Axial flow turbo compressor

Abstract

An axial flow compressor including one or more axially spaced stator sections ( 14 ) each having a circumferential array of guide vanes ( 15 ), and one or more rotor section (12, 16) each having a circumferential array of rotor blades ( 13, 17; A, B), and between successive rotor blades (A, B) there are formed flow paths and between the stator and rotor sections there are provided axial gaps ( 22, 23, 24 ) of a diverging configuration so as to form in each flow path a diffusion region (C) which extends from a narrowest cross section (a 2 ) of the flow path located at a certain distance upstream of the leading edge of a second rotor blade (B) to a wider cross section (a 3 ) located approximately at the leading edge of the second rotor blade (B), wherein each flow path has a transition region (D) of a substantially non-increasing cross sectional area extending from the wider cross section (a 3 ) to the trailing edges of the rotor blades (A, B).

1 . Axial flow turbine compressor, comprising a stator with at least one axial section including a circumferential array of flow directing guide vanes ( 13 , 17 ), a rotor with at least one axial section including a circumferential array of rotor blades ( 15 ; A, B), an inner peripheral wall ( 28 ), and an outer peripheral wall ( 29 ), wherein a flow path is formed between every two successive rotor blades (A,B) in the direction of rotor rotation (ω) and between said inner and outer peripheral walls ( 28 , 29 ), characterized in that each flow path comprises 
 a narrowest cross sectional area at a first cross section (a 2 ) located at a certain distance upstream of the leading edge of a second rotor blade (B) in the direction of rotor rotation (ω),    a diffusion region (C) having a successively increasing cross sectional area in the flow direction and extending from said first cross section (a 2 ) to a second cross section (a 3 ) located approximately at the leading edge of said second rotor blade (B), and    a transition region (D) extending in the flow direction from said second cross section (a 3 ) to the trailing edge of said second rotor blade (B), said transition region (D) has a substantially non-increasing cross sectional area in the flow direction throughout its length.    
   
   
       2 . Turbine compressor according to  claim 1 , wherein the transverse distance between said first and second rotor blades (A,B) increases throughout said transition region (D), whereas the radial distance between said inner peripheral wall ( 28 ) and said outer peripheral wall ( 29 ) decreases such that the cross sectional area of the flow path does not increase throughout said transition region (D).  
   
   
       3 . Turbine compressor according to  claim 1  or  2 , wherein the flow through said diffusion region (C) is substantially laminar.  
   
   
       4 . Turbine compressor according to anyone of claims  1 - 3 , wherein each flow path upstream of said diffusion region (C) has a substantially constant cross sectional area.  
   
   
       5 . Axial flow type turbine compressor, comprising a stator with at least one circumferential row of flow directing guide vanes. ( 13 , 17 ), and a rotor with at least one circumferential row of rotor blades ( 15 ; A,B), wherein between said guide vanes ( 13 , 17 ) and said rotor blades ( 15 ; A,B) there are formed a number of parallel flow paths, and between successive rotor blades (A,B) there are formed rotor flow passages through which said flow paths extend, characterized in that each flow path has a diffusion region (C) extending from a location approximately at the leading edge of a first one (A) of said successive rotor blades (A,B) to a location approximately at the leading edge of a second rotor blade (B) in the rotation direction (ω) of said rotor, wherein each one of said rotor flow passages downstream of said diffusion region (C) has a substantially non-increasing cross sectional area throughout its length.  
   
   
       6 . Turbine compressor according to  claim 5 , wherein said flow paths as well as said rotor flow passages are partly defined by an outer peripheral wall ( 29 ) and an inner peripheral wall ( 28 ).  
   
   
       7 . Turbine compressor according to  claim 5  or  6 , wherein each one of said rotor flow passages is defined by a first rotor blade (A), and a second rotor blade (B) succeeding said first rotor blade (A) in the direction of rotor rotation (ω), said diffusion region (D) extends in the flow direction from a location approximately at the leading edge of said first rotor blade (A) to a location approximately at the leading edge of said second rotor blade (B), and each one of said flow paths has a narrowest cross sectional area (a 2 ) at the upstream end of said diffusion region (C).  
   
   
       8 . Turbine compressor according to  claim 1 , wherein said guide vanes ( 13 , 17 ) are arranged in two or more axially spaced stator sections, and said rotor blades ( 15 ) are arranged in two or more axially spaced rotor sections, 
 said rotor sections and said stator sections are arranged with an axial gap ( 22 , 23 , 24 ) between them,    said axial gap ( 22 , 23 , 24 ) having an axial width of at least 30% of the chord length of the preceding guide vane ( 13 , 17 ) or rotor blade ( 15 ), and    said axial gap ( 22 , 23 , 24 ) forms a flow passage region with a,radially diverging shape in the axial direction.    
   
   
       9 . Turbine compressor according to  claim 8 , wherein said flow passage region has a radial extent (h 2 ) at its downstream end that is at least 10% larger than the radial extent (h 1 ) at its upstream end.  
   
   
       10 . Turbine compressor according to  claim 8 , wherein said flow passage region has an axial width of at least 50% of the chord length of the preceding guide vane ( 13 , 17 ) or rotor blade ( 15 ).