COMPRESSOR INCLUDING AERODYNAMIC TURBULENCE BETWEEN INLET GUIDE VANES AND IMPELLER BLADES

Description

[0001] The present invention relates to a compressor. Compressors are used for a variety of purposes when pressurized fluid or gas is needed. For example, refrigerant circuits utilize pressurized refrigerant to achieve cooling for refrigeration or air conditioning. A variety of compressor configurations have been used in refrigerant circuits.

[0002] One challenge associated with some compressors is achieving optimum efficiency during a variety of operating conditions. For example, the compressor may not need to operate at full capacity under so-called part-load conditions. It would be useful to avoid aerodynamic losses in the impeller under such conditions because such losses negatively affect the compressor efficiency and surge margin. US 2019 / 107111 A1 discloses a centrifugal compressor having a recirculation structure configured to impart a swirl to a flow of refrigerant into the compressor inlet portion. US 2013 / 000315 A1 discloses a compressor having nozzles positioned to inject compressed air into its inlet region to create a swirl in the inlet air flow.

[0003] According to a first aspect there is provided a compressor including an inlet defining an intake passage, a plurality of inlet guide vanes, an impeller, and a plurality of swirl nozzles. Fluid flow through the plurality of inlet guide vanes into the intake passage is selectively adjustable to control fluid flow through at least a portion of the intake passage downstream of the swirl nozzles. The impeller includes a plurality of blades and directs fluid from the intake passage toward an outlet. The swirl nozzles have outlets positioned downstream of the plurality of inlet guide vanes and upstream of the impeller. The swirl nozzles are configured to introduce fluid into the intake passage to cause swirl of fluid in the intake passage between the plurality of inlet guide vanes and the impeller. The plurality of blades have leading edges extending between a hub at a center of the impeller and a shroud at an outer boundary of the impeller, each swirl nozzle of the plurality of swirl nozzles has: a fluid inlet that receives pressurized fluid from the outlet; and a fluid outlet configured to introduce fluid into the intake passage, the fluid outlet having a selectively adjustable outlet direction, and the swirl of fluid introduced by the plurality of swirl nozzles controls an incidence angle of fluid encountering the leading edges of the plurality of blades.

[0004] Optionally, the compressor includes at least one control valve that controls an amount of the received fluid that is introduced into the intake passage.

[0005] Optionally, the at least one control valve controls the amount of the fluid from the outlet provided to more than one of the plurality of swirl nozzles.

[0006] Optionally, the at least one control valve comprises a plurality of control valves and each of the plurality of swirl nozzles is associated with one of the plurality of control valves.

[0007] Optionally, the outlet direction of fluid introduction into the intake passage from the fluid outlets is varied by changing an orientation or position of the fluid outlets relative to the intake passage.

[0008] Optionally, the plurality of swirl nozzles are equidistantly spaced around a circumference of the intake passage

[0009] Optionally, a controller controls at least one of an amount of fluid flowing through the plurality of swirl nozzles and a direction of fluid flow from the plurality of swirl nozzles.

[0010] Optionally, the controller controls to control a flow rate of fluid upstream of the impeller.

[0011] Optionally, the controller controls the incidence angle of fluid flow onto the blades of the impeller.

[0012] Optionally, the controller determines when the compressor operates in a part-load condition and controls the at least one of the amount of fluid flow through the plurality of swirl nozzles and the direction of fluid flow from the plurality of swirl nozzles based on the part-load condition.

[0013] Optionally, the controller increases the amount of fluid flow through at least one of the plurality of swirl nozzles when the compressor operates in the part-load condition.

[0014] Optionally, the controller increases the amount of fluid flow through all of the plurality of swirl nozzles when the compressor operates in the part-load condition.

[0015] Optionally, a controller controls the incidence angle of fluid flow onto the blades, the swirl of fluid in the intake passage caused by the plurality of swirl nozzles establishes the incidence angle of fluid encountering the impeller blades along at least a portion of the leading edge of the blades that achieves a selected compressor efficiency, and the controller optimizes the incidence angle for each location along a length of the leading edge of the blades.

[0016] Optionally, the leading edges of the blades have a length between the hub and the shroud, and the established incidence angle varies along the length of the leading edges of the blades.

[0017] Optionally, the fluid outlet of each swirl nozzle is moveable into a plurality of oblique angles relative to a primary flow direction within the intake passage of the inlet.

[0018] The various features and advantages of at least one disclosed example embodiment will become apparent to those skilled in the art from the following detailed description. The at least one disclosed example embodiment will now be described by way of example only and with reference to the accompanying drawings. The drawings that accompany the detailed description can be briefly described as follows: Figure 1 schematically illustrates a compressor including aerodynamic pre-swirl; and Figure 2 schematically illustrates a nozzle and valve configuration.

[0019] Figure 1 schematically illustrates selected features of an example embodiment of a compressor 20. An inlet 22 defines an intake passage. The inlet 22 includes a plurality of inlet guide vanes 24 that are selectively controlled to adjust an amount of fluid flow through the intake passage. For example, the inlet guide vanes 24 are rotatable about respective radial axes to at least partially reduce the open area within the intake passage when reduced flow is desired.

[0020] An impeller 26 includes a plurality of blades 28 that have leading edges extending between a hub 30 at a center of the impeller 26 and a shroud 32 at an outer boundary of the impeller 26. As the impeller 26 rotates, the blades 28 draw fluid from the intake passage of the inlet 22, pressurize it, and direct it through an outlet 34.

[0021] A drive section 36 includes a motor for driving the impeller 26. In some embodiments, the drive section 36 includes gears between the motor and the impeller 26 to selectively control the speed of rotation of the impeller 26.

[0022] A plurality of swirl nozzles 40 have outlets that introduce fluid, which is schematically shown at 42, into the intake passage of the inlet 22. The outlets of the swirl nozzles 40 are situated in the intake passage downstream of the inlet guide vanes 24 and upstream of the impeller 26. For example, the plurality of swirl nozzles 40 may be equidistantly (or approximately) spaced around a circumference of the intake passage of the inlet 22. The swirl nozzles 40 introduce a desired swirl in the fluid within the portion or section of the intake passage that is between the inlet guide vanes 24 and the impeller 26.

[0023] The swirl nozzles 40 receive pressurized fluid, such as refrigerant, from the outlet 34. In the illustrated example embodiment, a nozzle supply conduit or manifold 44 provides the fluid to the swirl nozzles 40. The nozzle supply conduit or manifold 44 includes at least one control valve 46. A controller 50, which includes a computing device such as a microprocessor, controls operation of the control valve 46 to regulate how much fluid is introduced to achieve a desired amount of swirl in the intake passage upstream of the impeller 26.

[0024] The outlets of the swirl nozzles 40 are between the inlet guide vanes 24 and the impeller 26 to ensure a desired swirl of fluid encountering the leading edges of the blades 28 of the impeller 26. The inlet guide vanes 24 tend to affect characteristics of fluid flow within the intake passage in a manner that results in an increased work input under at least some conditions. This is particularly true during part-load conditions in which the compressor 20 is operating at less than full capacity. For example, the controller 50 may increase the amount of fluid flow through at least one of the plurality of swirl nozzles 40 when the compressor 20 is operating in a part-load condition. The swirl introduced downstream of the inlet guide vanes 24 by the swirl nozzles 40 compensates for or negates any undesired or negative effect of the inlet guide vanes 24. The swirl introduced by the swirl nozzles 40 controls the incidence angle of the fluid encountering the leading edges of the blades 28, which results in less work input and increased compressor efficiency.

[0025] The controller 50 is configured or programmed to control operation of the swirl nozzles 40 to achieve desired swirl and interaction between the impeller blades 28 and the fluid encountering the leading edges of the blades 28. For example, the controller 50 receives information regarding the operating condition of the compressor 20 and determines how much, if any, swirl is needed to achieve or approach a desired compressor efficiency.

[0026] Figure 2 schematically illustrates one of the swirl nozzles 40. In this example embodiment, each swirl nozzle 40 has an associated control valve 46 so that each swirl nozzle 40 is individually controllable. In other embodiments, a control valve 46 controls fluid flow through more than one of the swirl nozzles 40 at a time.

[0027] The controller 50 controls the valve 46 to achieve a desired amount of flow through the swirl nozzle 40 to contribute or establish the desired swirl upstream of the impeller 26. In embodiments where the amount of fluid flow through the swirl nozzle 40 corresponds to or is proportional to the amount of swirl in the intake passage, the controller 50 causes the valve 46 to allow fluid to flow through the swirl nozzle 40 in an amount that will result in the desired swirl.

[0028] The outlet of the swirl nozzle 40 has an adjustable outlet direction to vary the way in which fluid is introduced by the swirl nozzle 40 into the intake passage. The outlet direction is varied in this example by changing the orientation or position of the nozzle outlet relative to the intake passage. The outlet end of the swirl nozzle 40 can be moved into more than one oblique angle relative to the primary flow direction 52 within the intake passage of the inlet 22. The controller 50 adjusts the position or orientation as may be needed to achieve a desired swirl by causing an actuator (not shown) to change the position or orientation from that shown in solid lines to that shown in broken lines in Figure 2. In another embodiment, the swirl nozzle outlet includes an internal deflector or vane that may be adjusted to control the direction of fluid exiting the swirl nozzle.

[0029] The controller 50 controls the swirl nozzles 40 to achieve swirl in the intake passage downstream of the inlet guide vanes 24 and upstream of the impeller 26 to ensure a desired characteristic of fluid encountering the leading edges of the impeller blades 28. The swirl resulting from fluid introduced by the swirl nozzles 40 provides a desired incidence angle of the fluid encountering the impeller blades 28 along at least some of the length of the leading edges of the blades 28 between the hub 30 and the shroud 32. In some embodiments, a desired incidence angle is achieved along substantially all of the length of the leading edges of the blades 28.

[0030] The swirl introduced upstream of the impeller 26 in some embodiments results in different flow angles at different portions of the leading edges. In other words, the swirl introduced by the swirl nozzles 40 varies the incidence angle along the leading edges of the impeller blades 28 so that the incidence angle is different for different portions of the leading edges. Optimizing the flow angle at different spanwise locations of the impeller blades 28 contributes to or achieves improved compressor efficiency and surge margin for a variety of operating conditions.

[0031] Another characteristic that can be controlled or optimized through operation of the swirl nozzles 40 is the pressure ratio at the impeller.

[0032] The swirl introduced by the swirl nozzles 40 contributes to or achieves greater compressor efficiency even in conditions such as part-load conditions. Including swirl nozzles 40 downstream of the inlet guide vanes 24 and upstream of the impeller 26 allows for realizing the benefits of inlet guide vanes while avoiding any downside that may be associated with inlet guide vanes under a variety of operating conditions.

[0033] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the scope of this invention as defined by the claims. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims

1. A compressor (20), comprising: an inlet (22) defining an intake passage; a plurality of swirl nozzles (40); a plurality of inlet guide vanes (24) within the intake passage, fluid flow through the plurality of inlet guide vanes into the intake passage being selectively adjustable to control fluid flow through at least a portion of the intake passage downstream of the swirl nozzles; and an impeller (26) including a plurality of blades (28), the impeller directing fluid from the intake passage toward an outlet (34), wherein the plurality of swirl nozzles (40) have outlets positioned downstream of the plurality of inlet guide vanes (24) and upstream of the impeller, the plurality of swirl nozzles being configured to introduce fluid into the intake passage to cause a swirl of fluid in the intake passage between the plurality of inlet guide vanes and the impeller (26); wherein the plurality of blades have leading edges extending between a hub (30) at a center of the impeller (26) and a shroud (32) at an outer boundary of the impeller, the compressor is characterised in that each swirl nozzle (40) of the plurality of swirl nozzles has: a fluid inlet that receives pressurized fluid from the outlet (34), and a fluid outlet (42) configured to introduce fluid into the intake passage, the fluid outlet having a selectively adjustable outlet direction, and the swirl of fluid introduced by the plurality of swirl nozzles (40) controls an incidence angle of fluid encountering the leading edges of the plurality of blades (28).

2. The compressor of claim 1, comprising at least one control valve (46) that controls an amount of the received fluid that is introduced into the intake passage.

3. The compressor of claim 2, wherein the at least one control valve (46) controls the amount of the fluid from the outlet (34) provided to more than one of the plurality of swirl nozzles (40).

4. The compressor of claim 2 or 3, wherein the at least one control valve (46) comprises a plurality of control valves and each of the plurality of swirl nozzles (40) is associated with one of the plurality of control valves.

5. The compressor of any preceding claim, wherein the outlet direction of fluid introduction into the intake passage from the fluid outlets is varied by changing an orientation or position of the fluid outlets relative to the intake passage.

6. The compressor of any preceding claim, wherein the plurality of swirl nozzles (40) are equidistantly spaced around a circumference of the intake passage.

7. The compressor of any preceding claim, comprising a controller (50) that controls at least one of an amount of fluid flowing through the plurality of swirl nozzles (40) and a direction of fluid flow from the plurality of swirl nozzles.

8. The compressor of claim 7, wherein the controller (50) controls a flow rate of fluid upstream of the impeller (26).

9. The compressor of claim 7 or 8, wherein the controller (50) controls the incidence angle of fluid flow onto the blades (28) of the impeller (26).

10. The compressor of claim 7, 8, or 9, wherein the controller (50) determines when the compressor (20) operates in a part-load condition and controls at least one of the amount of fluid flow through the plurality of swirl nozzles (40) and the direction of fluid flow from the plurality of swirl nozzles based on the part-load condition.

11. The compressor of claim 10, wherein the controller (50) increases the amount of fluid flow through at least one of the plurality of swirl nozzles (40) when the compressor (20) operates in the part-load condition.

12. The compressor of claim 10 or 11, wherein the controller (50) increases the amount of fluid flow through all of the plurality of swirl nozzles (40) when the compressor (20) operates in the part-load condition.

13. The compressor of any preceding claim, including a controller (50) that controls the incidence angle of fluid flow onto the blades, and wherein the swirl of fluid in the intake passage caused by the plurality of swirl nozzles (40) establishes the incidence angle of fluid encountering the impeller blades (28) along at least a portion of the leading edge of the blades that achieves a selected compressor efficiency, and wherein the controller is configured to optimize the incidence angle for each location along a length of the leading edge of the blades (28).

14. The compressor of claim 13, wherein the leading edges of the blades (28) have a length between the hub (30) and the shroud (32), and the established incidence angle varies along the length of the leading edges of the blades (28).

15. The compressor of any preceding claim, wherein the fluid outlet of each swirl nozzle (40) is moveable into a plurality of oblique angles relative to a primary flow direction (52) within the intake passage of the inlet (22).