Impeller with offset splitter blades

Abstract

An impeller includes a hub mountable to a rotary shaft and configured to rotate about a center axis. The impeller may include a plurality of main blades and splitter blades arranged equidistantly and circumferentially about the center axis. A splitter blade having a leading edge and a trailing edge may be positioned between first and second adjacent main blades and canted such that the leading edge is displaced from a blade position equidistant the first and second adjacent main blades a first percentage amount of one half an angular distance between the first and second adjacent main blades. The trailing edge may be displaced from the blade position equidistant the first and second adjacent main blades a second percentage amount of one half the angular distance between the first and second adjacent main blades. The second percentage amount may be greater or less than the first percentage amount.

We claim: 
     
         1 . An impeller for a compressor, comprising:
 a hub mountable to a rotary shaft of the compressor and configured to rotate about a center axis, the hub comprising a first meridional end portion and a second meridional end portion;   a plurality of main blades mounted to or integral with the hub, the plurality of main blades arranged equidistantly and circumferentially about the center axis; and   a plurality of splitter blades mounted to or integral with the hub, the plurality of splitter blades arranged equidistantly and circumferentially about the center axis, each splitter blade comprising a leading edge meridionally spaced from the first meridional end portion and a trailing edge proximal the second meridional end portion,   wherein a splitter blade is positioned between a first adjacent main blade and a second adjacent main blade and canted such that the leading edge of the splitter blade is displaced from a blade position equidistant the first adjacent main blade and the second adjacent main blade a first percentage amount of one half an angular distance between the first adjacent main blade and the second adjacent main blade, and the trailing edge of the splitter blade is displaced from the blade position equidistant the first adjacent main blade and the second adjacent main blade a second percentage amount of one half the angular distance between the first adjacent main blade and the second adjacent main blade, the second percentage amount being greater or less than the first percentage amount.   
     
     
         2 . The impeller of  claim 1 , wherein the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade such that the splitter blade is circumferentially offset from the blade position equidistant the first adjacent main blade and the second adjacent main blade. 
     
     
         3 . The impeller of  claim 1 , wherein each main blade of the plurality of main blades comprises:
 a leading edge proximal the first meridional end portion;   a trailing edge proximal the second meridional end portion;   a pressure surface side extending between the leading edge and the trailing edge; and   a suction surface side opposing the pressure surface side and extending between the leading edge and the trailing edge,   wherein the splitter blade is positioned between a pressure surface side of the first adjacent main blade and a suction surface side of the second adjacent main blade such that the splitter blade is circumferentially offset from the blade position equidistant the first adjacent main blade and the second adjacent main blade.   
     
     
         4 . The impeller of  claim 3 , wherein the splitter blade is circumferentially offset in a direction toward the pressure surface side of the first adjacent main blade. 
     
     
         5 . The impeller of  claim 3 , wherein:
 a first flow passage is formed between the splitter blade and the pressure surface side of the first adjacent main blade; and   a second flow passage is formed between the splitter blade and the suction surface side of the second adjacent main blade, such that the first flow passage and the second flow passage are configured to receive substantially equal mass flow therethrough.   
     
     
         6 . The impeller of  claim 5 , wherein the splitter blade comprises:
 a pressure surface side extending between the leading edge and the trailing edge of the splitter blade; and   a suction surface side opposing the pressure surface side and extending between the leading edge and the trailing edge of the splitter blade,   wherein the first flow passage is formed between the suction surface side of the splitter blade and the pressure surface side of the first adjacent main blade, and the second flow passage is formed between the pressure surface side of the splitter blade and the suction surface side of the second adjacent main blade.   
     
     
         7 . The impeller of  claim 1 , wherein the plurality of main blades and the plurality of splitter blades are equal in number. 
     
     
         8 . The impeller of  claim 1 , wherein the respective leading edges of the main blades and the respective leading edges of the splitter blades are arranged in an meridionally-staggered pattern with respect to one another. 
     
     
         9 . The impeller of  claim 1 , wherein the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade and canted such that the second percentage amount is greater than the first percentage amount. 
     
     
         10 . The impeller of  claim 1 , wherein the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade and canted such that the second percentage amount is less than the first percentage amount. 
     
     
         11 . A compressor comprising:
 a housing;   an inlet coupled to or integral with the housing and defining an inlet passageway configured to receive and flow a process fluid;   a rotary shaft configured to be driven by a driver;   a centrifugal impeller coupled with the rotary shaft and fluidly coupled to the inlet passageway, the centrifugal impeller configured to rotate about a center axis and impart energy to the process fluid received via the inlet passageway, the centrifugal impeller comprising:
 a hub defining a borehole through which a coupling member or the rotary shaft of the compressor extends, the hub comprising a first meridional end portion having an annular portion and a second meridional end portion forming a disc-shaped portion; and 
 a plurality of blades mounted to or integral with the hub, the plurality of blades arranged equidistantly and circumferentially about the center axis and comprising a splitter blade positioned between a first adjacent main blade and a second adjacent main blade and canted with respect to the first adjacent main blade and the second adjacent main blade; 
   a static diffuser circumferentially disposed about the centrifugal impeller and configured to receive the process fluid from the centrifugal impeller and convert the energy imparted to pressure energy; and   a collector fluidly coupled to and configured to collect the process fluid exiting the static diffuser,   wherein the compressor is configured to provide a compression ratio of at least about 8:1.   
     
     
         12 . The compressor of  claim 11 , wherein:
 the splitter blade comprises a leading edge meridionally spaced from the first meridional end portion and a trailing edge proximal the second meridional end portion, and   the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade and canted such that the leading edge of the splitter blade is displaced from a blade position equidistant the first adjacent main blade and the second adjacent main blade a first percentage amount of one half an angular distance between the first adjacent main blade and the second adjacent main blade, and the trailing edge of the splitter blade is displaced from the blade position equidistant the first adjacent main blade and the second adjacent main blade a second percentage amount of one half the angular distance between the first adjacent main blade and the second adjacent main blade, the second percentage amount being greater or less than the first percentage amount.   
     
     
         13 . The compressor of  claim 11 , wherein the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade such that the splitter blade is circumferentially offset from the blade position equidistant the first adjacent main blade and the second adjacent main blade. 
     
     
         14 . The compressor of  claim 11 , wherein each main blade of the plurality of main blades comprises:
 a leading edge proximal the first meridional end;   a trailing edge proximal the second meridional end;   a pressure surface side extending from the leading edge to the trailing edge; and   a suction surface side opposing the pressure surface side and extending from the leading edge to the trailing edge,   wherein the splitter blade is positioned between a pressure surface side of the first adjacent main blade and a suction side surface of the second adjacent main blade such that the splitter blade is circumferentially offset from the blade position equidistant the first adjacent main blade and the second adjacent main blade.   
     
     
         15 . The compressor of  claim 14 , wherein the splitter blade is circumferentially offset in a direction toward the pressure surface side of the first adjacent main blade. 
     
     
         16 . The compressor of  claim 14 , wherein:
 a first flow passage is formed between the splitter blade and the pressure surface side of the first adjacent main blade; and   a second flow passage is formed between the splitter blade and the suction surface side of the second adjacent main blade, such that the first flow passage and the second flow passage are configured to receive substantially equal mass flow therethrough.   
     
     
         17 . The compressor of  claim 11 , wherein:
 the process fluid comprises carbon dioxide;   the compressor is configured to provide a compression ratio of at least about 10:1; and   the second meridional end portion of the centrifugal impeller is configured to discharge the process fluid therefrom in at least a partially radial direction at an absolute Mach number of about 1.3 or greater.   
     
     
         18 . The compressor of  claim 17 , wherein the centrifugal impeller is configured to rotate via the rotary shaft at a rotational speed of about 500 meters per second or greater. 
     
     
         19 . A compression system comprising:
 a driver comprising a drive shaft, the driver configured to provide the drive shaft with rotational energy;   a supersonic compressor operatively coupled to the driver via a rotary shaft integral with or coupled with the drive shaft and configured to rotate about a center axis, the supersonic compressor comprising:
 a compressor chassis; 
 an inlet defining an inlet passageway configured to flow a process fluid therethrough, the process fluid having a first velocity and a first pressure energy; 
 a centrifugal impeller coupled with the rotary shaft and fluidly coupled to the inlet passageway, the centrifugal impeller having a tip and configured to increase the first velocity and the first pressure energy of the process fluid received via the inlet passageway and discharge the process fluid from the tip in at least a partially radial direction having a second velocity and a second pressure energy, the second velocity being a supersonic velocity having an absolute Mach number of about one or greater, wherein the centrifugal impeller comprises:
 a hub defining a borehole through which a coupling member or the rotary shaft of the supersonic compressor extends, the hub comprising a first meridional end portion having an annular portion and a second meridional end portion forming the tip; and 
 a plurality of blades mounted to or integral with the hub, the plurality of blades arranged equidistantly and circumferentially about the center axis and comprising a splitter blade positioned between a first adjacent main blade and a second adjacent main blade and canted with respect to the first adjacent main blade and the second adjacent main blade; 
 
 a static diffuser circumferentially disposed about the tip of the centrifugal impeller and defining an annular diffuser passageway configured to receive and reduce the second velocity of the process fluid to a third velocity and increase the second pressure energy to a third pressure energy, the third velocity being a subsonic velocity; and 
 a discharge volute fluidly coupled to the annular diffuser passageway and configured to receive the process fluid flowing therefrom, wherein the supersonic compressor is configured to provide a compression ratio of at least about 8:1. 
   
     
     
         20 . The compression system of  claim 19 , wherein:
 the process fluid comprises carbon dioxide;   the second velocity has an absolute Mach number of about 1.3 or greater;   the supersonic compressor is configured to provide a compression ratio of at least about 10:1; and   the splitter blade is positioned between the first adjacent main blade and the second adjacent main blade such that the splitter blade is circumferentially offset from a blade position equidistant the first adjacent main blade and the second adjacent main blade, the splitter blade being circumferentially offset in a direction toward a pressure surface side of the first adjacent main blade.