Patent Publication Number: US-11655825-B2

Title: Compressor including aerodynamic swirl between inlet guide vanes and impeller blades

Description:
BACKGROUND 
     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. 
     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. 
     SUMMARY 
     An illustrative example embodiment of a compressor includes 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 the 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 
     In addition to one or more of the features described above, or as an alternative, the compressor includes at least one control valve, the plurality of swirl nozzles receive fluid from the outlet, and the at least one control valve controls an amount of the received fluid that is introduced into the intake passage. 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, a direction of fluid introduction into the intake passage from at least some of the swirl nozzles is selectively adjustable to change a characteristic of the swirl of fluid. 
     In addition to one or more of the features described above, or as an alternative, the plurality of swirl nozzles are equidistantly spaced around a circumference of the intake passage 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, the controller controls to control a flow rate of fluid upstream of the impeller. 
     In addition to one or more of the features described above, or as an alternative, the controller controls an incidence angle of fluid flow onto the blades of the impeller. 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, 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. 
     In addition to one or more of the features described above, or as an alternative, the swirl of fluid in the intake passage caused by the plurality of swirl nozzles establishes an incidence angle of fluid encountering the impeller blades along at least a portion of a leading edge of the blades that achieves a selected compressor efficiency. 
     In addition to one or more of the features described above, or as an alternative, the impeller includes a hub at a center of the blades, the impeller includes a shroud near radially outer ends of the blades, 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. 
     In addition to one or more of the features described above, or as an alternative, the established incidence angle is optimized for each location along the length of the leading edge of the blades. 
     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 drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically illustrates an example embodiment of a compressor including aerodynamic pre-swirl. 
         FIG.  2    schematically illustrates an example embodiment of a nozzle and valve configuration. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  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. 
     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 . 
     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 . 
     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 . 
     In the illustrated example embodiment, the swirl nozzles  40  receive pressurized fluid, such as refrigerant, from the outlet  34 . 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 . 
     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, for example, the incidence angle of the fluid encountering the leading edges of the blades  28 , which results in less work input and increased compressor efficiency. 
     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. 
       FIG.  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. 
     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. 
     In this example embodiment, 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  FIG.  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. 
     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 . For example, 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 . 
     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. 
     Another characteristic that can be controlled or optimized through operation of the swirl nozzles  40  is the pressure ratio at the impeller. 
     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 operating conditions. 
     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 essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.