Method of improving the flow conditions in an axial-flow compressor, and axial-flow compressor for carrying out the method

Abstract

In a method of improving the flow conditions on the suction side ( 21 ) of the blade ( 12 ) of an axial-flow compressor ( 10 ) provided for compressing air, in which method vortices running in the direction of flow are generated on the suction side ( 21 ), a marked improvement is achieved in a simple and reliable manner by the vortices being generated by local air jets ( 18 ) formed on the suction side ( 21 ).

1 . A method of improving the flow conditions on the suction side of the blade of an axial-flow compressor provided for compressing air, in which method vortices running in the direction of flow are generated on the suction side, wherein the vortices are generated by local air jets formed on the suction side.  
   
   
       2 . The method as claimed in  claim 1 , wherein, to form the local air jets, air having a higher pressure relative to the environment is discharged from first openings in the suction-side surface of the blade.  
   
   
       3 . The method as claimed in  claim 2 , wherein the air having the higher pressure on the pressure side of the blade is extracted from the flow and is directed through the blade to the first openings in the suction-side surface of the blade.  
   
   
       4 . The method as claimed in  claim 3 , wherein a second opening on the pressure side of the blade is assigned to each first opening on the suction side of the blade, and wherein the air having the higher pressure is in each case extracted at the second opening and directed via passages in the blade to the associated first opening.  
   
   
       5 . The method as claimed in  claim 3 , wherein, to increase the pressure of the air extracted at the pressure side, the dynamic pressure associated with the flow is also utilized in addition to the static pressure prevailing on the pressure side.  
   
   
       6 . The method as claimed in  claim 5 , wherein a first passage in the blade is used in order to utilize the dynamic pressure during the extraction of the air, this first passage being inclined in the direction of flow.  
   
   
       7 . An axial-flow compressor for carrying out the method as claimed in  claim 1 , which axial-flow compressor comprises at least one blade ring of blades extending in the radial direction, wherein each of the blades on the suction side has a row of first openings extending in the radial direction, these first openings each being connected to a source for air having a higher pressure.  
   
   
       8 . The axial-flow compressor as claimed in  claim 7 , wherein the first openings are each arranged in the vicinity of the leading edge of the blade.  
   
   
       9 . The axial-flow compressor as claimed in  claim 7 , wherein, as a source for air having a higher pressure, second openings on the pressure side of the blade are assigned to the first openings on the suction side of the blade.  
   
   
       10 . The axial-flow compressor as claimed in  claim 9 , wherein a second opening is assigned to each first opening and is connected to the first opening via passages running transversely through the blade.  
   
   
       11 . The axial-flow compressor as claimed in  claim 10 , wherein in each case a first passage is arranged in the interior of the blade behind the second opening, this first passage running in the direction of flow and enclosing an acute angle, in particular of about 20°, with the pressure-side surface of the blade.  
   
   
       12 . The axial-flow compressor as claimed in  claim 11 , wherein the first passage has a diameter of about 1 mm.  
   
   
       13 . The axial-flow compressor as claimed in  claim 11 , wherein in each case a second passage is arranged in the interior of the blade behind the first opening, this second passage running in the direction of flow and enclosing an acute angle, in particular of about 60°, with the pressure-side surface of the blade.  
   
   
       14 . The axial-flow compressor as claimed in  claim 13 , wherein the second passage is tilted by an angle, preferably of about 45°, from the plane spanned by the first passage and the direction of flow.  
   
   
       15 . The axial-flow compressor as claimed in  claim 13 , wherein the second passage has a diameter of about 0.4 mm.  
   
   
       16 . The axial-flow compressor as claimed in  claim 13 , wherein the first and second passages open into one another in the interior of the blade.  
   
   
       17 . The axial-flow compressor as claimed in  claim 7 , wherein the first openings of each blade are uniformly spaced apart and are at a distance from one another of about 4 mm.