Patent Application
20200325911
Centrifugal compressors are used in rotating machines to pressurize a fluid. A typical centrifugal compressor comprises an impeller coupled to a rotatable shaft. Fluid exiting a rotating impeller is at a high Mach number and dynamic pressure. For certain applications, such as a gas turbine engine having a centrifugal compressor discharging pressurized air to a combustion chamber, the fluid exiting a rotating impeller must be diffused prior to being used in an application.
According to some aspects of the present disclosure, a diffuser assembly is disclosed for conditioning the effluent of a centrifugal compressor. The centrifugal compressor has an axis of rotation. The diffuser assembly comprises an annular conduit, a first set of vanes, and a second set of vanes. The annular conduit comprises a first wall and a second wall, the first and second wall displaced from each other and cooperating to define an inlet, an outlet, and a fluid passage extending from the inlet to the outlet. The fluid passage comprises a first passage portion, a second passage portion, and a third passage portion. The first passage portion extends radially outward from the inlet and defined between a first portion of the first wall and a first portion of the second wall. The first portions of the first and second walls are linear and parallel in axial cross section along the length of the first passage portion. The second passage portion extends from the first passage portion and is defined between a second portion of the first wall and a second portion of the second wall. The second portions of the first and second walls are curved in an axial dimension in axial cross section. The third passage portion extends from the second passage portion and is defined between a third portion of the first wall and a third portion of the second wall. The third portions of the first and second wall are linear in axial cross section and spaced apart at an increasing distance along the length of the third passage portion. The first set of vanes are positioned in the first passage portion. The second set of vanes are positioned in the second passage portion. Each of the vanes of the second set of vanes comprises a pressure surface and a suction surface extending from a leading edge to a trailing edge of the vane. The pressure and suction surfaces each curve in an axial and lateral dimension.
In some embodiments each of the vanes of the first set of vanes curve in a lateral dimension. In some embodiments each of the vanes of the first set of vanes curve about a respective radius extending perpendicular to the axis of rotation. In some embodiments the second portions of the first and second walls are spaced apart by the same distance along the length of the second passage portion. In some embodiments the second portions of the first and second walls are spaced apart at a decreasing distance along the length of the second passage portion.
In some embodiments the inlet is positioned to receive the effluent of the centrifugal compressor. In some embodiments the outlet is positioned to direct fluid exiting the deswirler assembly to a combustion chamber. In some embodiments one or more vanes of the second set of vanes have a length greater than two thirds of the length of the second passage portion. In some embodiments one or more vanes of the first set of vanes have a length greater than three quarters of the length of the first passage portion.
According to further aspects of the present disclosure, a diffuser assembly is disclosed for conditioning the effluent of a centrifugal compressor having an axis of rotation. The diffuser assembly comprises an annular conduit, a first set of vanes, and a second set of vanes. The annular conduit comprises a first wall and a second wall displaced from each other and cooperating to define an inlet, an outlet, and a passage extending from the inlet to the outlet. The passage comprises a first linear portion, a curved portion, and a second linear portion. The first set of vanes are positioned in the first linear portion of the passage. The first linear portion is defined between radially extending portions of the first wall and second wall. Each vane of the first set of vanes curves from a first leading edge to a first trailing edge. The second set of vanes are positioned in the curved portion of the passage. The curved portion is defined by an axially aft curve of the first and second walls. Each vane of the second set of vanes curves axially and laterally from a second leading edge facing the linear portion of the passage to a second trailing edge.
In some embodiments each vane of the first set of vanes curves about a respective radius extending perpendicular to the axis of rotation. In some embodiments each vane of the first set of vanes curves laterally from the first leading edge facing the inlet to the first trailing edge facing the curved portion of the passage. In some embodiments the second linear portion is defined between portions of the first and second wall being linear in axial cross section and spaced apart at an increasing distance along the length of the second linear portion. In some embodiments the second linear portion is defined between portions of the first and second wall being linear and parallel in axial cross section.
According to still further aspects of the present disclosure, a method is disclosed for conditioning a fluid exiting a centrifugal compressor having an axis of rotation. The method comprises passing the fluid through a first linear portion of an annular conduit, the first linear portion defined between radially extending and parallel portions of a first conduit wall and a second conduit wall, the first linear portion comprising a plurality of first vanes extending between the first conduit wall to the second conduit wall; and passing the fluid through a curved portion of the annular conduit after the fluid is passed through the first linear portion, the curved portion defined between axially curved portions of the first conduit wall and the second conduit wall, the curved portion comprising a plurality of second vanes extending between the first conduit wall and the second conduit wall, wherein each vane of the plurality of second vanes curves in an axial and a lateral dimension.
In some embodiments the method further comprises passing the fluid through a flared portion of the annular conduit after the fluid is passed through the curved portion, the flared portion defined between linear portions of the first conduit wall and the second conduit wall spaced apart at an increasing distance along the length of the flared portion. In some embodiments the method further comprises passing the fluid through a second linear portion of the annular conduit after the fluid is passed through the curved portion, the second linear portion defined between linear portions of the first conduit wall and the second conduit wall spaced apart at the same distance along the length of the second linear portion.
In some embodiments the method further comprises discharging the fluid to a combustion chamber after the fluid is passed through the first linear portion and the curved portion. In some embodiments the method further comprises discharging the fluid from the centrifugal compressor in a radially outward direction prior to passing the fluid through the first linear portion. In some embodiments the method further comprises positioning the first linear portion to receive the effluent of a centrifugal compressor.
The following will be apparent from elements of the figures, which are provided for illustrative purposes.
The present application discloses illustrative (i.e., example) embodiments. The claimed inventions are not limited to the illustrative embodiments. Therefore, many implementations of the claims will be different than the illustrative embodiments. Various modifications can be made to the claimed inventions without departing from the spirit and scope of the disclosure. The claims are intended to cover implementations with such modifications.
For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments in the drawings and specific language will be used to describe the same.
A typical diffuser used to slow the velocity of a fluid exiting a centrifugal compressor comprises a set of static vanes positioned at the outlet of the centrifugal compressor, a flowpath turn from a generally radial direction to a generally axial direction, and a set of deswirl vanes. Since space in modern rotating machines such as gas turbine engines is at a premium, advances are desired to sufficiently diffuse the fluid exiting a centrifugal compressor while reducing the space requirements of the diffuser.
The present disclosure is therefore directed to systems and methods of diffusing and/or deswirling a fluid exiting from a centrifugal compressor while reducing the space requirements or footprint of the diffuser. More specifically, the present disclosure is generally directed to a diffuser of a centrifugal compressor having a first set of vanes positioned in a radial portion of the diffuser conduit and a second set of vanes positioned in a turn of the diffuser conduit.
Centrifugal compressor 102 may comprise an impeller 104 affixed to a rotatable shaft 108 that defines an axis of rotation A. A plurality of blades 106 may extend radially outward from the impeller 104. The centrifugal compressor 102 may further comprise a shroud 110 that at least partly encases the impeller 104. During operation, fluid flows into the centrifugal compressor 102 at a compressor inlet 112, between the rotating blades 106, and exits the centrifugal compressor 102 at a compressor outlet 114. The centrifugal compressor 102 may be part of a larger rotatable machine, such as a gas turbine engine.
A diffuser assembly 200 may be positioned to receive the effluent of the centrifugal compressor 102. The diffuser assembly 200 may condition or treat the effluent, or fluid discharged from the centrifugal compressor 102. The diffuser assembly 200 may comprise an annular conduit 201 and two sets of vanes 231, 233 positioned in the conduit 201.
The annular conduit 201 may comprise a first wall 203 and a second wall 205. First wall 203 and second wall 205 may be annular. First wall 203 and second wall 205 are displaced from each other and may together define a fluid passage 211. First wall 203 and second wall 205 may be axially displaced from each other. First wall 203 and second wall 205 may define a diffuser inlet 207 and diffuser outlet 209. The fluid passage 211 may extend from the diffuser inlet 207 to the diffuser outlet 209.
The annular conduit 201 may be positioned to receive fluid discharged in a radial direction from the centrifugal compressor 102. The diffuser inlet 207 may be adjacent the compressor outlet 114. The annular conduit 201 may be positioned with the diffuser inlet 207 radially outward of the compressor outlet 114. The annular conduit 201 may be positioned to receive the effluent of the centrifugal compressor 102.
The fluid passage 211 may comprise three passage portions. A first passage portion 213, also referred to as a linear portion or first linear portion, may extend radially outward from the diffuser inlet 207 and may be defined between a first portion 219 of the first wall 203 and a first portion 221 of the second wall 205. As shown in
A first set of vanes 231 may be positioned in the first passage portion 213. In some embodiments, each vane of the first set of vanes 231 may curve in a lateral dimension. In some embodiments, each vane of the first set of vanes 231 may curve about a radius extending perpendicular to the axis of rotation A. The first set of vanes 231 may be referred to as diffuser vanes. One or more vanes of the first set of vanes 231 may have a length that is greater than half of the length of the first passage portion 213. In some embodiments, one or more vanes of the first set of vanes 231 may have a length that is greater than three quarters of the length of the first passage portion 213.
A second passage portion 215 or curved portion may extend from the first passage portion 213. The second passage portion 215 may be defined between a second portion 223 of the first wall 203 and a second portion 225 of the second wall 205. As shown in
A second set of vanes 233 may be positioned in the second passage portion 215.
A third passage portion 217 may extend from the second passage portion 215 and may be referred to as a flared portion or a second linear portion. The third passage portion 217 may be defined between a third portion 227 of the first wall 203 and a third portion 229 of the second wall 205. The third portions 227, 229 may be linear in axial cross section. In some embodiments, the third portions 227, 229 may be spaced apart at the same distance along the length of the third passage portion 217. As shown in
The deswirler assembly 202 may comprise the second passage portion 215 and the third passage portion 217.
Following the third passage portion 217, the annular conduit 201 may terminate with a diffuser outlet 209. The diffuser outlet 209 may discharge conditioned effluent of a centrifugal compressor 102. The diffuser outlet 209 may discharge a fluid conditioned by one or both of the first set of vanes 231 and second set of vanes 233 after the fluid was discharged by the centrifugal compressor 102. The diffuser outlet 209 may be positioned to discharge fluid exiting the diffuser assembly 200 to a combustion chamber, or to another application.
The present disclosure additional provides methods of conditioning or treating the effluent of a centrifugal compressor 102. One such method 600 is presented in the flow diagram of
At Block 603 fluid may be discharged from a centrifugal compressor 102. The fluid may exit the centrifugal compressor 102 at a compressor outlet 114. The fluid may exit the centrifugal compressor 102 in a radially outward direction. The fluid may enter a diffuser assembly 200 upon discharge from the centrifugal compressor 102. The step performed at Block 603 may further comprise positioning a first linear portion 213 of an annular conduit 201 of a diffuser assembly 200 to receive fluid exiting from a centrifugal compressor 102.
At Block 605 the fluid exiting the centrifugal compressor 102 may be passed through a first linear portion 213 of an annular conduit 201 of a diffuser assembly 200. The first linear portion 213 may be defined between radially extending and parallel portions 219, 221 in axial cross section of a first conduit wall 203 and a second conduit wall 205. The first linear portion 213 may comprise a plurality of first vanes 231 extending between the first conduit wall 203 and the second conduit wall 205. Each vane of the first set of vanes 231 may curve in a lateral dimension or may curve about a radius extending perpendicular to the axis of rotation A. One or more vanes of the first set of vanes 231 may have a length that is greater than half of or three quarters of the length of the first passage portion 213.
At Block 607 the fluid may be passed through a curved portion 215 of the annular conduit 201 after the fluid is passed through the first linear portion 213. The curved portion 215 may be defined between axially curved portions 223, 225 of said first conduit wall 203 and said second conduit wall 205. The curved portion 215 may comprise a plurality of second vanes 233 extending between the first conduit wall 203 and the second conduit wall 205. Each vane of the plurality of second vanes 233 may curve in an axial and a lateral dimension. Each vane of the second set of vanes 233 may comprise a pressure surface 342 and a suction surface 344 each extending from a leading edge 346 to a trailing edge 348. The pressure surface 342 and suction surface 344 of each vane of the second set of vanes 233 may curve in an axial and lateral dimension. One or more vanes of the second set of vanes 233 may have a length that is greater than half of or two thirds of the length of the second passage portion 215.
At Block 609 the fluid may be passed through a flared portion 217 of the annular conduit 201 after the fluid is passed through the curved portion 215. The flared portion 217 may be defined between linear portions 227, 229 of said first conduit wall 203 and said second conduit wall 205. The linear portions 227, 229 may be spaced apart at an increasing distance in axial cross section along the length of the flared portion 217. In some embodiments the step at Block 609 may be performed by passing the fluid through a second linear portion rather than a flared portion. The second linear portion may be defined between linear portions 227, 229 that are parallel in axial cross section.
At Block 611 the fluid may be discharged from the annular conduit 201 and/or the diffuser assembly 200. The fluid may be discharged to a combustion chamber. The fluid may be discharged after the fluid is passed through the first linear portion 213 and the curved portion 215.
Method 600 ends at Block 613.
The disclosed diffuser assembly 200 may be manufactured as more than one constituent pieces, or may be cast as a single piece for multiple constituent pieces.
The presently disclosed systems and methods provide advantages over prior art systems and methods of diffusing and/or deswirling fluid exiting a centrifugal compressor. Notably, the presently disclosed diffuser assembly occupies less space, particularly in an axial dimension, than prior art systems. While maintaining similar diffusing and/or deswirling properties, the presently disclosed systems and methods free space that may allow for a smaller overall engine, alternative uses for the space, and/or a lighter overall engine. Bringing the deswirler vanes forward into the turn of the diffuser assembly frees additional space to include a third passage portion that reduces dump losses in the system. These reduced dump losses may be sufficient to offset any increases in losses through the deswirler vanes themselves.
Although examples are illustrated and described herein, embodiments are nevertheless not limited to the details shown, since various modifications and structural changes may be made therein by those of ordinary skill within the scope and range of equivalents of the claims.
