Active surge control in centrifugal compressors using microjet injection
A centrifugal compressor according to an exemplary aspect of the present disclosure includes, among other things, an impeller provided in a main flow path and configured to pressurize a main flow of fluid. The compressor also includes a secondary flow path configured to provide a secondary flow by recirculating a portion of the main flow. The amount of the main flow that becomes the secondary flow is less than or equal to 15%. A method is also disclosed.
1. A centrifugal compressor, comprising:
an impeller provided in a main flow path and configured to pressurize a main flow of fluid; and
a secondary flow path configured to provide a secondary flow by recirculating a portion of the main flow, wherein less than or equal to 15% of the main flow becomes the secondary flow, wherein the secondary flow is introduced back into the main flow path by a plurality of injection nozzles each having a diameter within a range of 300 to 500 microns, and wherein the injection nozzles are circumferentially spaced-apart from one another by an arc length within a range of 8 to 25 of the diameters.
2. The compressor as recited in claim 1 , wherein less than or equal to 10% of the main flow becomes the secondary flow.
3. The compressor as recited in claim 2 , wherein 8.5% of the main flow becomes the secondary flow.
4. The compressor as recited in claim 1 , including an injection plate, the injection nozzles formed in the injection plate.
5. The compressor as recited in claim 1 , wherein the secondary flow path includes one of a volute and a plenum adjacent inlets of the injection nozzles.
6. The compressor as recited in claim 1 , wherein the plurality of injection nozzles are configured to introduce the secondary flow into the main flow path in a direction normal to a direction of the flow of fluid in the main flow path.
7. The compressor as recited in claim 1 , wherein the plurality of injection nozzles are radially aligned with one another relative to an axis of rotation of the impeller.
8. The compressor as recited in claim 7 , wherein the plurality of injection nozzles are evenly spaced-apart from one another in a circumferential direction.
9. The compressor as recited in claim 8 , wherein the plurality of injection nozzles have the same diameter.
10. The compressor as recited in claim 1 , wherein the secondary flow is reintroduced back into the main flow path at a location downstream of the impeller.
11. The compressor as recited in claim 10 , wherein the impeller is a first impeller within the main flow path, and wherein the compressor further includes a second impeller within the main flow path, the second impeller downstream of the first impeller.
12. The compressor as recited in claim 11 , wherein the secondary flow enters the secondary flow path at a location downstream of the second impeller.
13. The compressor as recited in claim 1 , further including:
a controller; and
a flow regulator provided in the secondary flow path, the flow regulator selectively regulating the secondary flow within the secondary flow path in response to instructions from the controller.
14. A centrifugal compressor, comprising:
an impeller provided in a main flow path and configured to pressurize a main flow of fluid;
a secondary flow path configured to provide a secondary flow into the main flow; and
injection nozzles configured to introduce the secondary flow back into the main flow path, the injection nozzles each having a diameter within a range of 300 to 500 microns, wherein the injection nozzles are radially aligned relative to an axis of rotation of the impeller and are also circumferentially spaced-apart from one another by an arc length within a range of 8 and 25 of the diameters.
15. The compressor as recited in claim 14 , wherein less than or equal to 15% of the main flow is recirculated and becomes the secondary flow.
16. A method of operating a centrifugal compressor, comprising:
establishing a main flow of fluid along a main flow path;
pressurizing the main flow with an impeller; and
selectively providing a secondary flow by recirculating less than or equal to 15% of the main flow, wherein the secondary flow is introduced back into the main flow path by a plurality of injection nozzles, the injection nozzles each having a diameter within a range of 300 to 500 microns, wherein the plurality of injection nozzles are circumferentially spaced-apart from one another by an arc length within a range of 5 and 8 millimeters.