GB2068461A

GB2068461A - Regenerative turbo machines

Info

Publication number: GB2068461A
Application number: GB8003473A
Authority: GB
Original assignee: UTILE ENG CO Ltd
Current assignee: UTILE ENG CO Ltd
Priority date: 1980-02-01
Filing date: 1980-02-01
Publication date: 1981-08-12

Abstract

The machine is provided with one or more breather passages 17 in a stripper 16 which separates the inlet port 14 and outlet port 15 of the toroidal channel 13 in which the vanes or blades 12 of its rotor 11 rotate. Fluid trapped between the vanes and carried into the stripper is bled therefrom and the passage or passages are shaped and disposed to direct such fluid to escape in a path or paths which will induce or enhance flow through the inlet port. Fluid from the stripper may be injected into the inlet port along its walls in the direction of inflow to provide a venturi effect and reduce turbulence, and/or it may be led into the inlet end of the toroidal channel 13 in a region of the channel on the side of the rotor remote from the inlet port. <IMAGE>

Description

SPECIFICATION Regenerative turbo machines This invention relates to re,generative fluid dynamic turbo machines for compressing, pumping, boosting or exhausting air or other gases.

Regenerative (also referred to as "side channel" or "vortex flow") machines incorporate a rotor revolving within a stator or casing defining an annular channel which accommodates a peripheral part of the rotor, this part being provided with a plurality of vanes (which may be blades, hollows or bucket formations). The channel walls are spaced from the vanes to form an open toroidal passage extending angularly around a major portion (e.g. about 3400) of said periphery between inlet and outlet ports in the casing, the remaining minor portion being reduced in cross-section by a stripper formation of the casing to minimum clearance over the vanes so as to permit their rotation but, so far as practicable, to prevent or restrict passage of fluid through that minor portion between the inlet and outlet ports.

In operation fluid follows a path between the inlet and outlet ports which has compound curvature not only passing around the rotor axis but also spiralling in a vortex or vortices about a centre or centres within the cross section of the channel to enter and leave the rotor vanes at intervals as the rotor rotates. Thus there is interaction between the vanes and the same particles or portions of the fluid several times between the inlet and outlet so that the equivalent of multistage compression is achieved using a single set of rotor blades or vanes, the fluid being acted upon by the same set of blades or vanes more than once during its passage through the channel.

Sadi machines are hereinafter referred to as "regenerative machines of the kind described".

Some examples of this kind of machine are described in greater detail in our co-pending British Patent Application No. 7943255 dated 14th December 1 979 to which reference is made.

The object of the present invention is to provide greater efficiency in said kind of machine.

According to the invention there is provided a regenerative machine of the kind described wherein the stripper formation is formed to provide one or more passages opening from an intermediate region or regions of said formation into the area of the inlet port whereby compressed fluid carried into the stripper formation with the blades is directed for escape in a path or paths which will induce or enhance the inflow of fluid through said port.

Said passage or passages may take the form of ducts opening at an angle into the inlet port to inject fluid thereinto in the direction of inflow and/ar said passage or passages may be defined by shaped walls of the blade passage through the stripper formation guiding the fluid in a direction and at a velocity which will induce or enhance flow from the inlet port and reduce turbulence in the immediately adjacent end part of the toroidal channel.

Said fluid may be injected or guided for flow along the walls of the inlet port and/or said adjacent end of the channel in the direction of flow therethrough with the effect of enhancing said flow by reducing turbulence in the inlet region and/or providing inducement of flow by a venturi effect.

Specific embodiments of the invention are now described in detail with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic section of a regenerative machine on a median plane normal to the rotor axis.

Figure 2 is a section on line 2-2 of Figure 1; Figure 3 is a like section to Figure 2 showing another form of the invention; and Figures 4 and 5 are respectively a side elevation and radial sectional view of an inlet port construction.

Figure 1 shows the basic arrangements of the machine including its stator or casing 10, rotor 11 having peripheral vanes 12 travelling in toroidal channel 13 of the stator which extends between an inlet port 14 and an outlet port 15, the inlet and outlet ends of channel 1 3 being separated by a stripper formation 1 6 fitting with minimum practicable running clearance around the vanes 1 2 to prevent direct passage of fluid from the inlet to the outlet and to reduce, so far as possible, carry over of fluid in the vanes.

Referring now to the detailed diagrammatic view of Figure 2, bleed passages 1 7 are provided within stripper formation 1 6 leading from intermediate regions thereof to open through the walls of inlet port 14 adjacent to its junction with the inlet end of channel 1 3. The passage openings into said port are angled in the direction of inflow therethrough so as to induce or enhance the latter flow and to reduce turbulence.

During operation the pockets of compressed fluid carried into stripper formation 1 6 between the adjacent pairs of blades or vanes 12 are able to expand into the bleed passages 1 7 and said compressed fluid is applied to increase the efficiency of the inlet "breathing" of the machine (rather than being released indiscriminately as the blades leave the stripper formation in a way which with known patterns of machine, is believed to substantially reduce efficiency at the vital inlet end of the channel 1 3) so that smooth and positive setting up of the vortex flow or flows within the channel is aided rather than hindered.Moreover early release of pressure from the pockets defined between blades 1 2 means that they are at or near inlet pressure as soon as they leave the stripper formation and are thus ready to receive the inflow from the inlet port 14.

Figure 3 shows an alternative arrangement (which could possibly be combined with the arrangement shown in Figure 2) in which a part of the mouth of the blade passage in stripper formation 1 6a is cut away at an angle at 1 8 to form a passage directing flow of compressed fluid trapped in the blade pockets into channel 13 on the side remote from the entry of inlet port 14 and in a direction which will enhance or induce the spiral or vortex flow in channel 13 aided, in this case, by the aerofoil curvature of blades or vanes 12 in the manner described in our said co-pending Patent Application No. 7943255. This arrangement substantially reduces or avoids loss of efficiency due to turbulence otherwise caused by the fluid suddenly expanding indiscriminately out of the vane pockets at the inlet end of channel 13.

The inlet flow characteristics of either of the above described arrangements may be further enhanced by the provision of a guide plate or similar formation to direct the flow through inlet port 14 onto the inlet port side of blades or vanes 12. A construction for this purpose is shown in Figures 4 and 5 where a circular section inlet duct terminates in a port 1 4a defined in part by a baffle or deflector plate 20 extending the upper (as viewed in the drawings) wall of port 1 4a to minimum clearance proximity to an annular shroud 21 mounted on the radially outer tips of blades 12. This directs inflow through port 1 4a directly into the pockets defined between the blades and keeps it substantially separated from air already present at the inlet end of toroidal channel- 13 whether carried through the stripper formation (not shown in Figures 4 and 5) or otherwise.

Claims

1. A regenerative machine of the kind described wherein the stripper formation is formed to provide one or more passages opening from an intermediate region or regions of said formation into the area of the inlet port whereby compressed fluid carried into the stripper formation with the blades is directed for escape in a path or paths which will induce or enhance the inflow of fluid through said port.

2. A machine as in Claim 1 wherein said one or more passages include one or more ducts opening at one end into said intermediate region or regions and at their other end into the inlet port at an angle for injection of fluid thereinto in the direction of operative inflow therethrough.

3. A machine as in Claim 2 wherein said one or more ducts open into the inlet port adjacent to its junction with the inlet end of the annular channel.

4. A machine as inClaim 2 or 3 wherein said fluid is injected for flow along the walls of the inlet port for reduction of turbulence in the inlet region and/or inducing or enhancing the inflow by a verturi effect.

5. A machine as in any one of the preceding claims wherein said one or more passages include a passage or passages defined by shaping those wall of the stripper formation providing said minimum clearance over the vanes in an area adjoining the mouth through which the blades exit from the stripper formation.

6. A machine as in Claim 5 wherein said shaping comprises the cutting away at an angle of part of said mouth to direct flow of compressed fluid trapped in the vane pockets within the stripper into the inlet end of the annular channel on a side remote from the junction with the inlet port.

7. A machine as in Claim 6 including a guide formation at said junction to direct inflow from the inlet port between the vanes while separating it from fluid already present in other regions of the inlet end of the annular channel.

8. A machine as in any one preceding claim wherein the vanes are shaped with aerofoil curvature.

9. A machine as in any one of the preceding claims including an annular shroud mounted on tips of the vanes.

10. A regenerative fluid dynamic turbo machine substantially as hereinbefore described with reference to and as shown in Figures 1 and 2, Figure 3, or Figures 4 and 5 of the accompanying drawings.