The present invention generally relates to turbofan jet engines, and more particularly relates to performance recovery systems and methods for turbofan jet engines.
Aircraft propulsion engines can be susceptible to foreign object ingestion events. Such events include, for example, ingestion of one or more birds by the engine intake section. The intake section includes an intake fan having a plurality of blades. Following an ingestion event, the fan blades have the potential to be deformed or damaged. Deformed or damaged fan blades may result in relatively large flow separation on the fan case. This can cause flow blockage and reduced engine performance, including undesirable engine thrust reduction.
To mitigate the likelihood of post-ingestion thrust reductions in aircraft propulsion engines, some government regulatory agencies mandate that certain aircraft propulsion engines be able to produce a minimum level of thrust after certain foreign object ingestion events, such as ingesting multiple birds. This mandated robustness is currently achieved passively by making certain fan components relatively stiffer than what may be necessary, thereby undesirably increasing engine weight, and thus overall operating costs.
Hence, there is a need for a system and method that mitigates the potential deleterious effects of a foreign object ingestion event. The present invention addresses at least this need.
In one embodiment, a turbofan engine intake assembly includes a fan case, an intake fan, a slot, and an annulus. The fan case is adapted to be mounted in an engine nacelle assembly, and includes an inner surface and an outer surface. The intake fan is mounted within the fan case and includes a plurality of radially extending fan blades. The slot extends through the fan case between the inner and outer surfaces, and at least partially extends around the fan case proximate the fan blades. The annulus is coupled to the outer surface and includes an inner surface that defines an annular plenum that is in fluid communication with the slot and atmosphere outside the fan case.
In another embodiment, a turbofan engine system includes a nacelle assembly, an intake section, a compressor section, a combustion section, and a gas turbine section mounted in the nacelle assembly. The intake section includes a fan case, an intake fan, a slot, and an annulus. The fan case is mounted in the engine nacelle, and includes an inner surface and an outer surface. The intake fan is mounted within the fan case and includes a plurality of radially extending fan blades. The slot extends through the fan case between the inner and outer surfaces, and at least partially extends around the fan case proximate the fan blades. The annulus is coupled to the outer surface and includes an inner surface that defines an annular plenum that is in fluid communication with the slot and atmosphere outside the fan case.
In yet another embodiment, a method of recovering engine performance in a turbofan gas turbine engine following foreign object ingestion is provided. The turbofan gas turbine engine includes an intake fan and a fan case. The intake fan is disposed within and is surrounded by the fan case and includes a plurality of fan blades. The method includes detecting when a foreign object has been ingested by the turbofan gas turbine engine. Upon detecting that a foreign object has been ingested, air is bled from a region proximate the blades of the intake fan through a slot in the fan case.
Furthermore, other desirable features and characteristics of the turbofan engine system performance recovery system and method will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
The present invention 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. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
Turning now to
The compressor section 104 may include one or more compressors 124, which raise the pressure of the air directed into it from the intake fan 114, and direct the compressed air into the combustion section 106. In the depicted embodiment, only a single compressor 124 is shown, though it will be appreciated that one or more additional compressors could be used. In the combustion section 106, which includes a combustor assembly 126, the compressed air is mixed with fuel supplied from a non-illustrated fuel source. The fuel and air mixture is combusted, and the high energy combusted fuel/air mixture is then directed into the turbine section 108.
The turbine section 108 includes one or more turbines. In the depicted embodiment, the turbine section 108 includes two turbines, a high pressure turbine 128, and a low pressure turbine 132. However, it will be appreciated that the engine 100 could be configured with more or less than this number of turbines. No matter the particular number, the combusted fuel/air mixture from the combustion section 106 expands through each turbine 128, 132, causing it to rotate. As the turbines 128 and 132 rotate, each drives equipment in the engine 100 via concentrically disposed shafts or spools. Specifically, the high pressure turbine 128 drives the compressor 124 via a high pressure spool 134, and the low pressure turbine 132 drives the intake fan 114 via a low pressure spool 136. The gas exhausted from the turbine section 108 is then directed into the exhaust section 112.
The exhaust section 112 includes a mixer 138 and an exhaust nozzle 142. The mixer 138 includes a centerbody 144 and a mixer nozzle 146, and is configured to mix the bypass air flow with the exhaust gas from the turbine section 108. The bypass air/exhaust gas mixture is then expanded through the propulsion nozzle 142, providing forward thrust.
Though not visible in
In addition to the intake fan 114, the depicted intake section 102 includes a fan case 202, a slot 204, and an annulus 206. The fan case 202, at least in the depicted embodiment, is mounted in the nacelle assembly 116 (not illustrated in
The intake fan 114 is mounted within the fan case 202 and includes a plurality of radially extending fan blades 218. It will be appreciated, however, that for clarity only a single fan blade 218 is depicted in
The slot 204 is formed in, and extends through, the fan case 202 between the inner and outer surfaces 208 and 212. The slot 204 preferably extends circumferentially around the fan case 202 and thus circumferentially surrounds the fan blades 218. It will be appreciated, however, that the slot 204 could extend only partially around the fan case 202. Moreover, the slot 204 need not extend continuously around the fan case 202, but may be interrupted by various support structure, such as, for example, struts. The slot 204 is preferably disposed at least proximate the fan blades 218. In a particular preferred embodiment, the slot 204 is disposed between the leading edge 222 and trailing edge 224 of each fan blade 218. The specific location between the leading edges 222 and trailing edges 224 may vary depending, for example, on engine type. For example, in some embodiments the slot 204 may be located midway between the leading edges 222 and trailing edges 224, whereas in other embodiments the slot 204 may be disposed closer to either the leading edges 222 or trailing edges 224. It will be appreciated that the slot 204 may also be disposed slight upstream of the leading edges 224 or slight downstream of the trailing edges. The width of the slot 204 may also vary to meet desired performance.
No matter the specific location and width of the slot 204, the annulus 206 is coupled to the outer surface 212 of the fan case 202 at the location of the slot 204. The annulus 206 may be variously shaped and configured, but includes at least an inner surface 226 that defines an annular plenum 228. The annulus 206 is also configured such that the annular plenum 228 is in fluid communication with the slot 204, and at least selectively in fluid communication with the atmosphere 232 outside of the fan case 202. It will be appreciated that the annular plenum 228 may be selectively placed in fluid communication with the atmosphere 232 using any one of numerous techniques. In the depicted embodiment, however, a conduit 234 and a valve 236 are used.
The conduit 234 includes an inlet port 238 and an outlet port 242. The inlet port 238 is in fluid communication with the annular plenum 228, and the outlet port 242 in fluid communication with the atmosphere 232. The valve 236 is mounted on the conduit 234 between the inlet port 238 and the outlet port 242, and is movable to a plurality of valve positions. The valve positions include a closed position and a plurality of open positions. In the closed position the valve 236 fluidly isolates the conduit inlet port 238 and outlet port 242, and thereby prevents (or at least substantially prevents) air from flowing through the slot 204, into the annular plenum 228, and out the conduit 234 to the atmosphere 228. In any one of the open positions the conduit inlet port 238 and outlet port 242 are in fluid communication, which allows air to flow through the slot 204, into the annular plenum 228, and out the conduit 234 to the atmosphere 228.
The valve 236 is preferably moved to a valve position via a valve actuator 244, which is coupled to the valve 236 and which may be implemented using any one of numerous types of pneumatic, hydraulic, or electric type of actuators. No matter how it is specifically implemented, the valve actuator 244 is coupled to receive valve actuator commands and is configured, upon receipt of the valve actuator commands, to selectively move the valve 236 to one of the plurality of valve positions. The valve actuator commands that are supplied to the valve actuator 244 may originate from a manually actuated switch or knob 246, such as the one depicted in phantom in
Before proceeding further, it is noted that a plurality of conduits 234 could extend between the annular plenum 228 and atmosphere 232, each having an associated valve 236. In
The engine control 248, which may be implemented as a full-authority digital engine control (FADEC), an electronic engine control (EEC), or any one of numerous other engine control configurations, receives data from various sensors 252. The sensors 252 sense various parameters such as, for example, engine throttle position, fuel flow, and various parameters within with the turbofan gas turbine engine 100. The engine control 248, based at least in part on these parameters, controls the operation of the turbofan gas turbine engine 100.
In addition to the above, the depicted engine control 248 is configured to detect a foreign object ingestion event, such as a bird ingestion event. The engine control 248 is further configured, upon detecting a foreign object ingestion event, to supply valve actuator commands to the valve actuator 244 that will cause the valve 236 to move from the closed position to an open position. The manner in which the engine control 248 detects a foreign object ingestion event may vary. For example, in some embodiments the engine control 248, based on data from at least selected ones of the sensors 252, detects a performance degradation of the turbofan gas turbine engine 100. In other embodiments the engine control 248, based on data from at least selected ones of the sensors 252, detects a change in the air pressure around the intake fan 114. No matter the specific foreign object ingestion event detection scheme that is used, when the valve 236 is subsequently moved to an open position, air flows through the slot 204, into the annular plenum 228, and out the conduit 234 to the atmosphere 228.
It has been found that bleeding air through the slot 204, into the annular plenum 228, and out the conduit 234 to the atmosphere 228 following a foreign object ingestion event reduces the size of flow separations that may be induced by the potential damage the ingested object may have caused. As a result, engine performance is improved relative to conventional turbofan gas turbine engines, which do not include provisions for this flow path. Indeed, models of pre-ingestion event and post-ingestion event operations in a conventional turbofan gas turbine engine and in a turbofan gas turbine engine that embodies the instant invention show that post-ingestion event total pressure ratio and total temperature ratio in an inventive turbofan gas turbine engine are higher than those of conventional engine.
The system and method described herein mitigate the potential deleterious effects of a foreign object ingestion event. As a result, lighter intake fan components may be used to construct aircraft propulsion engines and/or additional margin may be provided for certain foreign object ingestion events, such as multiple bird ingestion events.
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.