Diffuser for a centrifugal compressor

Claim 2

A diffuser for a centrifugal compressor having an impeller comprising: an annular housing: a plurality of passages spaced about the circumference of said housing and extending therethrough, adjacent ones of said passages intersecting with each other at radially inner inlet portions thereof for defining a quasi-vaneless annular inlet of said diffuser, each of said passages further including a throat portion integral with said inlet portion, said throat portion having a first quadrilateral cross section including two substantially parallel linear opposing sidewalls and two substantially arcuate opposing sidewalls, said two linear sidewalls being spaced from each other to define a minor dimension extending therebetween, said two arcuate sidewalls being spaced from each other to define a major dimension therebetween, said major dimension being greater in length than said minor dimension, and said linear sidewalls being disposed substantially normal with respect to a radial axis of said diffuser.

Claim 3

A diffuser according to claim 1 wherein said first quadrilateral cross section has an area and said linear opposing sidewalls are spaced from each other a distance less than the diameter of a circle having an area equal to said quadrilateral area.

Claim 4

A diffuser according to claim 1 wherein said linear sidewalls are spaced from each other a distance 2b, each of said arcuate sidewalls of said throat portion is defined by a radius R extending from a center point of said throat portion, said throat portion has a cross sectional area A, and R, A and b are related to each other as follows: ##EQU4##

Claim 5

A diffuser according to claim 3 wherein said distance b represents one half the tip width of blades of said impeller.

Claim 6

A diffuser according to claim 1 wherein said throat portion extends with a constant area in a tangential direction for a length generally equal to the diameter of a circle having an area equal to the area of said first quadrilateral cross section of said throat portion.

Claim 7

A diffuser according to claim 1 wherein said plurality of passages further includes a diffuser portion integral with said throat portion and having at a downstream end a second quadrilateral cross section including two substantially parallel opposing linear sidewalls and two substantially acruate opposing sidewalls.

Claim 8

A diffuser according to claim 6 wherein said diffuser portion further includes at an upstream end a third quadrilateral cross section substantially identical to said first quadrilateral cross section of said throat portion, said diffuser portion being gradually tapered between said upstream and downstream ends.

Claim 9

A diffuser according to claim 6 wherein said second quadrilateral cross section is oriented substantially 90 degrees with respect to said first quadrilateral cross section.

Claim 10

A diffuser according to claim 1 wherein each of said inlet portions defines a partially bounded passage having a generally semi-circular cross section at an upstream end thereof which is open at opposing base and apex portions thereof, said nlet portion tapering from said semi-circular cross section to said first quadrilateral cross section of said throat portion.

Claim 11

A diffuser according to claim 9 wherein said adjacent ones of said inlet portions intersect with each other to define step portions extending and tapering from said throat portion to said upstream end of said inlet portion.

Claim 12

A diffuser according to claim 10 wherein said step portions include flat, radially outwardly facing surfaces defined by portions of said linear opposing sidewalls and arcuate, radially inwardly facing surfaces defined by portions of said arcuate opposing sidewalls.

Claim 13

In a diffuser of a centrifugal compressor including an impeller, said diffuser including a plurality of tangentially disposed passages each having a throat portion of cross-sectional area A, the improvement comprising: said throat portion having a quadrilateral cross section defined by two substantially parallel opposing linear sidewalls and two substantially arcuate opposing sidewalls, said two linear sidewalls being spaced from each other to define a minor dimension extending therebetween, said two arcuate sidewalls being sapced from each other to define a major dimension therebetween, said major dimension being greater in length than said minor dimension, and said linear sidewalls being disposed substantially normal with respect to a radial axis of said diffuser.

Claim 14

In a diffuser of a centrifugal compressor including an impeller, said diffuser including a plurality of tangentially disposed passages each having a throat portion of cross-sectional area A, the improvement comprising: said throat portion having a quadrilateral cross section defined by two substantially parallel opposing linear sidewalls and two substantially arcuate opposing sidewalls, said two linear sidewalls being spaced from each other to define a minor dimension extending therebetween, said two arcuate sidewalls being sapced from each other to define a major dimension therebetween, said major dimension being greater in length than said minor dimension, and said linear sidewalls being disposed substantially normal with respect to a radial axis of said diffuser.

Claim 15

An improved diffuser according to claim 12 wherein said linear sidewalls are spaced from each other a distance 2b, each of said arcuate sidewalls is defined by a radius R extending from a center point of said throat portion, and wherein R, A and b are related to each other as follows: ##EQU5##

Claim 16

An improved diffuser according to claim 13 wherein said distance b represents one half the tip width of blades of said impeller.

Claim 17

An improved diffuser according to claim 12 wherein said quadrilateral cross sections has an area and said linear opposing sidewalls are spaced from each other a distance less than the diameter of a circle having an area equal to said quadrilateral area.

Claim 18

A diffuser according to claim 12 wherein each of said inlet portions defines a partially bounded passage having a generally semi-circular cross section at an upstream end thereof which is open at opposing base and apex portions thereof, said inlet portion tapering from said semi-circular cross section to said first quadrilateral cross section of said throat portion.

Claim 19

A diffuser according to claim 16 wherein said adjacent ones of said inlet portions intersect with each other to define step portions extending and tapering from said throat portion to said upstream end of said inlet portion.

Claim 20

A diffuser according to claim 17 wherein said step Portions include flat, radially outwardly facing surfaces defined by portions of said linear opposing sidewallls and arcuate, radially inwardly facing surfaces defined by portions of said arcuate opposing sidewalls.

Claim 21

A diffuser for a centrifugal compressor having an impeller comprising: an annular housing; a plurality of passages spaced about the circumference of said housing and extending therethrough, adjacent ones of said passages intersecting with each other at radially inner inlet portions thereof for defining a quasi-vaneless annular inlet of said difuser, each of said passages further including a throat portion integral with said inlet portion, said throat portion having a first quadrilateral cross section including two substantially parallel linear opposing sidewalls and two substantially arcuate opposing sidewalls, said two linear sidewalls being spaced from each other to define a minor dimension extending therebetween, said two arcuate sidewalls being spaced from each other to define a major dimension therebetween, said major dimension being greater in length than said minor dimension, and said linear sidewalls being disposed substantially normal with respect to a radial axis of said diffuser; said first quandrilateral cross section having an area and said linear opposing sidewalls being spaced from each other with said minor dimension being less than the diameter of a circle having an area equal to said first quadrilateral area; each of said inlet portions defining a partially bounded passage having a generally semi-circular cross section at an upstream end thereof which is open at opposing base and apex portions thereof, said inlet portion tapering from said semi-circular cross section to said first quadrilateral cross section of said throat portion; said adjacent ones of said inlet portions intersecting each other to define step portions extending and tapering from said throat portion to said upstream end of said inlet portion; said step portions including flat, radially outwardly facing surfaces defined by portions of said linear opposing sidewalls and arcuate, radially inwardly facing surfaces defined by portions of said arcuate opposing sidewalls; said throat portion extending with a constant area in a tangential direction for a length generally equal to the diameter of a circle having an area to the area of said first quadrilateral cross section of said throat portion; said plurality of passages further including a diffuser portion integral with said throat portion and having at a downstream end a second quadrilateral cross section including two substantially parallel opposing linear sidewalls and two substantially arcuate opposing sidewalls; said diffuser portion further including at an upstream end a third quadrilateral cross section substantially identical to said first quadrilateral cross section of said throat portion, said diffuser portion being gradually tapered between said upstream and downstream ends; and said second quadrilateral cross section being oriented substantially 90 degrees with respect to said first quadrilateral cross section.

Claim 22

A diffuser for a centrifugal compressor having an impeller comprising: an annular housing; a plurality of passages spaced about the circumference of said housing and extending therethrough, adjacent ones of said passages intersecting with each other at radially inner inlet portions thereof for defining a quasi-vaneless annular inlet of said difuser, each of said passages further including a throat portion integral with said inlet portion, said throat portion having a first quadrilateral cross section including two substantially parallel linear opposing sidewalls and two substantially arcuate opposing sidewalls, said two linear sidewalls being spaced from each other to define a minor dimension extending therebetween, said two arcuate sidewalls being spaced from each other to define a major dimension therebetween, said major dimension being greater in length than said minor dimension, and said linear sidewalls being disposed substantially normal with respect to a radial axis of said diffuser; said first quandrilateral cross section having an area and said linear opposing sidewalls being spaced from each other with said minor dimension being less than the diameter of a circle having an area equal to said first quadrilateral area; each of said inlet portions defining a partially bounded passage having a generally semi-circular cross section at an upstream end thereof which is open at opposing base and apex portions thereof, said inlet portion tapering from said semi-circular cross section to said first quadrilateral cross section of said throat portion; said adjacent ones of said inlet portions intersecting each other to define step portions extending and tapering from said throat portion to said upstream end of said inlet portion; said step portions including flat, radially outwardly facing surfaces defined by portions of said linear opposing sidewalls and arcuate, radially inwardly facing surfaces defined by portions of said arcuate opposing sidewalls; said throat portion extending with a constant area in a tangential direction for a length generally equal to the diameter of a circle having an area to the area of said first quadrilateral cross section of said throat portion; said plurality of passages further including a diffuser portion integral with said throat portion and having at a downstream end a second quadrilateral cross section including two substantially parallel opposing linear sidewalls and two substantially arcuate opposing sidewalls; said diffuser portion further including at an upstream end a third quadrilateral cross section substantially identical to said first quadrilateral cross section of said throat portion, said diffuser portion being gradually tapered between said upstream and downstream ends; and said second quadrilateral cross section being oriented substantially 90 degrees with respect to said first quadrilateral cross section.

Claim 23

A diffuser according to claim 19 wherein: said impeller includes blades each having a tip width of 2b; said first quadrilateral cross section of said throat portion has an area A; said linear sidewalls of said first quadrilateral cross section are sapced from each other such that said minor dimension equals 2b; said arcuate sidewalls of said first quadrilateral cross section are each defined by a radius R and said major dimension equals 2R; and said area A, said radius R, and said dimension b are related to each other as follows: ##EQU6##