GB2057567A - Expanding scroll diffuser for radial flow impeller - Google Patents

Abstract

In a discharge scroll 10 for a fluid flow device such as a compressor having an impeller, the cross-sectional area C1-C2 of the scroll progressively increasing from entry to discharge, the outer diameter D is substantially uniform. The inner diameter may also be substantially uniform. <IMAGE>

Description

SPECIFICATION Expanding scroll diffuser for radial flow impeller Compressed gases exiting from a radial impeller diffuse in all directions at a relatively high gas velocity. To improve the efficiency of such a system, it is necessary to reduce the velocity of flow to a practical minimum. Friction flow losses, as a result, are reduced and better efficiencies are realized for the system.

Conventional diffusers associated with fluid devices, such as impeller compressors, are typically of the radial expansion type with a substantially constant axial dimension which feeds into a long, cone-shaped funnel-like expansion chamber. Such construction permits gradual reduction of the velocity of the fluid such as gases and the like.

It is desirable that the diffuser be part of the compressor housing or housing package to keep the unit size as small as possible without affecting the efficiency of the device.

According to the invention, a fluid flow device, such as an impeller compressor, is provided with a discharge scroll having a substantially uniform outer diameter and a progressively increasing cross-sectional area from inlet to discharge. In one embodiment the inner diameter of the discharge scroll is also uniform. Generally the progressively increasing scroll cross-sectional area is accommodated by progressively increasing the axial dimensions of the scroll.

The configuration provides a relatively small, compact unit without affecting the efficiency of the device.

One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment, in which: - FIG. 1 is a plan view of a one embodiment of a discharge scroll according to this invention: FIG. 2 is a sectional view through the scroll of FIG. 1 with an associated impeller in broken lines; FIG. 3 is a plan view of another embodiment of a discharge scroll of this invention; and FIG. 4 is a sectional view of the discharge scroll of FIG. 3.

Looking now at the drawings, and especially FIGS. 1 and 2, where a first embodiment is illustrated, there is shown a discharge scroll 10 associated with an impeller 12 (FIG. 2) such that fluid is discharged with an impeller 12 (FIG. 2) such that fluid is discharged from the impeller, as indicated by appropriate arrows, into the scroll at the inside and expands and flows to the discharge 14. When looking at FIG. 1, it is observed that the outer diameter, identified as D is constant while the inner diameter varies and becomes smaller from inlet to discharge; FIG. 2 indicates that the axial length progressively increases from intake to discharge. FIG. 2 also shows the cross section of the scroll (C1, C2) at two locations, such progressively increasing from intake to discharge.

Turning now to FIGS. 3 and 4, there is shown a second embodiment in which the discharge scroll 20 is associated with an impeller 22 (FIG. 4). The fluid is discharged from the impeller into the scroll as indicated by appropriate arrows and expands and flows to the discharge 24. It is to be observed that the outer diameter OD as well as the inner diameter ID are constant, the axial length progressively increasing from intake to discharge.

FIG. 4, as FIG. 2, shows the cross-section of the scroll (C3, C4) at two locations, such progressively increasing from intake to discharge.

1. In a fluid flow device having an impeller and an associated discharge scroll in which the crosssectional area increases from entry to discharge, the improvement comprising: a substantially uniform outer diameter scroll with a progressively increasing cross-sectional area from entry to discharge.

2. In a fluid flow device as recited in Claim 1 wherein said scroll progressively increases in axial length.

3. In a fluid flow device as recited in Claim 1 wherein said scroll has a substantially uniform inner diameter.

4. In a fluid flow device as recited in Claim 1 wherein said scroll has a substantially uniform inner diameter and progressively increases in axial length.

5. A fluid flow device substantially as herein described with reference to Figures 1 and 2, or Figures 3 and 4, of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Expanding scroll diffuser for radial flow impeller Compressed gases exiting from a radial impeller diffuse in all directions at a relatively high gas velocity. To improve the efficiency of such a system, it is necessary to reduce the velocity of flow to a practical minimum. Friction flow losses, as a result, are reduced and better efficiencies are realized for the system. Conventional diffusers associated with fluid devices, such as impeller compressors, are typically of the radial expansion type with a substantially constant axial dimension which feeds into a long, cone-shaped funnel-like expansion chamber. Such construction permits gradual reduction of the velocity of the fluid such as gases and the like. It is desirable that the diffuser be part of the compressor housing or housing package to keep the unit size as small as possible without affecting the efficiency of the device. According to the invention, a fluid flow device, such as an impeller compressor, is provided with a discharge scroll having a substantially uniform outer diameter and a progressively increasing cross-sectional area from inlet to discharge. In one embodiment the inner diameter of the discharge scroll is also uniform. Generally the progressively increasing scroll cross-sectional area is accommodated by progressively increasing the axial dimensions of the scroll. The configuration provides a relatively small, compact unit without affecting the efficiency of the device. One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment, in which: - FIG. 1 is a plan view of a one embodiment of a discharge scroll according to this invention: FIG. 2 is a sectional view through the scroll of FIG. 1 with an associated impeller in broken lines; FIG. 3 is a plan view of another embodiment of a discharge scroll of this invention; and FIG. 4 is a sectional view of the discharge scroll of FIG. 3. Looking now at the drawings, and especially FIGS. 1 and 2, where a first embodiment is illustrated, there is shown a discharge scroll 10 associated with an impeller 12 (FIG. 2) such that fluid is discharged with an impeller 12 (FIG. 2) such that fluid is discharged from the impeller, as indicated by appropriate arrows, into the scroll at the inside and expands and flows to the discharge 14. When looking at FIG. 1, it is observed that the outer diameter, identified as D is constant while the inner diameter varies and becomes smaller from inlet to discharge; FIG. 2 indicates that the axial length progressively increases from intake to discharge. FIG. 2 also shows the cross section of the scroll (C1, C2) at two locations, such progressively increasing from intake to discharge. Turning now to FIGS. 3 and 4, there is shown a second embodiment in which the discharge scroll 20 is associated with an impeller 22 (FIG. 4). The fluid is discharged from the impeller into the scroll as indicated by appropriate arrows and expands and flows to the discharge 24. It is to be observed that the outer diameter OD as well as the inner diameter ID are constant, the axial length progressively increasing from intake to discharge. FIG. 4, as FIG. 2, shows the cross-section of the scroll (C3, C4) at two locations, such progressively increasing from intake to discharge. CLAIMS

1. In a fluid flow device having an impeller and an associated discharge scroll in which the crosssectional area increases from entry to discharge, the improvement comprising: a substantially uniform outer diameter scroll with a progressively increasing cross-sectional area from entry to discharge.

2. In a fluid flow device as recited in Claim 1 wherein said scroll progressively increases in axial length.

3. In a fluid flow device as recited in Claim 1 wherein said scroll has a substantially uniform inner diameter.

4. In a fluid flow device as recited in Claim 1 wherein said scroll has a substantially uniform inner diameter and progressively increases in axial length.

5. A fluid flow device substantially as herein described with reference to Figures 1 and 2, or Figures 3 and 4, of the accompanying drawings.