Patent Publication Number: US-8978829-B2

Title: Turbomachine fluid delivery system

Description:
BACKGROUND 
     This disclosure relates generally to a fluid delivery system and, more particularly, to a fluid delivery system for controlling turbomachine fluid flow in positive and negative g-force flight environments. 
     Turbomachines, such as gas turbine engines, typically include a fan section, a compression section, a combustion section, and a turbine section. Turbomachines may employ a geared architecture connecting portions of the compression section to the fan section. 
     Turbomachines may be used to propel an aircraft in flight, for example. The g-force acting on the turbomachine is typically positive when the aircraft is in flight. Occasionally, the g-force acting on the turbomachine is negative when the aircraft is in flight. Some areas of the turbomachine require a relatively constant supply of lubricant. These areas must receive lubricant when positive g-forces act on the turbomachine and when negative g-forces act on the turbomachine. 
     SUMMARY 
     A system for delivering a turbomachine fluid to a supplied area according to an exemplary aspect of the present disclosure includes, among other things, a pump configured to draw fluid from both a first container and a second container when operating in both a positive g-force environment and a negative g-force environment. The fluid from the first container in a positive g-force environment is a mixture of air and oil, and the fluid from the first container in a negative g-force environment is primarily oil. 
     In a further non-limiting embodiment of the foregoing system, the fluid from the second container in a positive g-force environment may be a mixture of oil and air, and the fluid from the second container in a negative g-force environment may be primarily air. 
     In a further non-limiting embodiment of either of the foregoing systems, the fluid from the second container in a zero g-force in the environment may be primarily air, and the fluid from the second container in a negative g-force environment may be primarily air. 
     In a further non-limiting embodiment of any of the foregoing systems, the fluid from the first container when the turbomachine is not operating may be primarily air, and the fluid from the second container when the turbomachine is not operating may be primarily oil. 
     In a further non-limiting embodiment of any of the foregoing systems, the pump may be a two-stage pump. 
     In a further non-limiting embodiment of any of the foregoing systems, the pump is a gear pump. 
     In a further non-limiting embodiment of any of the foregoing systems, the pump may communicate a mixture of fluid from the first container and the second container to a geared architecture of a turbomachine. 
     In a further non-limiting embodiment of any of the foregoing systems, the pump may communicate fluid to a journal bearing of the geared architecture. 
     In a further non-limiting embodiment of any of the foregoing systems, the first container may be at an elevation higher than the second container. 
     In a further non-limiting embodiment of any of the foregoing systems, the first container may be an auxiliary lubricant tank, and the second container may be a sump associated with the auxiliary lubricant tank. 
     A turbomachine fluid delivery system according to an exemplary aspect of the present disclosure includes, among other things, a first turbomachine fluid container, a second turbomachine fluid container, a supplied area, and a pump configured to move a flow of a turbomachine fluid to the supplied area. The first and second turbomachine fluid containers together provide the flow to the pump in both a positive g-force environment and a negative g-force environment. 
     In a further non-limiting embodiment of the foregoing turbomachine fluid delivery system, the turbomachine fluid from the first turbomachine fluid container when operating in a positive g-force environment may be a mixture of air and oil, and the turbomachine fluid from the first turbomachine fluid container in a negative g-force environment may be primarily oil. 
     In a further non-limiting embodiment of either of the foregoing turbomachine fluid delivery systems, the pump may receive primarily oil from both the first turbomachine fluid container and the second turbomachine fluid container when operating in a positive g-force environment, primarily oil from the first container when operating in a negative g-force environment, and primarily oil from the second container when the turbomachine is not operating. 
     In a further non-limiting embodiment of any of the foregoing turbomachine fluid delivery systems, the supplied area may be a geared architecture of a turbomachine. 
     In a further non-limiting embodiment of any of the foregoing turbomachine fluid delivery systems, the supplied area may be a journal bearing of the geared architecture. 
     In a further non-limiting embodiment of any of the foregoing turbomachine fluid delivery systems, the first turbomachine fluid container may be an auxiliary lubricant tank, and the second turbomachine fluid container may be a sump associated with the auxiliary lubricant tank. 
     A method of controlling a turbomachine fluid flow according to another exemplary aspect of the present disclosure includes, among other things, communicating a turbomachine fluid to a supplied area when operating in both a positive g-force environment and a negative g-force environment. The communicated turbomachine fluid is a combination of fluid from both a first turbomachine fluid container and a second turbomachine fluid container 
     In a further non-limiting embodiment of the foregoing method of controlling a turbomachine fluid flow, the first and second turbomachine fluid containers may both provide primarily oil to a pump when operating in the positive g-force environment, and the first container may provide primarily oil to the pump when operating in the negative g-force environment. 
     In a further non-limiting embodiment of either of the foregoing methods of controlling a turbomachine fluid flow, the supplied area may be a geared architecture of a turbomachine. 
     In a further non-limiting embodiment of any of the foregoing methods of controlling a turbomachine fluid flow, the first container may be an auxiliary lubricant tank, and the second container may be a sump associated with the auxiliary lubricant tank. 
    
    
     
       DESCRIPTION OF THE FIGURES 
       The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows: 
         FIG. 1  shows a schematic view of an example turbomachine. 
         FIG. 2  shows a highly schematic view of an example turbomachine fluid delivery system in a positive g-force environment. 
         FIG. 3  shows a highly schematic view of the example turbomachine fluid delivery system in a negative g-force environment. 
         FIG. 4  shows a highly schematic view of the example turbomachine fluid delivery system in a zero g-force environment. 
         FIG. 5  shows a highly schematic view of the example turbomachine fluid delivery system in a windmilling environment. 
         FIG. 6  is a summary table showing how fluid is delivered in different flight environments. 
         FIG. 7  shows a partially schematic view of another example fluid delivery system in a positive g-force environment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates an example turbomachine, which is a gas turbine engine  20  in this example. The gas turbine engine  20  is a two-spool turbofan gas turbine engine that generally includes a fan section  22 , a compression section  24 , a combustion section  26 , and a turbine section  28 . 
     Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans. That is, the teachings may be applied to other types of turbomachines and turbine engines including three-spool architectures. Further, the concepts described herein could be used in environments other than a turbomachine environment and in applications other than aerospace applications, such as automotive applications. 
     In the example engine  20 , flow moves from the fan section  22  to a bypass flowpath. Flow from the bypass flowpath generates forward thrust. The compression section  24  drives air along the core flowpath. Compressed air from the compression section  24  communicates through the combustion section  26 . The products of combustion expand through the turbine section  28 . 
     The example engine  20  generally includes a low-speed spool  30  and a high-speed spool  32  mounted for rotation about an engine central axis A. The low-speed spool  30  and the high-speed spool  32  are rotatably supported by several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively, or additionally, be provided. 
     The low-speed spool  30  generally includes a shaft  40  that interconnects a fan  42 , a low-pressure compressor  44 , and a low-pressure turbine  46 . The shaft  40  is connected to the fan  42  through a geared architecture  48  to drive the fan  42  at a lower speed than the low-speed spool  30 . 
     The high-speed spool  32  includes a shaft  50  that interconnects a high-pressure compressor  52  and high-pressure turbine  54 . 
     The shaft  40  and the shaft  50  are concentric and rotate via bearing systems  38  about the engine central longitudinal axis A, which is collinear with the longitudinal axes of the shaft  40  and the shaft  50 . 
     The combustion section  26  includes a circumferentially distributed array of combustors  56  generally arranged axially between the high-pressure compressor  52  and the high-pressure turbine  54 . 
     In some non-limiting examples, the engine  20  is a high-bypass geared aircraft engine. In a further example, the engine  20  bypass ratio is greater than about six (6 to 1). 
     The geared architecture  48  of the example engine  20  includes an epicyclic gear train, such as a star/planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3 (2.3 to 1). 
     The low-pressure turbine  46  pressure ratio is pressure measured prior to inlet of low-pressure turbine  46  as related to the pressure at the outlet of the low-pressure turbine  46  prior to an exhaust nozzle of the engine  20 . In one non-limiting embodiment, the bypass ratio of the engine  20  is greater than about ten (10 to 1), the fan diameter is significantly larger than that of the low pressure compressor  44 , and the low-pressure turbine  46  has a pressure ratio that is greater than about 5 (5 to 1). The geared architecture  48  of this embodiment is an epicyclic gear train with a gear reduction ratio of greater than about 2.3 (2.3 to 1). It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans. 
     In this embodiment of the example engine  20 , a significant amount of thrust is provided by the bypass flow B due to the high bypass ratio. The fan section  22  of the engine  20  is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. This flight condition, with the engine  20  at its best fuel consumption, is also known as “Bucket Cruise” Thrust Specific Fuel Consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust. 
     Fan Pressure Ratio is the pressure ratio across a blade of the fan section  22  without the use of a Fan Exit Guide Vane system. The low Fan Pressure Ratio according to one non-limiting embodiment of the example engine  20  is less than 1.45 (1.45 to 1). 
     Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of Temperature divided by 518.7^0.5. The Temperature represents the ambient temperature in degrees Rankine. The Low Corrected Fan Tip Speed according to one non-limiting embodiment of the example engine  20  is less than about 1150 fps (351 m/s). 
     Referring to  FIG. 2  with continuing reference to  FIG. 1 , an example turbomachine fluid delivery system  60  includes a pump  62  that is used to deliver a turbomachine fluid  66 , for example, lubricant, to a supplied area  68 . The turbomachine fluid  66  from the pump  62  is a mixture of fluid moved along a conduit  70  from a first container  72 , and fluid moved along a conduit  74  from a second container  76 . The mixture of fluid is a mixture of lubricant, such as oil, and air in this example. 
     The first container  72 , in this example, is supplied with fluid from a gutter system associated with the geared architecture  48  of the engine  20 . Other than one or more inlets  78  to the first container  72  and one or more outlets  79  (to the conduit  70 ), the first container  72  is enclosed. The example outlets  79  are provided in a vertical top portion of the conduit  70 . 
     In this example, the operating engine  20  sprays fluid into the gutter and the first container  72 , which pressurizes the first container  72 , and keeps the first container  72  filled with a fluid  80 . The fluid  80  is typically a foamy mix of air and oil. The elevation of the first container  72  is higher than the elevation of the second container  76 . 
     The engine  20  typically operates in a positive g-force environment when an aircraft propelled by the engine  20  is in flight. In the positive g-force environment, positive g-forces act on the engine  20 . In positive g-force environments, the positive g-forces cause the fluid  80  filling the first container  72  to collect near a vertical bottom  82  of the first container  72 . The first container  72  is typically completely filled with the fluid  80 . The positive g-forces also cause a fluid  84  to collect at a vertical bottom  86  of the second container  76 . As used herein, elevation and vertical relationships refer to distance or height above a reference height when the engine  20  is on level ground or in straight and level flight. 
     Referring now to  FIG. 3 , the engine  20  occasionally may operate in a negative g-force environment when an aircraft propelled by the engine  20  is in flight. In the negative g-force environment, negative g-forces act on the engine  20 . In negative g-force environments, the negative g-forces cause the fluid  80  within the first container  72  to be forced upward toward a vertical top  88  of the first container  72 . The negative g-forces also cause the fluid  80  to be forced upward to a vertical top  90  of the second container  76 . Velocity of the incoming fluid  80  to inlets  78  in the negative g-force environment prevents the fluid  80  within first container  78  from backflowing out inlet  78 . 
     In this example, the supplied area  68  is the geared architecture  48  of the engine  20 , and specifically a journal bearing associated with the geared architecture  48 . The journal bearings require the turbomachine fluid  66  in both the positive g-force environment and the negative g-force environment. The supplied area  68  may be other areas of the engine  20  in other examples. 
     The example pump  62  is a two-stage, rotary pump, which may be considered a constant volume pump. The pump  62  many include two separate gear pumps driven by the same rotating shaft, which is powered by the rotating engine  20 . One of the gear pumps may move fluid from the first container  72  along the conduit  70 , and the other of the gear pumps may move fluid from the second container  76  along the conduit  74 . The example pump  62  pressurizes the fluid  80  and the fluid  84 . The fluids  80  and  84  are then mixed near the exit of pump  62 . The pump  62  may have other numbers of stages in other examples. 
     In this example, in the positive g-force environment ( FIG. 2 ), the fluid  80  drawn from the first container  72  is a mixture of oil and air. Also, in the positive g-force environment, the fluid  84  drawn from the second container  76  is a mixture of oil and air. The pump  62  compresses any air within the turbomachine fluid  66  so that the turbomachine fluid  66  delivered to the supplied area  68  is primarily oil. Again, the turbomachine fluid  66  delivered to the supplied area  68  is a mixture of the fluid  80  drawn from the first container  72  and the fluid  84  drawn from the second container  76 . 
     In this example, in the negative g-force environment, the fluid  80  drawn from the first container  72  is primarily oil. The negative g-forces cause most of the air within the first container  72  to separate from the oil within the first container  72 . Also, in the negative g-force environment, the fluid  84  drawn from the second container  76  is primarily air as the oil has moved vertically upwards past an inlet  92  pulling fluid  84  from the second container  76 . 
     The second container  76  is a sump having an open top which collects overflow from the first container  72 . The inlet  92  is provided within a dipper tube  94  of the conduit  74 . 
       FIG. 4  shows the turbomachine fluid delivery system  60  in a zero g-force environment, which is the transition between the positive and negative g-force environments. In the zero g-force environment, the fluid  80  from the first container  72  is a mixture of oil and air, and the fluid from the second container  76  is primarily air. In the zero g-force environment, the fluid may move out of the second container  76  through the open top, which causes the inlet  92  to draw the air, rather than oil or a mixture of air and oil from the second container  76 . 
       FIG. 5  shows the turbomachine fluid delivery system  60  in an environment when the engine  20  is windmilling in the air during flight. The g-force is positive in this example, when the engine  20  is windmilling. The pump  62  is driven from the fan  42  when the engine  20  is windmilling. When the engine  20  is windmilling in the positive g-force environment, the fluid  80  from the first container  72  is primarily air as the engine  20  is not rotating fast enough to support filling the first container  72 . The fluid  84  from the second container  76  is primarily oil. A negative g-force environment is typically ten seconds or less in duration. When the engine  20  is windmilling in a negative g-force environment, the loads on bearings and other lubricated structures are typically low enough that an oil interruption for ten seconds will not cause a failure. 
     Referring to  FIG. 6  with continuing reference to  FIGS. 2-5 , a table  100  summarizes the fluid provided from the first container  72  and the second container  76  at the various flight environments discussed above. 
       FIG. 7  shows a more detailed schematic view of another example turbomachine fluid delivery system  60   a  suitable for use in the engine  20  ( FIG. 1 ). As shown, a first container  72   a  may be an arcuate container arranged about the fan drive gear system of the geared architecture  48 . A second container  76   a  is vertically below the first container  72   a . The second container  72   a  is a sump that collects overflow from a gutter feed of the fan drive gear system. The overflow is fluid that does not enter the first container  72   a.    
     An engine pump  104  supplies lubricant to a journal oil shuttle valve  108  along a path  110 . The engine pump  104  draws the lubricant from a main engine tank  112 . The lubricant from the path  110  then moves to the geared architecture  48  along a path  114 . 
     A two-stage pump  62   a  also supplies a lubricant to the journal oil shuttle valve  108  along a path  116 . The lubricant move along the path  116  is lubricant from the first container  72   a  and the second container  76   a.    
     The journal oil shuttle valve  108  delivers the lubricant from the path  116  to the main engine tank  112  along the path  120  when the engine  20  is operating in the positive g-force environment. That is, when the engine  20  is operating in the positive g-force environment, the lubricant from the pump  62   a  is recirculated to the main engine tank  112 . 
     When the engine  20  is operating in a zero g-force environment, a negative g-force environment, or a windmilling environment, the journal oil shuttle valve  108  delivers lubricant from the path  116  directly to the geared architecture  48  along the path  114 . That is, when the engine  20  is not operating in a positive g-force environment, the journal oil shuttle valve  108  bypasses the main engine tank  112  and delivers lubricant from the path  116  directly to the geared architecture  48 . 
     A feature of the disclosed examples is a system having substantially no latent failure modes due to valves controlling flow within the containers. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.