Patent Publication Number: US-11655726-B2

Title: Pressure and temperature sensors and related methods

Description:
BACKGROUND 
     The present disclosure relates to pressure and temperature sensing, and more particularly to pressure and temperature sensing in icing conditions. 
     Gas turbine engines, such as on aircraft, commonly employ sensors to measure parameters that influence engine performance. For example, temperature sensors are employed to measure temperature of air entering the compressor section of the gas turbine engine. Pressure sensors are employed to measure pressure of air entering the compressor section of the gas turbine engine. Such sensors are generally positioned in the airstream traversing the engine and are exposed to the external environment. 
     In some operating environments, such as during flight in icing conditions, temperature and pressure sensors can be exposed to ice and/or super-cooled moisture entrained within the airstream traversing the engine. The ice and/or super-cooled moisture can interrupt operation of some sensors, such as when ice is ingested by the sensor and/or when ice accretes on the sensor structure. And while heating can be employed to counter to ice crystal ingestion and/or ice accretion, heating can introduce error into temperature measurements provided by the sensor. 
     Such systems and methods have generally been acceptable for their intended purpose. However, there remains a need for improved sensors, gas turbine engines, methods of making sensors, and methods to thermally separating temperature probes from heater elements in pressure and temperature sensors. 
     BRIEF DESCRIPTION 
     A sensor is provided. The sensor includes an airfoil body, a heater element, and a temperature probe. The airfoil body defines a sensor axis and an insulating cavity and extends between a leading edge and a trailing edge of the airfoil body. The heater element extends axially within the airfoil body and is positioned between the leading edge and the trailing edge of the airfoil body. The temperature probe extends axially within the airfoil body, is positioned between the heater element and the trailing edge of the airfoil body, and is separated from the heater element by the insulating cavity to limit thermal communication between the temperature probe and the heater element. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a tip surface extending to the trailing edge of the airfoil body. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the tip surface of the airfoil body defines an insulating cavity inlet that is fluidly coupled to the insulating cavity. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a first face extending between the leading edge and the trailing edge of the airfoil body, the first face defining a first face first outlet vent, and that the first face first outlet vent is fluidly coupled to the insulating cavity. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a second face extending between the leading edge and the trailing edge of the airfoil body, the second face defining a second face first outlet vent, and that the second face first outlet vent is fluidly coupled to the insulating cavity. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has an ice accretion feature extending between the tip surface and the leading edge of the air foil body, the ice accretion feature axially overlapping the leading edge of the airfoil body. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body defines a temperature sense chamber between the insulating cavity and the trailing edge of the airfoil body, and that the temperature probe extends into the temperature sense chamber. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a tip surface extending to the trailing edge of the airfoil body, the tip surface defining tip surface aperture, and that the tip surface aperture is fluidly coupled to the temperature sense chamber. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a first face extending between the leading edge and the trailing edge of the airfoil body, the first face defining a first face aperture, and that the temperature sense chamber is fluidly coupled to the external environment through the first face aperture. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a second face extending between the leading edge and the trailing edge of the airfoil body, the second face defining a second face aperture, and that the temperature sense chamber is fluidly coupled to the external environment through the second face aperture. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a tip surface defining therein a scoop feature, the scoop feature axially overlaying the temperature probe and the insulating cavity. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has an ice accretion feature arranged between the scoop feature and the leading edge of the airfoil body. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the scoop feature terminates at a tip surface aperture, wherein the tip surface aperture fluidly couples the scoop feature to the temperature probe. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the scoop feature spans an insulating cavity inlet defined by the tip surface of the airfoil body, and that the insulating cavity inlet fluidly couples the scoop feature to the insulating cavity. 
     A gas turbine engine is also provided. The gas turbine engine includes a compressor section with a compressor inlet; a combustor section in fluid communication with the compressor section; a turbine section in fluid communication with the combustor section; and a sensor as describe above, the sensor being a P2T2 sensor supported within the compressor inlet of the gas turbine engine. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a tip surface extending to the trailing edge of the airfoil body, that the airfoil body defines a temperature sense chamber between the insulating cavity and the trailing edge of the airfoil body, and that the temperature probe extends into the temperature sense chamber. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body defines a temperature sense chamber between the insulating cavity and the trailing edge of the airfoil body, that the temperature probe extends into the temperature sense chamber, and that the airfoil body has a tip surface defining therein a scoop feature, the scoop feature axially overlaying the temperature probe and the insulating cavity. 
     In addition to one or more of the features described above, or as an alternative, further examples of the sensor may include that the airfoil body has a tip surface defining therein a scoop feature, that the scoop feature axially overlays the temperature probe and the insulating cavity, and that the tip surface extends to the trailing edge of the airfoil body. 
     A method of making a sensor includes forming an airfoil body defining a sensor axis and an insulating cavity using an additive manufacturing technique, the airfoil body extending between a leading edge and a trailing edge of the airfoil body, using an additive manufacturing technique, forming the airfoil body including defining a heater element seat extending axially through the airfoil body between the leading edge and the trailing edge of the airfoil body, and forming the airfoil body including defining a temperature probe seat extending axially through the airfoil body between the insulating cavity and the trailing edge of the airfoil body. The method also includes positioning a heater element within the heater element seat and positioning a temperature probe within the temperature probe seat. 
     A method of thermally separating a temperature probe from a heater element is additionally provided. The method includes, at a sensor as described above, heating the leading edge of the airfoil body with the heater element; thermally separating the temperature probe from the heater element by flowing fluid from the environment external to the sensor through the insulating cavity; flowing further fluid from the environment external to the sensor across the temperature probe; and measuring temperature of the fluid flowing across the temperature probe with the temperature probe. 
     Technical effects of the present disclosure include providing sensors with the capability to thermally separate a temperature probe positioned within the sensor from a heater element positioned within the sensor. In certain examples the present disclosure provides the capability to heat the during operation in icing conditions and provide temperature measurements with limited (and in certain examples) no measurement error due to operation of the heater element. In accordance with certain examples the sensors described herein have the capability to shunt air heated by a heater element through the airfoil body of the sensor, limiting communication of heated air to the temperature probe of the sensor. In accordance with certain examples sensors described herein have the capability to separate, impound, and melt ice crystals ingested within the sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a schematic view of a sensor constructed in accordance with the present disclosure, showing a gas turbine engine with a pressure and temperature sensor supported within a compressor inlet of the gas turbine engine; 
         FIG.  2    is a perspective view of the sensor of  FIG.  1    according to an example, showing a mount and an airfoil body of the sensor; 
         FIG.  3    is a cross-sectional view of the sensor of  FIG.  1    according to the example, showing a pressure channel defined chordwise between a heater element seat and a temperature probe within the airfoil body of the sensor; 
         FIG.  4    is a cross-sectional side view of the sensor of  FIG.  1    according to the example, showing a pressure conduit seated within the pressure channel defined within the airfoil body; 
         FIG.  5    is another side view of a portion of the sensor of  FIG.  1    according to the example, showing a second face of the blade body defining a second face outlet vent fluidly coupled to tip surface aperture at a location forward of the temperature probe and temperature sense chamber; 
         FIGS.  6  and  7    are cross-sectional views of a portion of the sensor of  FIG.  1    according to the example, showing an inlet segment of the pressure channel connecting a pressure inlet to the expansion chamber within the airfoil body; 
         FIGS.  8  and  9    are perspective views of a portion of the sensor of  FIG.  1    according to the example, showing inlet vents and outlet vents of the insulating cavity in faces of the airfoil body connected to tip surface inlet of the insulating cavity; 
         FIGS.  10  and  11    are perspective and partial perspective views of the sensor of  FIG.  1    according to the example, showing an ice accretion feature extending from the tip surface of the airfoil body of the sensor; 
         FIGS.  12 - 14    are perspective views of the sensor of  FIG.  1    according to an example of the sensor without the ice accretion feature, showing ice accretion initiating at a location aft of the leading edge and growing toward the leading edge of the airfoil body; 
         FIG.  15    is a perspective view of the sensor of  FIG.  1    according to the example, showing ice accreting from a location proximate the leading edge of the airfoil body; 
         FIGS.  16  and  17    are partial front view of the sensor of  FIG.  1    according the first and a second example, showing ice accretion features with a fin-like body and a spherical body, respectively; 
         FIG.  18    is a block diagram of a method of making sensor in accordance with the present disclosure, showing operations of the method according to an illustrative and non-limiting example of the method; and 
         FIG.  19    is a block diagram of a method of thermally partitioning a sensor in accordance with the present disclosure, showing operations of the method according to an illustrative and non-limiting example of the method. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of a sensor  100  in accordance with the disclosure is shown in  FIG.  1    and is designated generally by reference character  100 . Other embodiments of sensors, gas turbine engines, methods of making sensors, and methods of thermally separating temperature probes from heater elements in pressure and temperature sensors are provided in  FIGS.  2 - 19   , as will be described. The sensors and related methods described herein can be used for measuring pressure and temperature of air using sensors exposed to icing conditions, such as in P2T2 probes on aircraft, though the present disclosure is not limited to P2T2 probes or to pressure and temperature sensing on aircraft in general. 
     Referring to  FIG.  1   , an aircraft  10  is shown. The aircraft  10  includes a gas turbine engine  12  and the pressure and temperature sensor  100 . The gas turbine engine  12  includes a compressor section  14 , a combustor section  16 , a turbine section  18  and an engine controller  20 . The compressor section  14  has a compressor inlet  22  and is arranged to compress an ambient air flow  24  ingested from the external environment  26  to generate a compressed air flow  28 . The combustor section  16  is fluidly coupled to the compressor section  14  and is arranged to generate a high-pressure combustion product flow  30  using the compressed air flow  28 . The turbine section  18  is fluidly coupled to the combustor section  16  and is arranged to extract work from the high-pressure combustion product flow  30  as the high-pressure combustion product flow  30  traverses the turbine section  18 . In certain examples the gas turbine engine  12  is an aircraft main engine. In accordance with certain examples the gas turbine engine  12  is an auxiliary power unit for an aircraft. 
     The pressure and temperature sensor  100  is seated within the compressor inlet  22  of the compressor section  14  of the gas turbine engine  12  and is in communication with the engine controller  20  to provide pressure and temperature information to the engine controller  20 . In certain examples a pressure transducer  32  couples the pressure and temperature sensor  100  to the engine controller  20  to generate a pressure signal  34  indicating pressure of the ambient air flow  24 . In accordance with certain examples a temperature transducer  36  couples the pressure and temperature sensor  100  to the engine controller  20  to generate a temperature signal  38  indicating temperature of the ambient air flow  24 . It is contemplated that the pressure and temperature sensor  100  can be a total pressure and a total temperature sensor  100 , e.g., a P2T2 sensor fixed to the gas turbine  12  to measure compressor (or fan) inlet pressure and temperature or a P25T25 sensor fixed to the gas turbine engine  12  to measure pressure and temperature at a location fluidly between low-pressure and high-pressure segments of compressor section  14 . 
     The engine controller  20  is programmed to monitor pressure and/or temperature of the ambient air flow  24  using the pressure signal  34  and/or temperature signal  38 . It is also contemplated that the engine controller  20  be programmed to control operation of the gas turbine engine  12  using the pressure signal  34  and/or temperature signal  38 . In certain examples the engine controller  20  includes a full-authority digital engine controller (FADEC) device. 
     As will be appreciated by those of skill in the art in view of the present disclosure, the ambient air flow  24  can contain entrained ice crystals and/or super-cooled moisture  40 . As will also be appreciated by those of skill in the art in view of the present disclosure, entrained ice crystals and/or super-cooled moisture can interfere with operation of the pressure and temperature sensor  100 . For example, ice crystals entrained within the ambient air flow  24  can potentially interrupt communication of pressure of the ambient air flow  24  to the engine control and/or introduce anomalies into the pressure signal and/or temperature signal generated by the pressure and temperature sensor  100 . Super-cooled moisture entrained within the ambient air flow  24  can also cause ice accretion within and on the exterior of the pressure and temperature sensor  100 , such as during flight of the aircraft  10  in icing conditions, potentially also interrupt communication of pressure of the ambient air flow  24  to the engine control and/or introduce anomalies into the pressure signal and/or temperature signal generated by the pressure and temperature sensor  100 . To limit (or prevent entirely) interruption and/or measurement anomalies the pressure and temperature sensor  100  is provided with one or more ice protection features, as will be described. 
     With reference to  FIGS.  2 - 7   , the pressure and temperature sensor  100  is shown. As shown in  FIG.  2   , the pressure and temperature sensor  100  includes a mount  102  and an airfoil body  104 . The mount  102  has a fluid fitting  106 , an electrical connector  108 , a flange portion  110  and a pedestal portion  112 . The fluid fitting  106  and the electrical connector  108  are seated to the mount a side the flange portion  110  opposite the airfoil body  104 . The flange portion  110  has a fastener pattern  113  defined therethrough for fixation of the pressure and temperature sensor  100  within the compressor inlet  22  (shown in  FIG.  1   ) of the compressor section  14  (shown in  FIG.  1   ). The pedestal portion  112  extends from the flange portion  110  in a direction opposite both the fluid fitting  106  and the electrical connector  108 . The airfoil body  104  is fixed with the pedestal portion  112 . 
     The airfoil body  104  extends axially from the mount  102 , defines a sensor axis  114 , and has a leading edge  116 , a trailing edge  118 , a first face  120 , a second face  122  and a tip surface  124 . The first face  120  extends between the leading edge  116  and the trailing edge  118  of the airfoil body  104  and faces in a direction opposite that of the electrical connector  108 . The second face  122  extends between the leading edge  116  and the trailing edge  118  of the airfoil body  104  and faces in a direction opposite that of the fluid fitting  106 . The tip surface  124  axially spans the leading edge  116  and the trailing edge  118 , laterally spans the first face  120  and the second face  122  and intersects the sensor axis  114 . In certain examples the airfoil body  104  defines the sensor axis  114 . 
     As shown in  FIG.  3   , the airfoil body  104  has pressure inlet  126 . The airfoil body  104  also defines a heater element seat  128  and a pressure channel  130  within its interior. The pressure inlet  126  is arranged on the leading edge  116  of the airfoil body  104  and is in fluid communication with the pressure channel  130 . The heater element seat  128  is defined chordwise between the leading edge  116  of the airfoil body  104  and the trailing edge  118  of the airfoil body  104 , extends from the mount  102  and axially within the airfoil body  104 , and has a heater element seat terminus  132  located axially between the pressure inlet  126  and the tip surface  124  of the airfoil body  104 . A heater element  134  is positioned within the heater element seat  128  and is electrically connected by a heater element lead  136  (shown in  FIG.  4   ) to the electrical connector  108  for heating a heated portion  138  of the airfoil body  104 . In certain examples the heater element seat terminus  132  is arranged within the ice accretion feature  192 . 
     As shown in  FIGS.  4  and  5   , the pressure channel  130  is defined along the chord of the airfoil body  104  between the heater element seat  128  and the trailing edge  118  of the airfoil body  104  and includes an outlet segment  140  and an expansion chamber  142 . The outlet segment  140  extends axially within the airfoil body  104  and seats therein a pressure conduit  144 . The pressure conduit  144  extends from the airfoil body  104  through the mount  102  to the fluid fitting  106  (shown in  FIG.  2   ), and therethrough fluidly couples the outlet segment  140  of the pressure channel  130  with the pressure transducer  32  (shown in  FIG.  1   ). As also shown in  FIG.  4   , an ice accretion feature terminus  105  is located chordwise between the heater element  134  and the temperature probe  158 . 
     As shown in  FIG.  5   , the expansion chamber  142  extends axially within the airfoil body  104  between a first end  146  and a second end  148  within the airfoil body  104 . Between the first end  146  and the second end  148  the expansion chamber  142  defines an expansion chamber flow area  150  (shown in  FIG.  7   ). It is contemplated that the expansion chamber flow area  150  be larger than an outlet segment flow area  153  (shown in  FIG.  7   ) to slow the velocity of air flowing through the expansion chamber  142  relative velocity of air flowing through the outlet segment  140 . As will be appreciated by those of skill in the art in view of the present disclosure, slowing velocity of air flowing through the expansion chamber  142  limits the capability of the air to carry entrained ice crystals and/or super-cooled moisture  40  to the outlet segment  140 . Slowing air velocity entrained ice crystals to separate from the air within the expansion chamber  142 , the entrained ice collecting at the second end  148  of the expansion chamber  142  for melting using heat generated by the heater element  134  (shown in  FIG.  7   ). Separation, collection, and melting of ice crystals entrained within air entering the airfoil body  104  reduces (or eliminates entirely) the probability that the entrained ice interrupts and induces anomalies into the pressure signal  34  (shown in  FIG.  1   ) generated by the pressure transducer  32  (shown in  FIG.  1   ). 
     As shown in  FIGS.  6  and  7   , the pressure channel  130  also includes an inlet segment  152 . The inlet segment  152  fluidly couples the pressure inlet  126  to the expansion chamber  142 . More specifically, the inlet segment  152  traces an arcuate path  154  chordwise along the airfoil body  104  between the pressure inlet  126  and the second end  148  (shown in  FIG.  5   ) of the expansion chamber  142 . The arcuate path  154  extends laterally between the heater element seat  128  and the first face  120  of the airfoil body  104  such that air traversing the inlet segment  152  passes in close proximity to the heater element  134 . Close proximity between the air and the heater element  134  increases likelihood that ice entrained within the air melts prior to arriving at the second end  148  of the expansion chamber  142 , also reducing (or eliminating entirely) that the entrained ice interrupts and induces anomalies into the pressure signal  34  (shown in  FIG.  1   ) generated by the pressure transducer  32  (shown in  FIG.  1   ). It is contemplated that the inlet segment  152  be substantially orthogonal relative to the heater element  134  and/or the expansion chamber  142 . 
     In certain examples the inlet segment  152  defines an inlet segment flow area  156  that is smaller than expansion chamber flow area  150 . Sizing the inlet segment flow area  156  such that it is smaller than the expansion chamber flow area  150  causes flow velocity of air traversing the inlet segment  152  to decrease upon entry to the second end  148  of the expansion chamber  142 . This also causes entrained ice to separate from the air within the second end  148  of the expansion chamber  142 , the entrained ice collecting at the second end  148  of the expansion chamber  142  reducing (or eliminating entirely) that the entrained ice interrupts and induces anomalies into the pressure signal  34  (shown in  FIG.  1   ) generated by the pressure transducer  32  (shown in  FIG.  1   ). 
     With reference to  FIGS.  5 ,  8  and  9   , it is contemplated that the pressure and temperature sensor  100  includes a temperature probe  158 . As shown in  FIG.  5   , the airfoil body  104  defines a temperature probe seat  160  chordwise between the expansion chamber  142  and the trailing edge  118  of the airfoil body  104 . The temperature probe seat  160  extends axially between the mount  102  and a temperature sense chamber  162  such that a tip portion of the temperature probe  158  is arranged within the temperature sense chamber  162 . A temperature probe lead  164  (shown in  FIG.  4   ) electrically connects the temperature probe  158  to the electrical connector  108  and therethrough with the temperature transducer  36  (shown in  FIG.  1   ). 
     As shown in  FIGS.  8  and  9   , the temperature sense chamber  162  is in fluid communication with the external environment  26  (shown in  FIG.  1   ) through a first face aperture  166 , a second face aperture  168 , and a tip surface aperture  170 . The first face aperture  166  extends through the first face  120  of the airfoil body  104  and fluidly couples the temperature sense chamber  162  to the external environment  26  through the first face aperture  166 . The second face aperture  168  extends through the second face  122  and fluidly couples the temperature sense chamber  162  to the external environment  26  through the second face aperture  168 . The tip surface aperture  170  extends through the tip surface  124  and fluidly couples the temperature sense chamber  162  through the tip surface aperture  170 . 
     With continuing reference to  FIG.  5   , the airfoil body  104  defines within its interior an insulating cavity  172 . The insulating cavity  172  is defined chordwise between the temperature probe seat  160  and the expansion chamber  142 . The insulating cavity  172  also extends axially between the tip surface  124  and the mount  102  to provide a thermal break between the temperature probe seat  160  and the heater element seat  128  to limit (or eliminate entirely) thermal communication between the heater element  134  (show in  FIG.  7   ) and the temperature probe  158 . The insulating cavity  172  has an insulating cavity inlet  174 , an insulating cavity inlet channel  176 , and an insulating cavity tip chamber  178 . The insulating cavity  172  also has an insulating cavity interconnect channel  180 , an insulating cavity base chamber  182 , a first face outlet vent  184  (shown in  FIG.  8   ), and a second face outlet vent  186 . 
     The insulating cavity inlet  174  is defined chordwise between the tip surface aperture  170  and the leading edge  116  of the airfoil body  104 . The insulating cavity inlet channel  176  is in fluid communication with the external environment  26  (shown in  FIG.  1   ) through the insulating cavity inlet  174  and extends from the tip surface  124  to the insulating cavity tip chamber  178 . The insulating cavity tip chamber  178  defines a volume within the airfoil body  104  extending forward from the temperature sense chamber  162  and toward the leading edge  116  of the airfoil body  104 . It is contemplated that the insulating cavity tip chamber  178  axially separate the tip surface  124  of the airfoil body  104  from the second end  148  of the expansion chamber  142 . 
     The insulating cavity interconnect channel  180  is in fluid communication with the insulating cavity tip chamber  178 , is defined chordwise within the airfoil body  104  between the temperature sense chamber  162  and the expansion chamber  142 , and extends axially within the airfoil body  104  toward the mount  102 . The insulating cavity base chamber  182  is in fluid communication with the insulating cavity interconnect channel  180 , is defined chordwise between the temperature probe seat  160  and the expansion chamber  142 , and extends axially upwards through the airfoil body  104  toward the mount  102 . It is contemplated that the insulating cavity base chamber  182  extend upwards to a location between first face outlet vent  184  and the mount  102 . 
     The first face outlet vent  184  extends through the first face  120  of the airfoil body  104  and fluidly connects the insulating cavity base chamber  182  to the external environment  26  (shown in  FIG.  1   ). The second face outlet vent  186  extends through the second face  122 , is laterally opposite the first face outlet vent  184  such that the second face outlet vent  186  is in registration with the first face outlet vent  184 , and fluidly connects the insulating cavity base chamber  182  of the insulating cavity  172  to the external environment  26 . In certain examples the first face outlet vent  184  is a first face outlet vent  184  axially stacked with a first face second outlet vent  188  also fluidly connecting the insulating cavity base chamber  182  of the insulating cavity  172  to the external environment  26 . In accordance with certain examples the second face outlet vent  186  is a second face first outlet vent  186  axially stacked with a second face second outlet vent  190  also fluidly connecting the insulating cavity base chamber  182  to the external environment  26 . 
     With reference to  FIGS.  10 - 17   , examples of the pressure and temperature sensor  100  including an ice accretion feature  192  are shown. As shown in  FIG.  10   , the airfoil body  104  has an ice accretion feature  192 . The ice accretion feature  192  extends from the tip surface  124  in a direction opposite the mount  102  and is defined chordwise at the leading edge  116  of the airfoil body  104 . More specifically, the ice accretion feature  192  extends from the tip surface  124  at a location chordwise forward of the insulating cavity inlet  174  of the insulating cavity  172  adjacent the heated portion  138  (shown in  FIG.  5   ) of the airfoil body  104 . Relative to the inlet  22  (shown in  FIG.  1   ) of the compressor section  14  (shown in  FIG.  1   ) of the gas turbine engine  12  (shown in  FIG.  1   ), the ice accretion feature  192  extends downward relative to gravity when the aircraft  10  (shown in  FIG.  1   ) is in straight and level flight. 
     As shown in  FIGS.  12 - 15   , during operation in icing conditions ambient air containing super-cooled moisture, e.g., the ambient air flow  24 , flows across the tip surface  124  of the airfoil body  104 . As shown in  FIG.  12   , ice accretion typically begins at an initiation location  194  chordwise along the airfoil body  104  between the trailing edge  118  and the leading edge  116  of the airfoil body  104 . The initiation location  194  is generally located at the trailing edge of the tip surface aperture  170  due to the collection efficiency at that location. As shown in  FIGS.  13  and  14   , once initiated, entrained ice crystals and/or super-cooled moisture  40  accretes in a direction forward along the airfoil body  104  relative to the insulating cavity inlet  174  and toward the leading edge  116  of the airfoil body  104 . Ice accretion generally continues until the mass of the ice formation is sufficiently large that the stress exerted on the ice formation causes the ice formation to fraction, the accretion resulting from entrained ice crystals and/or super-cooled moisture  40  thereafter separating from the airfoil body  104 . 
     As shown in  FIG.  15   , when included on the airfoil body  104 , the ice accretion feature  192  causes ice accretion to initiate at a location  197  proximate the leading edge  116  in relation to examples of the airfoil body  104  not having the ice accretion feature  192 . Without being bound by a particular theory it is believed that air flowing across the ice accretion feature  192  creates a relatively high collection efficiency location. The higher collection efficiency created by the ice accretion feature  192  causes super-cooled moisture within the air flowing across the airfoil body  104  to preferentially accrete forward of the tip surface aperture  170  at a location between the insulating cavity inlet  174  and the leading edge  116  of the airfoil body  104 . Preferentially accreting ice forward of the tip surface aperture  170  in turn reduces the collection efficiency at the tip surface aperture  170  and prolongs the time interval during which the tip surface aperture  170  remains ice-free during flight in icing conditions, limiting (or eliminating entirely) the tendency of accreted ice to accrete within the temperature sense chamber  162  where ice accretion could otherwise interrupt the ability of the temperature probe  158  to accurate measure temperature of the ambient air flow  24  (shown in  FIG.  1   ). 
     As shown in  FIG.  16   , in certain examples the ice accretion feature  192  can define a fin body  195  having a fin body width  196  that is smaller than an airfoil width  101  of the airfoil body  104 . As shown in  FIG.  17   , it is also contemplated that the ice accretion feature  192  can define a spherical body  198  having a spherical body width  103  that is greater the airfoil width  101  of the airfoil body  104 . As will be appreciated by those of skill in the art in view of the present disclosure, larger ice accretion features tend to reduce the collection efficiency at the tip surface aperture  170  as compared to ice accretion features having smaller widths. The spherical body  198  therefore produces smaller ice accretions at the tip surface aperture  170  than the fin body  195  when subjected to an otherwise identical set of icing conditions. 
     With reference to  FIG.  18   , a method  200  of making a sensor, e.g., the pressure and temperature sensor  100  (shown in  FIG.  1   ), is shown. The method  200  includes forming an airfoil body defining a sensor axis and having a leading edge, a trailing edge, and defining therein an insulating cavity, e.g., the insulating cavity  172  (shown in  FIG.  5   ), using an additive manufacturing technique, as shown with box  210 . Examples of suitable additive manufacturing technique includes laser sintering and powder bed fusion techniques. As will be appreciated by those of skill in the art in view of the present disclosure, additive manufacturing techniques allow the airfoil body to be made as a single monolithic structure with areas of the internal passages being larger than near where the passages pass through external surfaces of the airfoil body. This geometry effectively prevents molding of the body since core could not be pulled during the molding process to form larger area flow passages deeper within the body. It also contemplated that the airfoil body can be formed using a casting technique and/or subtractive technique and remain within the scope of the present disclosure. 
     As shown with box  212 , it is contemplated that forming the airfoil body include defining a heater element seat, e.g. the heater element seat  128  (shown in  FIG.  4   ), extending axially through the airfoil body (e.g., at a chordwise location) between the leading edge and the trailing edge of the airfoil body. As shown with box  214 , it is also contemplated that forming the airfoil body include defining a temperature probe seat, e.g., the temperature probe seat  160  (shown in  FIG.  5   ), extending axially through the airfoil body between the heater element seat and the insulating cavity to thermally separate the heater element form the temperature probe. As shown with box  216 , it is further contemplated that forming the airfoil body include defining the insulating cavity, e.g., the insulating cavity  172  (shown in  FIG.  5   ), between the heater element seat and the temperature probe seat. 
     In certain examples forming the airfoil body includes defining a pressure channel, e.g., the pressure channel  130  (shown in  FIG.  3   ), between the insulating cavity and the heater probe seat, as shown with box  218 . In accordance with certain examples, forming the airfoil body can include forming an ice accretion feature, e.g., the ice accretion feature  192  (shown in  FIG.  2   ), axially overlapping the heater element seat, as shown with box  220 . 
     As shown with box  230 , the method  200  also includes positioning a heater element, e.g., the heater element  134  (shown in  FIG.  3   ), within the heater element seat. As shown with box  240 , the method additionally includes positioning a temperature probe, e.g., the temperature probe  158  (shown in  FIG.  5   ), within the temperature probe seat. It is also contemplated that, in accordance with certain examples, that the method  200  include fixing the airfoil body to a mount, e.g., the mount  102  (shown in  FIG.  2   ), as shown with box  250 . 
     With reference to  FIG.  19   , a method  300  of thermally separating a temperature probe and a heater element within a sensor, e.g., the pressure and temperature sensor  100  (shown in  FIG.  1   ), is shown. The method  300  includes heating a leading edge of an airfoil body with a heater element, e.g., the leading edge  116  (shown in  FIG.  2   ) of the airfoil body  104  (shown in  FIG.  2   ) with the heater element  134  (shown in  FIG.  3   ), as shown with box  310 . The temperature probe is thermally separated from the heater element by flowing fluid from the external environment through an insulating cavity defined within the airfoil body between the heater element and the temperature probe, e.g., air traversing the ice accretion feature  192  (shown in  FIG.  5   ) through the insulating cavity  172  (shown in  FIG.  5   ), as shown with box  320 . The method  300  additionally includes flowing further fluid, e.g., air from the external environment  26  (shown in  FIG.  1   ) representative of temperature in the external environment, across the temperature probe, as shown with box  330 . Temperature of the air then measured with the temperature probe, as shown with box  340 . 
     Sensors can be used to measure pressure and temperature of air ingested by gas turbine engines. Such sensors can protrude into the airflow entering the compressor section of the gas turbine engine, or between the low-pressure and high-pressure segments of compressors, to provide pressure and temperature information. The pressure and temperature measurements can be employed, for example, for monitoring the operating conditions of the gas turbine engine as well as for controlling the gas turbine engine. 
     In some sensors ice and super-cooled moisture entrained within the airflow entering the sensor can interfere with the operation of the sensor. For example, ice crystals can be driven into passageways defined within such sensors. Once within the sensor passageways the ice crystals can interrupt operation of the sensor and/or cause the sensor to provide anomalous sensor measurements. Super-cooled moisture can also accrete on the exterior of such sensors, potentially blocking entrances and/or exits from the passageways defined within the sensor. Such ice accretions can also interrupt operation of the sensor and/or cause the sensor to provide anomalous sensor measurements. And while sensor heating can be employed to mitigate the effects of either (or both) entrained ice crystals and super-cooled moisture, heat from sensor heating can itself introduce error into measurements provided by certain sensors. 
     In examples described herein sensors have pressure channels therein with inlet segments in close proximity to a heater element. The close proximity of the inlet segment enables heat from the heater element to melt ice crystals entrained within air traversing the inlet segment of the pressure passage, limiting (or eliminating entirely) the probability of entrained ice crystals from interfering with operation of the sensor. In accordance with certain examples sensors described herein have pressure channels with expansion chambers. The expansion chambers slow velocity of air traversing the pressure channel, separating and impounding the entrained ice crystals such heat from the heater element can melt the ice. Impounding and/or melting the separated ice crystals limits (or eliminates entirely) the probability that the entrained ice crystals will interfere with operation of the sensor. 
     It is contemplated that sensors described herein include an insulating cavity. The insulating cavity is defined chordwise between the leading edge and the trailing edge of the airfoil body at location between the heater element and a temperature probe seated in the airfoil body. So situated the insulating cavity limits (or prevents entirely) heat from the heater element reaching the temperature probe, the insulating cavity thereby reducing (or eliminating entirely) probability that heat from the heater element introduce error into temperature measurements acquired by the temperature probe. 
     It is also contemplated that, in accordance with certain examples, that the airfoil body have an ice accretion feature. The ice accretion feature is arranged such that ice accreted from super-cooled moisture traversing the airfoil body of the sensor preferentially accrete at a location chordwise forward inlets and/or vents defined within the airfoil body and in communication with the temperature probe and insulating cavity, respectively. This increases the time interval during exposure to icing conditions during which the sensor can reliably provide temperature data, limiting (or eliminating entirely) the probability of interruption and/or measurement anomalies due to ice accretion on the exterior of the sensor. Further examples of the ice accretion are arranged for shedding accreted ice relatively quickly and while the ice accretion is relatively small. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.