Abstract:
An anti-ice formation device for a gas turbine engine is configured to be mounted within an inlet duct of the engine, and adjacent the gas turbine engine compressor inlet. The device is configured to selectively receive a flow of compressed air that is discharged from the compressor. Because the compressed air is relatively hot, the anti-ice formation device temperature increases to a temperature sufficient to prevent ice accumulation and formation in the engine inlet duct. The anti-ice formation device is also configured such that heat is not transferred to the compressor inlet housing. As a result, the anti-ice formation device does not cause impeller clearance variations, which would adversely affect engine performance.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to ant-ice systems and, more particularly, to an anti-ice formation device and system for gas turbine engines that maintains sufficient axial clearances. 
       BACKGROUND 
       [0002]    Gas turbine engines are used in myriad systems and environments. For example, gas turbine engines are used in various types of aircraft and watercraft, and in numerous industrial systems and environments. In each of these exemplary systems and environments, gas turbine engines may be used to supply propulsion power, to generate electrical power, or both. No matter its specific end-use, a gas turbine engine typically includes a combustor, a power turbine, and a compressor. During operation, the compressor draws in ambient air, compresses it, and supplies compressed air to the combustor. The combustor receives fuel from a fuel source and the compressed air from the compressor, and supplies high energy combustion gas to the power turbine, causing it to rotate. The power turbine includes a shaft that may be used to drive the compressor. Moreover, depending upon the particular end-use, the turbine may additionally drive a generator, a turbo fan, or a shaft that drives a power source. 
         [0003]    In addition to its potentially myriad uses, a gas turbine engine may also be exposed to numerous and varied environmental conditions. For example, a gas turbine engine may be exposed to relatively high altitudes, adverse weather conditions, or numerous other conditions that may result in operation below freezing temperatures. During operations below freezing, ice formation may occur at various locations on or within the gas turbine engine. The gas turbine engine inlet is particularly prone to ice formation during such freezing conditions. Not surprisingly, excessive ice formation and accumulation, or the ingestion of ice into the inlet, can adversely affect gas turbine engine performance and/or have various other deleterious effects on gas turbine engine components. 
         [0004]    In particular, it is generally known that the operating efficiency of a gas turbine is at least partially dependent upon the axial clearance or gap between rotor blade tips and the shroud. If the axial clearance between the rotor blade tips and the surrounding shroud is too large, additional flow may leak through the gap between the rotor blade tips and the surrounding shroud, decreasing the turbine&#39;s efficiency. Conversely, if the axial clearance is too small, the rotor blade tips may strike the surrounding shroud during certain turbine operating conditions. It is also generally known that axial clearances may change due, among other factors, to relative thermal growth between the rotating rotor and stationary shroud. During periods of such differential thermal growth, clearance between the moving blade tips and the stationary shroud may occur. Since components of turbines and other rotating machines are, in many instances, made of different materials with different thicknesses, such components exhibit different rates of thermal growth from a cold startup condition to steady state operating condition and during transient operating conditions. 
         [0005]    To facilitate optimizing turbine efficiency, various clearance management tools and/or design methodologies may be used to attain a balanced design that provides relatively tight operating clearances, yet avoids potential rubbing during transients and/or during operations at off-design conditions and/or that may result from differential thermal growth. Various anti-ice formation devices presently known do not provide adequate thermal isolation to differential thermal growth. 
         [0006]    Hence, there is a need for a device and system that prevents, or at least substantially prevents, ice formation and accumulation on a gas turbine engine inlet and/or ice ingestion into a gas turbine engine inlet, and that does not adversely impact axial clearances within the engine. The present invention addresses at least this need. 
       BRIEF SUMMARY 
       [0007]    In one embodiment, and by way of example only, an anti-ice formation device that is for a gas turbine engine that includes at least a compressor inlet, comprises a flow body, a mount structure, and a plurality of spaced-apart supports. The flow body is configured to surround at least a portion of the compressor inlet and includes an inner surface, an outer surface, and an inlet port. The inner surface defines a flow cavity, and the inlet port extends between the flow body inner and outer surfaces and is adapted to receive a flow of fluid. The mount structure is spaced apart from the flow body and is adapted to be disposed within, and coupled to, the compressor inlet. The mount structure includes at least one discharge flow passage. The plurality of spaced-apart supports are coupled to the flow body and the mount structure. At least one of the supports includes a flow passage that is in fluid communication with the flow body cavity and the at least one mount structure discharge flow passage. 
         [0008]    In another exemplary embodiment, an anti-ice system for gas turbine engine that includes at least a compressor having a compressor inlet, comprises an anti-ice control valve and an anti-ice formation device. The anti-ice control valve includes a valve inlet and a valve outlet. The valve inlet is adapted to receive a flow of compressed air discharged from a gas turbine engine compressor. The anti-ice control valve is movable between a closed position, in which the valve inlet is not in fluid communication with the valve outlet, and an open position, in which the valve inlet is in fluid communication with the valve outlet. The anti-ice formation is device coupled to the anti-ice control valve and is configured to mount adjacent the compressor inlet. The anti-ice formation device includes a flow body, a mount structure, and a plurality of spaced-apart supports. The flow body is configured to surround at least a portion of the compressor inlet and includes an inner surface, an outer surface, and an inlet port. The inner surface defines a flow cavity, and the inlet port extends between the flow body inner and outer surfaces and is in fluid communication with the valve outlet. The mount structure is spaced apart from the flow body and is adapted to be disposed within, and to be coupled to, the compressor inlet. The mount structure includes at least one discharge flow passage. The plurality of spaced-apart supports are coupled to the flow body and the mount structure. At least one the spaced-apart supports includes a flow passage that is in fluid communication with the flow body cavity and the at least one mount structure discharge flow passage. 
         [0009]    In yet another exemplary embodiment, a gas turbine engine includes a housing, a compressor, a combustor, a turbine, and an anti-ice formation device. The housing has an inlet duct. The compressor, combustor, and turbine are all mounted in flow series within the housing. The compressor has an inlet in fluid communication with the housing inlet duct. The anti-ice formation device is mounted within the housing inlet duct and adjacent the compressor inlet. The anti-ice formation device comprises a flow body, a mount structure, and a plurality of spaced-apart supports. The flow body is configured to surround at least a portion of the compressor inlet and includes an inner surface, an outer surface, and an inlet port. The inner surface defines a flow cavity. The inlet port is coupled to at least selectively receive a flow of compressed air discharged from the compressor. The mount structure is spaced apart from the flow body, is disposed within, and coupled to, the compressor inlet housing, and includes at least one discharge flow passage. The plurality of spaced-apart supports are coupled to the flow body and the mount structure. At least one of the spaced-apart supports includes a flow passage that is in fluid communication with the flow body cavity and the at least one mount structure discharge flow passage. 
         [0010]    Other desirable features and characteristics of the anti-ice formation device and system will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
           [0012]      FIG. 1  is a simplified schematic diagram of an exemplary gas turbine engine; 
           [0013]      FIG. 2  is a plan view of an exemplary anti-ice formation device that may be mounted within the gas turbine engine of  FIG. 1 ; 
           [0014]      FIG. 3  is a front view of the exemplary anti-ice formation device depicted in  FIG. 2 ; 
           [0015]      FIG. 4  is a cross section view of the exemplary anti-ice formation device taken along line  4 - 4  in  FIG. 3 ; 
           [0016]      FIG. 5  is a cross section view of a portion of the exemplary anti-ice formation device taken along line  5 - 5  in  FIG. 3 ; 
           [0017]      FIG. 6  is a partial cross section view of a portion of a physical implementation of the gas turbine engine of  FIG. 1  with the exemplary anti-ice formation device of  FIGS. 2-5  mounted therein. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0018]    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. 
         [0019]    Turning now to  FIG. 1 , an embodiment of an exemplary gas turbine engine  100  is shown in simplified schematic form. The gas turbine engine  100  includes a compressor  102 , a combustor  104 , and a turbine  106 , all preferably housed within an engine housing  108 . During operation of the gas turbine engine  100 , the compressor  102  draws ambient air into a compressor inlet  101 , via a housing inlet duct  103  formed in the engine housing  108 . The compressor  102  compresses the ambient air, and supplies a portion of the compressed air to the combustor  104 , and may also supply compressed air to a bleed air port  105 . The bleed air port  105 , if included, may be used to supply compressed air to, for example, a non-illustrated environmental control system or other load. It will be appreciated that the compressor  102  may be any one of numerous types of compressors now known or developed in the future. For example, the compressor may be a single-stage or a multi-stage centrifugal compressor. 
         [0020]    The combustor  104  receives the compressed air from the compressor  102 , and also receives a flow of fuel from a non-illustrated fuel source. The fuel and compressed air are mixed within the combustor  104 , and are ignited to produce relatively high-energy combustion gas. The combustor  104  may be implemented as any one of numerous types of combustors now known or developed in the future. Non-limiting examples of presently known combustors include various can-type combustors, various reverse-flow combustors, various through-flow combustors, and various slinger combustors. 
         [0021]    No matter the particular type of combustor  104  that is used, the relatively high-energy combustion gas that is generated in the combustor  104  is supplied to the turbine  106 . As the high-energy combustion gas expands through the turbine  106 , it impinges on the turbine blades (not shown in  FIG. 1 ), which causes the turbine  106  to rotate. It will be appreciated that the turbine  106  may be implemented using any one of numerous types of turbines now known or developed in the future including, for example, a vaned radial turbine, a vaneless radial turbine, and a vaned axial turbine. No matter the particular type of turbine that is used, the turbine  106  includes an output shaft  112  that drives the compressor  102 . Moreover, depending on the particular end-use of the gas turbine engine  100 , the turbine  106 , via the output shaft  112 , may also drive a non-illustrated generator, a non-illustrated propeller, and/or one or more numerous other non-illustrated components. 
         [0022]    The gas turbine engine  100  may be exposed to relatively high altitudes, adverse weather conditions, or various other conditions that may result in operation in environments below freezing temperatures. Thus, the gas turbine engine  100  also preferably includes an anti-ice formation system  120  to prevent excessive ice formation and accumulation on, and thus ice ingestion into, the compressor inlet  101  and the housing inlet duct  103 . The anti-ice formation system  120  includes an anti-ice control valve  122  and an anti-ice formation device  124 . The anti-ice control valve  122  includes a valve inlet  126  and a valve outlet  128 . The valve inlet  126  is coupled to receive a portion of the compressed air discharged from the compressor  102 , and the valve outlet  128  is coupled to the anti-ice formation device  124 . 
         [0023]    The anti-ice control valve  122  is movable between a closed position and an open position. In the depicted embodiment, the anti-ice control valve  122  responds to valve position command signals supplied thereto from a remote source. It will be appreciated that the remote source may be responsive to user input to supply the appropriate valve command signals, or may be responsive to one or more sensor inputs to automatically supply the appropriate valve commands. In either case, when the valve  122  is in the closed position, the valve inlet  126  is not in fluid communication with the valve outlet  128 , and thus compressed air is not supplied to the ant-ice formation device  124 . Conversely, when the valve  122  is in an open position, the valve inlet  126  is in fluid communication with the valve outlet  128 , and a portion of the compressed air discharged from the compressor  102  is supplied to the anti-ice formation device  124 . It will additionally be appreciated that the valve  122  is not included in some embodiments. 
         [0024]    The anti-ice formation device  124  is mounted within the housing inlet duct  103  and adjacent the compressor inlet  101  and, when the anti-ice control valve  122  is in the open position, receives a flow of compressed air that is discharged from the compressor  102 . As will be described in more detail below, the compressed air flows in and through the anti-ice formation device  124 , and is discharged into the engine housing  108 . As may be appreciated, the compressed air discharged from the compressor  102  is at a relatively high temperature, thus heating the anti-ice formation device  124  to a temperature that prevents ice formation and accumulation in the compressor inlet  101  and housing inlet duct  103 . A preferred embodiment of the anti-ice formation device  124  is depicted in  FIGS. 2-5 , and with reference thereto will now be described in more detail. 
         [0025]    The anti-ice formation device  124  includes a flow body  202 , a mount structure  204 , and a plurality of spaced-apart supports  206 . The flow body  202 , which is preferably substantially ring-shaped, is configured to surround at least a portion of the compressor inlet  101  and, as shown most clearly in  FIG. 4 , includes an inner surface  402  and an outer surface  404 . The inner surface defines a cavity  406 , through which compressed air may flow. As shown most clearly in  FIG. 5 , the flow body  202  additionally includes an inlet port  502  that extends between the flow body inner  402  and outer  404  surfaces. The inlet port  502 , when disposed within the gas turbine engine  100 , is coupled to at least selectively receive a flow of compressed air discharged from the compressor  102  via, for example, the anti-ice control valve  122 . 
         [0026]    In the depicted embodiment, the anti-ice formation device  124  also includes an inlet boss  208  that extends from the flow body outer surface  404 . The inlet boss  208  includes an inlet passage  504 , which is shown most clearly in  FIG. 5 , that is in fluid communication with the flow body inlet port  502 . Preferably, a non-illustrated conduit extends between the inlet boss  208  and the anti-ice control valve  122  (if included), and provides fluid communication between the anti-ice formation device  124  and the anti-ice control valve  122 . 
         [0027]    Returning again to  FIG. 2 , the mount structure  204 , which is also preferably substantially ring-shaped, is spaced apart from the flow body  202 , but is coupled to the flow body  202  via the spaced-apart supports  206 . Thus, a flow area  210  is defined between the flow body  202 , the mount structure  204 , and between each of the supports  206 . With quick reference once again to  FIG. 4 , it is seen that the mount structure  204  includes at least one discharge passage  408 , and that at least one of the supports  206  has a flow passage  412  formed therein that provides fluid communication between the flow body cavity  406  and the discharge flow port  408 . In the preferred embodiment, a flow passage  412  is formed in each of the supports  206 , and the mount structure  204  includes a discharge flow passage  408  associated with each of the flow passages  412 . No matter the particular number of discharge flow passages  408  and support flow passages  412 , it will be appreciated that when compressed air is supplied to the flow body cavity  406 , the compressed air will circulate around the cavity  406 , flow through the support flow passages  412 , and be discharged from the discharge flow passages  408 . 
         [0028]    As will be described in more detail further below, the mount structure  204  is preferably coupled to the compressor inlet  101  via a plurality of fasteners. Thus, in the depicted embodiment, the mount structure  204  includes a main body  212  and a mount flange  214 . The main body  212  is coupled to each of the plurality of supports  206 , and each of the discharge flow passages  408  is formed therein. As  FIG. 2  additionally shows, a seal groove  216  is preferably formed in an outer peripheral surface  218  of the main body  212 . A seal  414 , which is shown most clearly in  FIG. 4 , may be disposed within the seal groove  216  to seal the inlet plenum. The mount flange  214  extends radially inwardly from the main body  212 , and a plurality of fastener openings  222  extend axially through the mount flange  214 . The plurality of fasteners that are used to couple the mount structure  204  to the compressor inlet  101  extend, one each, through each of the fastener openings  222 . Moreover, and as will now be described, the anti-ice formation device  124  is configured such that when it is mounted within the gas turbine engine  100 , via the plurality of fasteners, there is a small radial air gap between the structure that defines the compressor inlet  101  and at least portions of the anti-ice formation device  124 . Before doing so, however, it is noted that although the depicted anti-ice formation device  124  is mounted via the mount structure  204 , it will be appreciated that the device  124  could alternatively be mounted via the flow body  202 . 
         [0029]    Turning now to  FIG. 6 , a partial cross section view of a portion of a physical implementation of the gas turbine engine  100  with the anti-ice formation device  124  mounted therein is depicted and will now be briefly described. The portion of the gas turbine engine  100  that is depicted in  FIG. 6  is a portion of the compressor  102 , and the compressor inlet  101 . The compressor inlet  101  is defined by an aft annular housing  602  and a forward annular housing  604  that are spaced apart from each other and interconnected by a plurality of axially disposed struts  606  to form an annular inlet flow path  608  to the compressor  102 . The compressor  102 , at least in the depicted embodiment, is a two-stage centrifugal compressor (only one stage depicted in  FIG. 6 ) that includes a centrifugal impeller  612  and a hub  614 . The impeller  612  is coupled to the hub  614 , which is in turn coupled to the above-mentioned output shaft  112 . 
         [0030]    The anti-ice formation device  124  is mounted within the housing inlet duct  103  and adjacent the compressor inlet  101 . More specifically, the anti-ice formation device flow body  202  surrounds at least a portion of the compressor inlet aft housing  604 , and the mount structure  204  is coupled to, and surrounds at least a portion of, the compressor inlet forward housing  604 . As previously mentioned, the anti-ice formation device  124  is coupled to the compressor inlet  101  via a plurality of fasteners  603  that extend, one each, through each of the compressor inlet struts  608  and each of the fastener openings  222  that are formed in the mount flange  214 . Moreover, each of the anti-ice formation device supports  206  (only one depicted in  FIG. 6 ) extends across, and is at least substantially axially aligned with, one of the compressor inlet struts  608 . 
         [0031]    As  FIG. 6  additionally depicts, in a somewhat exaggerated form for clarity, the anti-ice formation device  124  is preferably configured such that, when it is mounted within the housing inlet duct  103 , it is at least partially spaced-apart from the compressor inlet  101 . Thus, a small air gap  616  is preferably defined between the anti-ice formation device  124  and at least portions of the compressor inlet  101 . The air gap  616  provides thermal insulation between the anti-ice formation device  124  and the compressor inlet  101 . As a result, when relatively hot compressed air is supplied to the anti-ice formation device  124 , the compressor inlet  101  temperature is not substantially impacted. Minimizing compressor inlet  101  temperature variations minimizes any impact that such temperature variations may have on clearances between the compressor impeller  612  and the compressor shroud  622 . In turn, any impact such temperature variations may have on engine performance is minimized. It will be appreciated that the size of the air gap  616  may vary depending, for example, on the size and type of engine being used, but in one particular embodiment an air gap size of about 0.015-inch was sufficient. 
         [0032]    In addition to being configured with the air gap  616 , it will be appreciated that one or more seals may be disposed between the anti-ice formation device  124  and the compressor inlet  101 . In the depicted embodiment, it is seen that a seal  618  is disposed between the anti-ice formation device flow body  202  and the aft annular housing  602 . The seals  618 , if included, provides vibration damping between the anti-ice formation device  124  and the compressor inlet  101 . It will be appreciate that the configuration of the seals  618 ,  622  may vary, but are preferably configured as O-ring seals. 
         [0033]    With continued reference to  FIG. 6 , it may be seen that when compressed air, which is represented via the flow arrows, is supplied to flow body  202 , the compressed air flows around the cavity  406 , and into each of the flow passages  412  in the supports  206 . The compressed air then flows through the associated discharge flow passages  408  formed in the mount structure  204 , and is discharged into a cavity  624  in the engine housing  108 . Thus, the relatively hot compressed air is not ingested into the compressor  102 , or any other portion of the engine flow path. 
         [0034]    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.