Abstract:
A gas turbine engine assembly according to an exemplary aspect of the present disclosure includes, among other things, a geared architecture configured to rotatably couple a turbine and a compressor of an engine to rotate the compressor at a different speed than the turbine and a fan.

Description:
BACKGROUND 
       [0001]    A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-temperature exhaust gas flow. The high-temperature exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes at least low and high pressure compressors, and the turbine section typically includes at least low and high pressure turbines. 
         [0002]    The high pressure turbine drives the high pressure compressor through an outer shaft to form a high spool, and the low pressure turbine drives the low pressure compressor through an inner shaft to form a low spool. The fan section may also be driven by the low inner shaft. A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different and typically slower than the turbine section so as to provide a reduced part count approach for increasing the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds. 
         [0003]    Although geared architectures utilized to drive the fan have improved propulsive efficiency, turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer, and propulsive efficiencies. 
       SUMMARY 
       [0004]    A gas turbine engine assembly according to an exemplary aspect of the present disclosure includes, among other things, a geared architecture configured to rotatably couple a turbine and a compressor of an engine to rotate the compressor at a different speed than the turbine and a fan. 
         [0005]    In a further non-limiting embodiment of the foregoing gas turbine engine, the geared architecture is a first geared architecture, and the engine further includes a second geared architecture configured to rotatably couple to the fan to rotate the fan at a different speed than a spool that drives the fan. 
         [0006]    In a further non-limiting embodiment of either of the foregoing gas turbine engines, the geared architecture is axially upstream from the compressor relative to a direction of flow through the engine. 
         [0007]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the geared architecture the engine has a three spool architecture, and the turbine is an intermediate turbine. 
         [0008]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the geared architecture of the turbine is a high pressure turbine. 
         [0009]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the high pressure turbine is rotatably coupled to a high pressure compressor. 
         [0010]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the engine has a three spool architecture. 
         [0011]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the turbine is a low pressure turbine. 
         [0012]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the low pressure turbine is rotatably coupled to the fan. 
         [0013]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the compressor is an intermediate compressor. 
         [0014]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the geared architecture is configured to rotate the compressor at a faster rotational speed than the turbine. 
         [0015]    A gas turbine engine assembly according to another exemplary aspect of the present disclosure includes, among other things, a fan section; a turbine section; a compressor section; and a geared architecture rotatably coupling the compressor section and the turbine section to drive the compressor section at a different rotational speed than the turbine section and the fan section. 
         [0016]    In a further non-limiting embodiment of the foregoing gas turbine engine, the geared architecture is a first geared architecture, and the engine further includes a second geared architecture configured to rotatably couple to the fan section to rotate the fan section at a different speed than a spool driving the fan section. 
         [0017]    In a further non-limiting embodiment of either of the foregoing gas turbine engines, the engine has a three spool architecture, and the turbine section is an intermediate turbine. 
         [0018]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the turbine section is a high pressure turbine section configured to rotatably drive a high pressure compressor section. 
         [0019]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the turbine section is a low pressure turbine section configured to rotatably drive the fan section. 
         [0020]    In a further non-limiting embodiment of any of the foregoing gas turbine engines, the geared architecture is configured to rotate the compressor section at a faster rotational speed than the turbine section. 
         [0021]    A method of adjusting rotational speeds within a gas turbine engine includes among other things, providing a geared architecture that rotatably couples a turbine and a compressor of an engine to rotate the compressor at a different rotational speed than the turbine and a fan. 
         [0022]    In a further non-limiting embodiment of the foregoing method of adjusting rotational speeds, the geared architecture is a first geared architecture, and the method may include providing a second geared architecture that rotatably couples another turbine and the fan to rotate the fan at a different speed than the other turbine. 
         [0023]    In a further non-limiting embodiment of either of the foregoing methods of adjusting rotational speeds, the engine has a three spool architecture, and the turbine is an intermediate turbine. 
         [0024]    Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0025]    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: 
           [0026]      FIG. 1  shows a section view of an example gas turbine engine. 
           [0027]      FIG. 2  shows a section view of another example gas turbine engine. 
           [0028]      FIG. 3  shows a section view of yet another example gas turbine engine. 
           [0029]      FIG. 4  shows a section view of yet another example gas turbine engine. 
           [0030]      FIG. 5  shows a section view of yet another example gas turbine engine. 
           [0031]      FIG. 6  shows a section view of yet another example gas turbine engine. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]      FIG. 1  schematically illustrates an example gas turbine engine  20  that includes a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B while the compressor section  24  draws air in along a core flow path C where air is compressed and communicated to a combustor section  26 . In the combustor section  26 , air is mixed with fuel and ignited to generate a high temperature exhaust gas stream that expands through the turbine section  28  where energy is extracted and utilized to drive the fan section  22  and the compressor section  24 . 
         [0033]    Although the disclosed non-limiting embodiment depicts a gas turbine gas turbine engine, it should be understood that the concepts described herein are not limited to use with gas turbines as the teachings may be applied to other types of turbine engines; for example a turbine engine including a three-spool architecture in which three spools concentrically rotate about a common axis and where a low spool enables a low pressure turbine to drive a fan via a gearbox, an intermediate spool that enables an intermediate pressure turbine to drive a first compressor of the compressor section, and a high spool that enables a high pressure turbine to drive a second higher pressure compressor of the compressor section. 
         [0034]    The example engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing systems  38 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided. 
         [0035]    The low speed spool  30  generally includes an inner shaft  40  that connects a fan  42  and a low pressure (or first or most forward) compressor section  44  to a low pressure (or second or most rearward) turbine section  46 . The inner shaft  40  drives the fan  42  through a speed change device, such as 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 an outer shaft  50  that interconnects a high pressure (or second or most rearward) compressor section  52  and a high pressure (or first or most forward) turbine section  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate via the bearing systems  38  about the engine central longitudinal axis A. 
         [0036]    A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . In one example, the high pressure turbine  54  includes at least two stages to provide a dual-stage high pressure turbine  54 . In another example, the high pressure turbine  54  includes only a single stage. As used herein, a “high pressure” compressor or turbine experiences a higher pressure than a corresponding “low pressure” compressor or turbine. 
         [0037]    The example low pressure turbine  46  has a pressure ratio that is greater than about 5. The pressure ratio of the example low pressure turbine  46  is measured prior to an inlet of the low pressure turbine  46  as related to the pressure measured at the outlet of the low pressure turbine  46  prior to an exhaust nozzle. 
         [0038]    A mid-turbine frame  58  of the engine static structure  36  is arranged generally between the high pressure turbine  54  and the low pressure turbine  46 . The mid-turbine frame  58  further supports bearing systems  38  in the turbine section  28  as well as setting airflow entering the low pressure turbine  46 . 
         [0039]    The core airflow C is compressed by the low pressure compressor  44  then by the high pressure compressor  52  mixed with fuel and ignited in the combustor  56  to produce high temperature exhaust gases that are then expanded through the high pressure turbine  54  and low pressure turbine  46 . The mid-turbine frame  58  includes vanes  60 , which are in the core airflow path and may function as an inlet guide vane for the low pressure turbine  46 . Utilizing the vane  60  of the mid-turbine frame  58  as the inlet guide vane for low pressure turbine  46  results in a more axially compact structure and decreases the length of the low pressure turbine  46 . For a given rotational speed design limit on the fan  42 , the gear  48  enables the low pressure turbine  46  and low pressure compressor  44  to operate at higher speeds reducing the number of stages and corresponding airfoils. Thus, the compactness of the gas turbine engine  20  is increased and a lighter, reduced part count design may be achieved. 
         [0040]    The disclosed gas turbine engine  20  in one example is a high-bypass geared aircraft engine. In a further example, the gas turbine engine  20  includes a bypass ratio greater than about six (6), with an example embodiment being greater than about ten (10). The example geared architecture  48  is an epicyclical gear train, such as a planetary gear system, star gear system or other known gear system, with a gear reduction ratio of greater than about 2.3. 
         [0041]    In one disclosed embodiment, the gas turbine engine  20  includes a bypass ratio greater than about ten (10:1) and the fan diameter is significantly larger than an outer diameter of the low pressure compressor  44 . It should be understood, however, that the above parameters are only exemplary of one embodiment of a gas turbine engine including a geared architecture and that the present disclosure is applicable to other gas turbine engines. 
         [0042]    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. The flight condition of 0.8 Mach and 35,000 ft., with the engine at its best fuel consumption—also known as bucket cruise Thrust Specific Fuel Consumption (TSFC)—is the industry standard parameter of pound-mass (lbm) of fuel per hour being burned divided by pound-force (lbf) of thrust the engine produces at that minimum point. 
         [0043]    “Low fan pressure ratio” is the pressure ratio across the fan blade alone, without a Fan Exit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about 1.50. In another non-limiting embodiment the low fan pressure ratio is less than about 1.45. 
         [0044]    “Low corrected fan tip speed” is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram ° R)/(518.7° R)]̂0.5. The “Low corrected fan tip speed”, as disclosed herein according to one non-limiting embodiment, is less than about 1150 ft/second. 
         [0045]    The example gas turbine engine includes the fan  42  that comprises in one non-limiting embodiment less than about 26 fan blades. In another non-limiting embodiment, the fan section  22  includes less than about 20 fan blades. Moreover, in one disclosed embodiment the low pressure turbine  46  includes no more than about 6 turbine rotors schematically indicated at  34 . In another non-limiting example embodiment, the low pressure turbine  46  includes about 3 turbine rotors. A ratio between the number of fan blades and the number of low pressure turbine rotors is between about 3.3 and about 8.6. The example low pressure turbine  46  provides the driving power to rotate the fan section  22  and therefore the relationship between the number of turbine rotors  34  in the low pressure turbine  46  and the number of blades in the fan section  22  disclose an example gas turbine engine  20  with increased power transfer efficiency. 
         [0046]    Referring to  FIG. 2 , in another example engine  20   a  the geared architecture  48  is a first geared architecture, and the engine  20   a  further includes a second geared architecture  68 . The second geared architecture  68  rotatably couples the high pressure turbine  54  to the low pressure compressor  44 . The high pressure turbine  54  directly drives the high pressure compressor  52 . The high pressure turbine  54  drives the low pressure compressor  44  through the second geared architecture  68 . The second geared architecture  68  allows the low pressure compressor  44  to rotate at a different speed than the high pressure turbine  54 , the high pressure compressor  52 , or other portions of the high speed spool  32   a.    
         [0047]    In this example, the second geared architecture  68  is axially upstream from the low pressure compressor  44  relative to a direction of flow through the engine  20   a  and the free stream flow. This positioning may be used to reduce exposure of the second geared architecture  68  to the relatively high levels of thermal energy areas of the engine  20   a  closer to the turbine section  28 . 
         [0048]    Referring now to  FIG. 3 , in yet another example engine  20   b , the geared architecture  48  is a first geared architecture, and the engine  20   b  includes a second geared architecture  72  that rotatably couples the low pressure turbine  46  to the low pressure compressor  44 . The second geared architecture  72  allows the low pressure compressor  44  to rotate at a different speed than the low pressure turbine  46 , and other portions of the low speed spool  30   b.    
         [0049]    Rotating the low pressure compressor  44  at a relatively slower speed may be useful if, for example, because of packaging requirements, the low pressure compressor  44  is placed radially relatively far from the axis A. In such a configuration, rotating the low pressure compressor  44  at a slower speed that the low pressure turbine  46  can facilitate reducing instabilities, especially near the radially outer areas of the low pressure compressor  44 . In such a configuration, rotating the low pressure compressor  44  at a slower speed that the low pressure turbine  46  can also facilitate an increased design space for structural, aerodynamic performance or operability trades to be performed. 
         [0050]    The second geared architecture  72  is driven by the low speed spool  30   b , which also drives the first geared architecture  48  to rotate the fan  42  at a different speed than the low speed spool  30   b  through the selection of differing gear ratios in components  48  and  72 . In another example, the low pressure turbine  46  directly drives the fan  42  and the first geared architecture  48  is omitted from the engine  20   b . In such examples, the second geared architecture  72  may be used to rotate the low pressure compressor  44  at either a faster or slower speed the low pressure turbine  46  to facilitate compression. 
         [0051]    Referring now to  FIG. 4 , yet another example engine  20   c  has a three-spool configuration. In this example, the low pressure turbine  46  drives the geared architecture  48 , which is a first geared architecture, to rotate the fan  42  at a different speed than other portions of the low speed spool  30   c . The low pressure turbine  46 , in this example, does not drive the low pressure compressor  44 . In addition, the high pressure turbine  54  directly drives the high pressure compressor  52  through the high speed spool  32 . 
         [0052]    The example engine  20   c  also includes an intermediate pressure turbine  80  that is coupled to the low pressure compressor  44  via a second geared architecture  84  and an intermediate spool  31 . The second geared architecture  84  allows the intermediate pressure turbine  80  to rotatably drive the low pressure compressor  44  at a different speed than the intermediate pressure turbine  80 . The low pressure compressor  44  may be considered an intermediate compressor as it is rotatably driven by the intermediate pressure turbine  80 . The second geared architecture  84 , in some examples, is used to increase the rotational speed of the low pressure compressor  44  relative to the intermediate pressure turbine  80 , or to slow down the rotational speed of the low compressor  44  relative to the intermediate pressure turbine  80 . 
         [0053]    Referring now to  FIG. 5 , yet another example engine  20   d  has a three-spool configuration and the geared architecture  48  is a first geared architecture. In this example, a second geared architecture  98  rotatably couples the high pressure turbine  54  to an intermediate or “boost” compressor  96 . The boost compressor  96  provides compression between the low pressure compressor  44  and the high pressure compressor  52 . The compressor  96  is an intermediate or boost compressor due to its location and operation between the low pressure compressor  44  and the high pressure compressor  52 . 
         [0054]    In the example engine  20   d , the high pressure turbine  54  directly drives the high pressure compressor  52  and the boost compressor  96  via the high spool  32   d . The second geared architecture  98  enables the high pressure turbine  54  to directly drive the high pressure compressor  52  and to drive the boost compressor  96  at a different rotational speed. 
         [0055]    The example engine  20   d  also includes the intermediate pressure turbine  80  that directly drives the low pressure compressor  44   
         [0056]    Referring to  FIG. 6 , yet another example engine  20   e  has a three-spool configuration and the geared architecture  48  is a first geared architecture. In this example, a second geared architecture  100  rotatably couples the intermediate pressure turbine  80  to the intermediate or “boost” compressor  96 . 
         [0057]    In the example engine  20   e , the intermediate pressure turbine  80  directly drives the low pressure compressor  44  and the boost compressor  96  via an intermediate spool  31   e . The second geared architecture  100  enables the intermediate pressure turbine  80  to directly drive the low pressure compressor  44  and to drive the boost compressor  96  at a different rotational speed. 
         [0058]    The example engine  20   e  also includes the intermediate pressure turbine  80  that directly drives the low pressure compressor  44   
         [0059]    In any of the above example engines  20 - 20   e , the first geared architecture  48  and the second geared architectures,  68 ,  72 ,  84 ,  98 ,  100  can be used to change the relative directions of rotation (e.g., counterclockwise to clockwise) in addition to changing relative rotational speeds. 
         [0060]    In any of the above example engines  20 - 20   e , the first geared architecture  48  may be omitted from the engine  20 - 20   e  and the high pressure turbine  46  may directly drive the fan  42 . 
         [0061]    Features of the disclosed examples include utilizing a geared architecture to step up or step down a rotational input speed from a turbine section. Various advantages, including reduced stage count, reduced airfoil count, compressor stage loading optimization, establishment of rotor speed in recognition of local temperatures for rotor structural stress optimization, and the establishment of flowpath radial elevation desirable to accommodate adjacent components, may be possible by varying the speeds in this way. 
         [0062]    The example engines utilize geared architectures to adjust speeds. The geared architecture may include a planetary gear arrangement or a clutch in some examples. 
         [0063]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure. 
         [0064]    Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.