Patent Application
20170284226
The present disclosure generally relates to turbine engine technologies. More particularly, the present disclosure relates to turbine engine designs for improved fine particle (such as sand) separation efficiency.
Turbine engines are used for a number of purposes, including propulsion and/or driving various other components with electrical, pneumatic, and/or hydraulic power, and may include both propulsion engines and auxiliary power units (APUs). Generally, a gas turbine engine includes a compressor section, a combustion section, and a turbine section. During operation, the compressor section draws in ambient air, compresses the air with one or more compressors, and supplies the compressed air to the combustion section. In addition to the compressed air, the combustion section receives fuel via a fuel injection assembly, mixes the fuel with the compressed air, ignites the mixture, and supplies the high energy combustion gases to the turbine section to drive one or more turbines, including a shaft that may be used to drive the compressor and other components.
During operation, the ambient air drawn into the engine may contain undesirable particles, such as sand and dust, which may cause severe performance degradation, excessive wear, increased maintenance, and eventually premature removal of engines. In order to prevent or at least minimize these impacts, many vehicles use an inlet particle separator system, disposed upstream of the engine, to remove at least a portion of the undesirable particles. A conventional inlet particle separator typically includes a duct system having a fluid passageway that transitions into a scavenge flow path and an engine flow path. Air that is induced into the fluid passageway may have particles suspended therein. The inertia of relatively larger ones of the suspended particles tends to cause these particles to travel in a straight line rather than follow the fluid passageway. Because of the manner in which the inlet particle separator is configured, most of the suspended particles tend to flow into the scavenge flow path rather curve into the engine flow path. As such, relatively clean air is directed into the engine, and contaminated air, which has the particles suspended therein, is directed through the scavenge flow path and is discharged.
Conventional inlet particle separators, such as those described above, operate at relatively high efficiencies for relatively large particles (e.g., >20 microns, or <1000 microns). However, for relatively small particles (e.g., <20 microns, or >=1 micron), the efficiencies can be relatively low, resulting in a significant amount of these relatively small particles being ingested into the engine. These relatively small particles can still have some deleterious effects. For example, these particles can plug secondary flow lines and/or can melt and form glass on relatively hot engine components, such as the combustor, which can significantly reduce performance and the operating life of the engines.
Accordingly, there remains a need in the art for improved propulsion turbine engines and APUs. The improved propulsion turbine engines and APUs would exhibit improved particle separation efficiency, particularly with regard to fine sand particles. These engines may implement novel particle separation means that are provided in addition to or as an alternative to conventional inlet particle separators, and may be located at positions within the engine that are different as compared to conventional inlet particle separators. Furthermore, other desirable features and characteristics of the disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.
The present disclosure relates to turbine engine designs, including propulsion engines and APUs, for improved fine particle separation efficiency. These designs may be implemented in addition to or as an alternative to conventional inlet particle separators, which generally separate medium- to large-size particles. In one exemplary embodiment, a turbine engine incorporating a fine particle separation means includes a radial compressor that rotates about a longitudinal axis, and which compresses air fed thereto, a radially-oriented diffuser located downstream and radially outward, with respect to the longitudinal axis, from the radial compressor, and which decreases a velocity of and increases a static pressure of the compressed air exiting the radial compressor, and a flow path positioned downstream and radially outward, with respect to the longitudinal axis, from the diffuser, wherein the flow path comprises an outer annular wall and an inner annular wall between which the compressed air flows, and wherein the flow path comprises an arc that redirects the compressed air from flowing in a substantially radial flow direction to a substantially axial flow direction. The turbine engine also includes an extraction slot in the outer annular wall that fluidly connects with a scavenge plenum, the scavenge plenum being positioned adjacent to and radially outward, with respect to the longitudinal axis, from the outer annular wall at a position downstream axially along the flow path from the arc, the extraction slot also being positioned downstream axially along the flow path from the arc.
In another exemplary embodiment, a turbine engine incorporating a fine particle separation means includes a radial compressor that rotates about a longitudinal axis, and which compresses air fed thereto, a radially-oriented diffuser located downstream and radially outward, with respect to the longitudinal axis, from the radial compressor, and which decreases a velocity of and increases a static pressure of the compressed air exiting the radial compressor, and a flow path positioned downstream and radially outward, with respect to the longitudinal axis, from the diffuser, wherein the flow path comprises an outer annular wall and an inner annular wall between which the compressed air flows, and wherein the flow path comprises an arc that redirects the compressed air from flowing in a substantially radial flow direction to a substantially axial flow direction. The turbine engine further includes a plurality of holes along the outer annular wall that fluidly connect with a second scavenge plenum, the plurality of holes being positioned along the arc, the scavenge plenum being positioned adjacent to and radially outward from, with respect to the longitudinal axis, the arc.
In yet another exemplary embodiment, a turbine engine incorporating a fine particle separation means includes a compressor that rotates about a longitudinal axis, and which compresses air fed thereto and a flow path positioned downstream from the compressor, wherein the flow path comprises an outer annular wall and an inner annular wall between which the compressed air flows, and wherein the flow path comprises an arc the redirects the compressed air from flowing in a substantially radial flow direction to a substantially axial flow direction. The turbine engine also includes either or both of 1) an extraction slot in the outer annular wall that fluidly connects with a first scavenge plenum, the first scavenge plenum being positioned adjacent to and radially outward, with respect to the longitudinal axis, from the outer annular wall at a position downstream axially along the flow path from the arc, the extraction slot also being positioned downstream axially along the flow path from the arc, and 2) a plurality of holes along the outer annular wall that fluidly connect with a second scavenge plenum, the plurality of holes being positioned along the arc, the second scavenge plenum being positioned adjacent to and radially outward from, with respect to the longitudinal axis, the arc.
This brief summary is provided to describe select concepts in a simplified form that are further described in the Detailed Description. This brief summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.
A gas turbine engine may be used to power various types of vehicles and systems. A typical gas turbine engine includes a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section. The fan section induces air from the surrounding environment into the engine and accelerates the air toward the compressor section. The compressor section compresses the pressure of the air to a relatively high level and directs the air to the combustor section. A steady stream of fuel is injected into the combustor section, and the injected fuel is ignited to significantly increase the energy of the compressed air. The high-energy compressed air then flows into and through the turbine section, causing rotationally mounted turbine blades therein to rotate and generate energy. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in the exhaust air, in the case of propulsion turbine engines, aids the thrust generated by the air flowing through a bypass plenum.
In some turbine engines, the compressor section is implemented with a centrifugal compressor. A centrifugal compressor typically includes at least one impeller that is rotationally mounted to a rotor and surrounded by a shroud. When the impeller rotates, it compresses and imparts tangential velocity to the air received from the fan section and the shroud directs the air radially outward into a diffuser. The diffuser decreases the radial and tangential velocity of the air and increases the static pressure of the air and directs the air into a deswirl assembly. The deswirl assembly includes an annular housing having a plurality of straight radially extending vanes mounted therein that straighten and reduce the tangential velocity component of the air flow before it enters the combustor section. The combustor section, in some turbine engines, is implemented with an axial through-flow combustor that includes an annular combustor disposed within a combustor housing that defines a plenum. The straightened air enters the plenum and travels axially through the annular combustor where it is mixed with fuel and ignited.
An exemplary embodiment of a multi-spool, propulsion-type gas turbine engine 100 is depicted in
In the illustrated embodiment, the compressor section 104 includes two compressors: an intermediate pressure compressor 120 and a high pressure compressor 122. Compressors may generally be embodied as radial or mixed flow types. In other embodiments, more or fewer than two compressors may be provided. Returning to
The turbine section 108 includes three turbines disposed in axial flow series, a high pressure turbine 126, an intermediate pressure turbine 128, and a low pressure turbine 130. Here again, in other embodiments, more or fewer than three turbines may be provided. The combusted air from the combustion section 106 expands through each turbine 126, 128, 130, causing each turbine to rotate. The air is then exhausted through a propulsion nozzle 132 (in the case of a propulsion turbine engine) disposed in the exhaust section 110, providing additional forward thrust. As the turbines rotate, each drives equipment in the engine 100 via concentrically disposed shafts or spools. Specifically, in the illustrated embodiment, the high pressure turbine 126 drives the high pressure compressor 122 via a high pressure spool 134, the intermediate pressure turbine 128 drives the intermediate pressure compressor 120 via an intermediate pressure spool 136, and the low pressure turbine 130 drives the fan 112 via a low pressure spool 138.
Turning now to
The diffuser 204 is coupled to the shroud 210 and is configured to decrease the velocity and increase the static pressure of air that is received from impeller 208. In this regard, any one of numerous conventional diffusers 204 suitable for operating with a centrifugal compressor may be employed. In any case, the diffuser 204 includes an inlet 214, an outlet 216, and a flow path 218 that each communicates with the impeller discharge flow passage 212, and the flow path 218 is configured to direct the received air flow radially outward.
The deswirl assembly 206 communicates with the diffuser 204 and is configured to substantially remove swirl from air received therefrom, to thereby decrease the Mach number of the air flow. The deswirl assembly 206 includes an inner annular wall 220, an outer annular wall 222, and pluralities of vanes 224, 226 disposed between the inner annular wall 220 and the outer annular wall 222. The walls 220, 222 define a flow path 228 that is configured to redirect the air from its radially outward direction to a radially inward and axially downstream direction. In this regard, the walls 220, 222 are formed such that the flow path 228 extends between an inlet 230 and outlet 232 in an arc 233 so that when the air exits the outlet 232, it is directed at an angle toward the longitudinal axis 207 and the annular combustor 124. As the angle of the arc 233 is increased the variation of the air angle between the inner wall 220 and out wall 222 is increased.
As noted above, the turbine engine 100 may be configured with an inlet particle separator, located upstream of the compressor section 104, for purposes of efficiently removing relatively large particles (greater than 5 microns, or greater than 20 microns) from the inlet air stream. However, finer particles, such as those smaller than 20 microns, or smaller than 5 microns, may elude the inlet particle separator, and proceed into the turbine engine compressor section 104. Thus, the present disclosure provides additional features, which may be located in the turbine engine compressor section 104, as an alternative or in addition to an inlet particle separator, that serve to efficiently separate any smaller particles from the air stream in the compressor section 104, and thus prevent such smaller particles from entering into the combustor section 106. With continued reference to
Turning now to the first fine particle separation means 300, as detailed in
Accordingly, the first fine particle separation means 300 includes an extraction slot 306 in the outer annular wall that leads to a scavenge plenum 305. The extraction slot 306 may be embodied as a continuous slot, or as a series of holes of any shape or count. The extraction slot is axi-symmetrical, and may encompass from about 1% to about 25%, such as about 1% to about 15%, of the area (along a plane perpendicular to the longitudinal axis 207) of the flow path 228. The extraction slot 306 is located along the deswirl flow path 228 at a position downstream of the arc 233, yet prior to the plurality of vanes 224, 226. The extraction slot 306 should be sized such that bleed air through the extraction slot 306 amounts to less than 5%, such as less than 1% of total air flow, preferably as close to 0% as possible. In one embodiment, the scavenge plenum 305 is located radially outward from the deswirl assembly 206 at a position that is radially adjacent to the first (upstream) plurality of vanes 224. The scavenge plenum 305 includes an inner radial wall 302, an outer radial wall 301, and an axial end wall 303 positioned at an opposite axial (downstream) end of the plenum 305 with respect to the extraction slot 306. It is preferred, as illustrated, that a radius of the outer radial wall 301 that connects with the axial end wall 303 is greater than the radius at which the extraction slot 306 is located, and likewise, it is preferred that a radius of the inner radial wall 302 that connects with the axial end wall 303 is at a lower radius than the radius at which the extraction slot 306 is located, all with respect to the longitudinal axis 207. In the illustrated embodiment, the aforesaid small radially inward component of the flow direction is commenced at the plurality of vanes 224, 226 by the vanes 224, 226 being oriented somewhat radially inward (e.g., about 10 to about 45 degrees). As such, the inner radial wall 302 of the scavenge plenum 305 may also have the same radial declination so as to remain parallel and adjacent to the first plurality of vanes 224, as noted above.
In operation, therefore, the compressed air that exits the diffuser 204 at diffuser outlet 216 will enter the deswirl assembly at inlet 230. Any fine particles in the compressed air, as it passes through the deswirl flow path 228, will tend to track along the arc 233 of outer annular wall 222. Prior to encountering the plurality of vanes 224, 226 (and thus prior to the radial declination at the vanes), the fine particles will be extracted from the flow path 228 at the extraction slot 306 located along the outer annular wall 222, and enter into the scavenge plenum 305. In this manner, the fine particles are efficiently prevented from entering the combustion section 124, which as illustrated, is positioned axially downstream from the second plurality of vanes 226 and deswirl assembly outlet 232. Any fine particle accumulation in the scavenge plenum 305 may be removed from time to time by an appropriate port along any wall of the scavenge plenum 305. For example, the scavenge plenum 305 may also incorporate “smart” particle removal mechanisms, such as an electronically-controlled port(s) connected to an engine exhaust or downstream section of the engine, which can be selectively turned on when needed to actively clean particle accumulation out of the plenum 305 under operating and non-operating conditions.
Referring now to the second fine particle separation means 400, as detailed in
The scavenge plenum 405, connected with the plurality of holes 406, may include an inner radial wall 402, and outer radial wall 401, and an axial end wall 403 positioned at an aft-most (downstream) end of the scavenge plenum 405. The inner radial wall 402 and out the outer radial wall 401 may be contoured or curved to match the curvature of the arc 233, such that each of the plurality of holes 406 extends about the same distance between the deswirl assembly flow path 228 and the scavenge plenum 405. In addition, the scavenge plenum 405 scavenge has a section of higher radius so that the already trapped fine particles would continue to rotate freely in the tangential direction and help negate the need of active scavenge flow bleed.
In operation, therefore, the compressed air that exits the diffuser 204 at diffuser outlet 216 will enter the deswirl assembly at inlet 230. Any fine particles in the compressed air, as it passes through the deswirl flow path 228, will tend to track along the arc 233 of outer annular wall 222. As the particles pass along the outer annular wall 222 along the arc 233, the fine particles will be extracted from the flow path 228 through the plurality of holes 406, and enter into the scavenge plenum 405. In this manner, the fine particles are efficiently prevented from entering the combustion section 124, which is positioned axially downstream from the second plurality of vanes 226 and deswirl assembly outlet 232. Any fine particle accumulation in the scavenge plenum 405 may be removed from time to time by an appropriate port along any wall of the scavenge plenum 405, for example the “smart” system as described above.
With reference now to the third fine particle separation means 500, as detailed in
The previously-described embodiments have been set forth in connection with a radial compressor that is located immediate upstream of the combustor section, and including a diffuser and a deswirl assembly. However, other locations in a turbine engine are also possible. More broadly, the fine particle separation means of the present disclosure (300, 400, 500) may be generally positioned anywhere in the air flow path where there is an abrupt change in flow from the radial direction to the axial direction. For example,
As a further illustration of the concept that the fine particle separation means may be located in any gas turbine engine compressor section (not just radial/centrifugal compressor sections) where there is an abrupt change from a substantially radial flow to a substantially axial flow,
Accordingly, the present disclosure has provided various embodiments of fine particle separation means for use in gas turbine engines, such as propulsion-type engines and APUs. The improved propulsion turbine engines and APUs exhibit improved particle separation efficiency, particularly with regard to fine sand particles. As noted above, these engines may implement the novel particle separation means in addition to or as an alternative to conventional inlet particle separators, and may be located at positions within the engine that are different as compared to conventional inlet particle separators, for example in a compressor section (radial, mixed-flow) anywhere there is an abrupt change in flow path from the radial direction to the axial direction.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
