) = Z.sup.2. 20. 20. A universal impeller blank as defined in claim 19 wherein the value of the curve constant, K, is given by the formula: ##EQU13## where β.sub.m is the theoretical inlet angle for an impeller within the series having the minimum eye diameter, D.sub.min, and maximum curve length Z.sub.max.

Claim 29

A universal impeller blank from which a series of impellers may be formed with different eye diameters, D e , and inlet angles, β, said blank comprising a body formed as a body of revolution about an axis, a plurality of blades integrally formed with said body and protruding therefrom, said blades each having a working surface with at least a portion thereof extending lengthwise in a generally axial direction and edgewise in a generally radial direction relative to said axis, and with said portion being generated by a family of at least second order curves wrapped on cylinders corresponding to the eye diameters, D e , and whose slopes increase upon progressing away from the eye of the impeller, said curves being defined by the general formula W = Kf(Z), (6) where W is the circumferential dimension of the curve relative to the axis of the impeller, Z is the axial dimension of the curve, K is a curve constant, and f(Z) represents a function of Z, said curve constant, K, having a value given by the formula, ##EQU14## where D min is the minimum eye diameter for the impellers in the series, and f'(Z) max is the value of the first derivative of (6) for the maximum axial dimension, Z max , of the curves for the impellers in the series, and β m is the theoretical inlet angle for an impeller within the series having the minimum eye diameter, D min , and maximum axial curve length, Z max .

Claim 30

A universal impeller blank from which a series of impellers may be formed with different eye diameters, D e , and inlet angles, β, said blank comprising a body formed as a body of revolution about an axis, a plurality of blades integrally formed with said body and protruding therefrom, said blades each having a working surface with at least a portion thereof extending lengthwise in a generally axial direction and edgewise in a generally radial direction relative to said axis, and with said portion being generated by a family of at least second order curves wrapped on cylinders corresponding to the eye diameters, D e , and whose slopes increase upon progressing away from the eye of the impeller, said curves being defined by the general formula W = Kf(Z), (6) where W is the circumferential dimension of the curve relative to the axis of the impeller, Z is the axial dimension of the curve, K is a curve constant, and f(Z) represents a function of Z, said curve constant, K, having a value given by the formula, ##EQU14## where D min is the minimum eye diameter for the impellers in the series, and f'(Z) max is the value of the first derivative of (6) for the maximum axial dimension, Z max , of the curves for the impellers in the series, and β m is the theoretical inlet angle for an impeller within the series having the minimum eye diameter, D min , and maximum axial curve length, Z max .

Claim 31

A centrifugal compressor impeller, comprising; a body formed as a truncated, generaly conical body of revolution with a longitudinal axis of rotation, a circular cross section transverse to said axis and an arcuate axial section; a plurality of impeller blades on the surface of the conical body adjacent the base thereof, each impeller blade including a generally radial section extending from an outer end at the base of the body generally toward said axis and an inducer section extending from the truncated end of the body, in a generally axial direction to merge smoothly with said generally radial section, each inducer section being defined by curves wrapped on a series of cylindrical surfaces concentric with the impeller axis, the origin of each curve being in a first plane transverse to the impeller axis and spaced a preselected distance from the truncated end of said body and, at said origins, each curve being generally tangent to a second plane which contains the impeller axis and extends radially therefrom, the form of each curve being defined by the expression W = Kf (Z) (7) where W is the circumferential dimension of the curve wrapped on one of said cylindrical surfaces; Z is the axial dimension of the curve, f(Z) represents the curve function of Z, and K is the curve constant and, for each curve is a function of the diameter of the cylinder for that curve, and for each curve is given by the expression ##EQU15## where K m is the constant for the curve wrapped on a cylindrical surface of diameter D min K is the constant for the curve wrapped on a cylindrical surface of diameter D e .

Claim 32

A centrifugal compressor impeller, comprising; a body formed as a truncated, generaly conical body of revolution with a longitudinal axis of rotation, a circular cross section transverse to said axis and an arcuate axial section; a plurality of impeller blades on the surface of the conical body adjacent the base thereof, each impeller blade including a generally radial section extending from an outer end at the base of the body generally toward said axis and an inducer section extending from the truncated end of the body, in a generally axial direction to merge smoothly with said generally radial section, each inducer section being defined by curves wrapped on a series of cylindrical surfaces concentric with the impeller axis, the origin of each curve being in a first plane transverse to the impeller axis and spaced a preselected distance from the truncated end of said body and, at said origins, each curve being generally tangent to a second plane which contains the impeller axis and extends radially therefrom, the form of each curve being defined by the expression W = Kf (Z) (7) where W is the circumferential dimension of the curve wrapped on one of said cylindrical surfaces; Z is the axial dimension of the curve, f(Z) represents the curve function of Z, and K is the curve constant and, for each curve is a function of the diameter of the cylinder for that curve, and for each curve is given by the expression ##EQU15## where K m is the constant for the curve wrapped on a cylindrical surface of diameter D min K is the constant for the curve wrapped on a cylindrical surface of diameter D e .