CERAMIC PROBE HEAD FOR AN AIR DATA PROBE
A probe head for an air data probe includes a ceramic body and a heater embedded within the ceramic body.
This application is a continuation of U.S. application Ser. No. 16/714,045, filed on Dec. 13, 2019, entitled “CERAMIC PROBE HEAD FOR AN AIR DATA PROBE,” the disclosure of which is incorporated by reference in its entirety.
BACKGROUNDThe present disclosure relates generally to air data probes, and in particular, to probe heads.
Air data probes are mounted to an exterior of an aircraft in order to gain exposure to external airflow for measuring air data parameters. Thus, air data probes are exposed to the environmental conditions exterior to the aircraft, which are often cold. As such, heaters are positioned within air data probes to ensure the air data probes function properly in liquid water, ice crystal, and mixed phase icing conditions. It can be difficult to successfully arrange the heater within the probe head of an air data probe.
SUMMARYA probe head for an air data probe includes a ceramic body and a heater embedded within the ceramic body.
An air data probe includes a strut, a probe head connected to the strut, and a transition piece having a first end connected to the probe head and a second end connected to the strut such that the transition piece connects the probe head to the strut. The probe head includes a ceramic body and a heater embedded within the ceramic body.
In general, the present disclosure describes an air data probe that has a probe head made up of ceramic layers and heater layers that undergo a high temperature co-fired ceramic process such that the probe head is ceramic with embedded heaters. The probe head is attached to a strut via a transition piece that acts as the high stress area of the air data probe and includes water trap features to prevent ice and water accumulation within the probe. As a result, heaters are integrated into the probe head for more efficient and tailored, or customized, heat distribution to reduce required power and heater failure and increase heater reliability, strength, and response time.
Air data probe 10 may be a pitot probe, a pitot-static probe, or any other suitable air data probe. Probe head 12 is the sensing head of air data probe 10. Probe head 12 is a forward portion of air data probe 10. Probe head 12 has an opening at a first end of probe head 12. Probe head 12 is connected to a first end of transition piece 14 near a second end of probe head 12. A second end of transition piece 14 is connected to a first end of strut 16. As such, probe head 12 is connected to strut 16 via transition piece 14. Strut 16 is blade-shaped. Internal components of air data probe 10 are located within strut 16. Strut 16 is adjacent mounting flange 18. A second end of strut 16 is connected to mounting flange 18. Mounting flange 18 makes up a mount of air data probe 10. Mounting flange 18 is connectable to an aircraft.
Air data probe 10 is configured to be installed on an aircraft. Air data probe 10 may be mounted to a fuselage of the aircraft via mounting flange 18 and fasteners, such as screws or bolts. Strut 16 holds probe head 12 away from the fuselage of the aircraft to expose probe head 12 to external airflow. Transition piece 14 connects probe head 12 to strut 16. Probe head 12 takes in air from surrounding external airflow and communicates air pressures pneumatically through internal components and passages of probe head 14 and strut 16 through a pressure fitting (not shown). Pressure measurements are communicated to a flight computer and can be used to generate air data parameters related to the aircraft flight condition.
Air data probe 10 has probe head 12 connected to transition piece 14. Transition piece 14 is also connected to strut 16. As such, transition piece 14 is between probe head 12 and strut 16 and connects probe head 12 to strut 16. Strut is connected to mounting flange 18, which connects to an aircraft. Electrical wires 19A and 19B connect to probe head 12 and extend through transition piece 14, strut 16, and mounting flange 18 to an interior of the aircraft.
Probe head 12 has a ceramic body and is heated. Probe head 12 is rod-like and has first end 20 at an upstream end of probe head 12 and second end 22 at a downstream end of probe head 12, which is opposite first end 20. Tip 24 is at first end 20 of probe head 12. Tip 24 defines an opening at first end 20 of probe head 12. Exterior surface 26 is an outer surface of probe head 12 that extends from first end 20 to second end 22. Interior surface 28 is an inner surface of probe head 12 that extends from first end 20 to second end 22. Exterior surface 26 forms shoulder 30 near second end 22. An outer diameter of probe head 12 from shoulder 30 to second end 22 is less than an outer diameter of probe head 12 from shoulder 30 to first end 20. The outer diameter of probe head 12 from shoulder 30 to first end 20 is about constant. The outer diameter of probe head 12 from shoulder 30 to second end 22 may decrease or vary.
Interior surface 28 forms passageway 32, which extends from first end 20 to second end 22. As such, passageway 32 extends an entire length of probe head 12. Passageway 32 begins at the opening defined by tip 24 at first end 20. Interior surface 28 also forms lip 34. Passageway 32 has a smaller cross-sectional area at lip 34. First post 36 is a rod having a first end connected to interior surface 28 and a second end connected to interior surface 28 such that first post 36 extends through a center of passageway 32. Second post 38 is a rod having a first end connected to interior surface 28 and a second end connected to interior surface 28 such that second post 38 extends through a center of passageway 32 perpendicular to first post 36. First post 36 is upstream of second post 38. In this embodiment, probe head 12 has two posts, first post 36 and second post 38. In alternate embodiments, probe head 12 may have one post, three posts, or any suitable number of posts. Drain holes 40 are holes that extend from interior surface 28 to exterior surface 26 downstream of first post 36 and second post 38 and upstream of lip 34. In this embodiment, air data probe 10 includes two drain holes 40. In alternate embodiments, air data probe 10 may include any number of drain holes 40. Lip 34, first post 36, second post 38, and drain holes 40 act as a water management feature of probe head 12. A metalized surface 42 is at second end 22 of probe head 12. Metalized surface 42 at second end 22 connects to electrical wires 19A and 19B. A metalized surface 42 is also at shoulder 30 of probe head 42.
Transition piece 14 is made of a ductile material, such as nickel. Transition piece 14 has first end 44 at an upstream end of transition piece 14 and second end 46 at a downstream end of transition piece 14. First end 44 of transition piece 14 is connected to probe head 12 at shoulder 30 via metalized surface 42 of shoulder 30. Second end 46 of transition piece 14 is connected to strut 16. Socket 48 is an opening that extends into transition piece 14 from first end 44. Second end 22 of probe head 12 extends within socket 48 of transition piece 14. Electrical wires 19A and 19B connect to metalized surface 42 at second end 22 of probe head 12 within socket 48 of transition piece 14. Passageway 50 of transition piece 14 extends from socket 48 to second end 46 of transition piece 14. As such, passageway 32 of probe head 12, socket 48 of transition piece 14, and passageway 50 of transition piece 14 are connected, or are in fluid communication.
Transition piece 14 connects ceramic probe head 12 to metal strut 16. Transition piece 14 is the high stress area of air data probe 10. Electrical wires 19A and 19B connected to metalized surface 42 at second end 22 of probe head 12 provides electrical connection from within an aircraft to probe head 12 for supplying heat to heaters within probe head 12. As such, metalized surfaces 42 allow for electrical and mechanical connections of probe head 12.
As external airflow enters probe head 12 at first end 20 and flows through passageway 32, water and ice particles in the airflow hit and are knocked down by first post 36, second post 38, and lip 34. Because probe head 12 is heated, first post 36 and second post 38 are heated, and knocked down ice particles melt within passageway 32. Lip 34 prevents the water from moving further downstream within probe head 12. Water then drains out of passageway 32 via drain holes 40 to exit probe head 12. Therefore, first post 36, second post 38, and lip 34 prevent ingested airflow and contaminants within the airflow from having a straight path through probe head 12.
Transition piece 14 allows ceramic probe head 12 to connect to metal strut 16. Transition piece 14 is made of nickel and accounts for different thermal expansion between the ceramic body of probe head 12 and metal strut 16. Transition piece 14 prevents probe head 12 from detaching from strut 16, and potentially moving backward into the engine and causing damage. Because transition piece 14 is the high stress area, or weak point, of air data probe 10 and is made of a ductile material, transition piece 14 also absorbs impacts, such as from bird strikes or hail, and prevents the more brittle ceramic probe head 12 from fracturing and separating from air data probe 10. First post 36, second post 38, and lip 34 prevent water from moving through air data probe 10 and affecting the accuracy of pressure measurements.
Probe head 12 has the same structure and function as probe head 12 described with respect to
Heater 54 is embedded within ceramic body 52 of probe head 12 via a high temperature co-fired ceramic process, where heater 54 (the conductor) and ceramic body 52 (the insulator) are fired at the same time to result in a fully dense material. More specifically, traces of heater 54 are applied to ceramic body 52 as an unrolled tape, which is wound around a mandrel, and heater 54 and ceramic body 52 are fired to turn from pliable separate materials to a hard solid material. As such, probe head 12 has about zero porosity. First post 36 and second post 38, which are made of the same material as ceramic body 52, may then be connected to ceramic body 52, such as via brazing or gluing (for example, with a ceramic glue or any other suitable material). Metalized surfaces 42 are applied to bores that receive electrical wires 19A and 19B at second end 22 of ceramic body 52 and to shoulder 30 of ceramic body 52. Electrical wires 19A and 19B are soldered to metalized surface 42 at second end 22 to achieve a hermetically sealed electrical connection. A metalized surface 42 is applied to shoulder 30 prior to brazing probe head 12 to first end 44 of transition piece 14, such that ceramic probe head 12 can connect to transition piece 14 via metalized surface 42 of shoulder 30.
Air data probe 10 is installed on an aircraft and subjected to icing conditions during flight. Ceramic body 52 of probe head 12 acts as both the substrate of heater 54 and the structure of probe head 12. Heater 54 is encapsulated in ceramic body 52. Heater 54 provides heat to air data probe 10 to prevent and remove ice growth. Different regions of air data probe 10 may require different levels of heat. As such, heater 54 varies in thickness, which varies resistance, and may have multiple layers, such that more or less heat can be distributed based on the heating needs of probe head 12. Heater 54 receives power via metalized surface 42 at second end 22. Vias 56 act as electrical connectors between different layers of heater 54 to distribute power. Ceramic body 52 allows for high Watt densities and can change temperature rapidly.
Traditionally, heaters are brazed into air data probes. As such, manufacturing limitations affect where and how heaters can be placed on the air data probe. For example, arranging heaters near the tip of the probe head can be difficult, which makes heating the tip difficult. Brazed heaters also fail due to corrosion, thermal fatigue, and oxidation.
Probe head 12 formed by a high temperature co-fired ceramic process allows for more flexibility with respect to where heater 54 is positioned within probe head 12 and how much heat is applied in particular areas of probe head 12. Heater 52 can be varied based on heating needs of probe head 12. Because a high temperature co-fired ceramic process is used to form probe head 12, heater 52 can be positioned in locations that are traditionally difficult to place heaters. For example, a portion of heater 54 can be placed closer to tip 24 than is possible with brazing. Tip 24 is an area of probe head 12 that is prone to accreting ice and is traditionally difficult to heat. Aluminum nitride ceramic body 52 also has a high thermal conductivity and heats or cools quickly for increased efficiency and a fast response time. Heater 52 can be pulsed to save power in certain conditions. Heater 52 is tailored to provide heat only where heat is needed, decreasing power needs of probe head 12, reducing overheat events, and resulting in more effective and cost-efficient heating of probe head 12.
Because probe head 12 has about zero porosity, there is no joint between ceramic body 52 and heater 54. As a result, heater 54 is better protected, reducing corrosion and oxidation. Additionally, stresses between the insulator, or substrate, and the conductor during thermal cycling are low such that probe head 12 is stronger and has increased reliability. Exterior surface 26 and interior surface 28 are also better protected. Ceramic body 52 is a hard substrate, which reduces erosion effects on lead edges.
Probe head 100 has the same structure and function as probe head 10 described with respect to
In this embodiment, probe head 100 has heater 118 embedded within ceramic body 116. Ceramic body 116 and heater 118 have a similar structure and function as ceramic body 52 and heater 54, respectively, described with respect to
Ceramic layers 120 and 122 and heater layer 124 undergo a high temperature co-fired ceramic process to form probe head 100. Ceramic layers 120 and 122 of ceramic body 116 form the structure of probe head 12 and provide insulation for heater layer 124 of heater 118. Variation of location within probe head 100 and thickness of heater layer 124 allow for tailored heat distribution along probe head 100.
Probe head 200 has the same structure and function as probe head 10 described with respect to
In this embodiment, probe head 200 has heater 218 embedded within ceramic body 216. Ceramic body 216 and heater 218 have a similar structure and function as ceramic body 52 and heater 54, respectively, described with respect to
In
Ceramic layers 222, 224, and 226 and heater layers 228 and 230 undergo a high temperature co-fired ceramic process to form probe head 200. Ceramic layers 222, 224, and 226 of ceramic body 216 form the structure of probe head 200. Ceramic layers 222 and 224 provide insulation for heater layer 228 of heater 218, and ceramic layers 224 and 226 provide insulation for heater layer 230 of heater 218. Variation of location within probe head 200 and thickness of heater layers 228 and 230 allow for tailored heat distribution along probe head 200. Having multiple heater layers 228 and 230 allows for increased Watt density and enables further tailoring of heat distribution. Increased Watt density results in increased heat in regions of probe head 200 more likely to accrete ice, such as tip 24. As shown in
Probe head 300 has the same structure and function as probe head 10 described with respect to
In this embodiment, probe head 300 has heater 318 and temperature sensor 320 embedded within ceramic body 316. Ceramic body 316 and heater 318 have a similar structure and function as ceramic body 52 and heater 54, respectively, described with respect to
Ceramic layers 322, 324, and 326, heater layer 328, and sensor layer 330 undergo a high temperature co-fired ceramic process to form probe head 300. Ceramic layers 322, 324, and 326 of ceramic body 316 form the structure of probe head 300. Ceramic layers 322 and 324 provide insulation for sensor layer 330 of temperature sensor 320, and ceramic layers 324 and 326 provide insulation for heater layer 328 of heater 318. Variation of location within probe head 300 and thickness of heater layer 328 allow for tailored heat distribution along probe head 300. Temperature sensor 320 allows for temperature measurement at specific locations within probe head 300, allowing for health monitoring and prognostics, and simplifies installation.
Probe head 400 has a similar structure and function as probe head 10 described with respect to
First water dam 418 is semi-annular and has a first end connected to interior surface 412 and a second end within passageway 416. Second water dam 420 is annular and has a periphery connected to interior surface 412 along an entire circumference of second water dam 420. Second water dam 420 has bore 422, which is a passageway extending from an upstream end to a downstream end of second water dam 420. Bore 422 is in alignment with first water dam 418. Second water dam 420 is downstream of first water dam 418. First water dam 418 and second water dam 420 are made of the same material as the ceramic body (described with respect to
Drain hole 424 is a hole that extends from interior surface 412 to exterior surface 410 of probe head 400. Drain hole 424 is downstream of first water dam 418 and upstream of second water damn 420 such that drain hole 424 is between first water dam 418 and second water dam 420. In this embodiment, probe head 400 has one drain hole 424. In alternate embodiments, probe head 400 may have any number of drain holes 424. First water dam 418, second water dam 420, and drain hole 424 act as a water management feature of probe head 400.
As external airflow enters probe head 400 and flows through passageway 416, water and ice particles in the airflow hit and are knocked down by first water dam 418 and second water dam 420 as airflow changes direction in response to first water dam 418 and second water dam 420. Because probe head 400 is heated, first water dam 418 and second water dam 420 are heated, and knocked down ice particles melt within passageway 416. Second water dam 420 prevents the water from moving further downstream within probe head 400. Water then drains out of passageway 416 via drain hole 424 to exit probe head 400. Therefore, first water dam 418 and second water dam 420 prevent ingested airflow and contaminants within the airflow from having a straight path through probe head 400 and affecting the functionality of probe head 400.
Probe head 500 has a similar structure and function as probe head 10 described with respect to
First water dam 516 has a first end connected to interior surface 512 and a second end within passageway 514. Second water dam 518 has a first end connected to interior surface 512 opposite the first end of first water dam 516 and a second end within passageway 514. First water dam 516 and second water dam 518 radially overlap. Second water dam 518 is downstream of first water dam 516. First water dam 516 and second water dam 518 are made of the same material as the ceramic body (described with respect to
Drain hole 520 is a hole that extends from interior surface 512 to exterior surface 510 of probe head 500. Drain hole 520 is downstream of first water dam 516 and second water damn 518. In this embodiment, probe head 500 has one drain hole 520. In alternate embodiments, probe head 500 may have any number of drain holes 520. First water dam 516, second water dam 518, and drain hole 520 act as a water management feature of probe head 500.
As external airflow enters probe head 500 and flows through passageway 514, water and ice particles in the airflow hit and are knocked down by first water dam 516 and second water dam 518 as airflow changes direction in response to first water dam 516 and second water dam 518. Because probe head 500 is heated, first water dam 516 and second water dam 518 are heated, and knocked down ice particles melt within passageway 514. Water then drains out of passageway 514 via drain hole 520 to exit probe head 500. Therefore, first water dam 516 and second water dam 518 prevent ingested airflow and contaminants within the airflow from having a straight path through probe head 500 and affecting the functionality of probe head 500.
Discussion of Possible EmbodimentsThe following are non-exclusive descriptions of possible embodiments of the present invention.
A probe head for an air data probe includes a ceramic body; and a heater embedded within the ceramic body.
The probe head of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
The probe head is formed by a high temperature co-fired ceramic process.
The probe head has about zero porosity.
The ceramic body makes up an exterior surface of the probe head and an interior surface of the probe head.
The ceramic body is aluminum nitride.
The heater is tungsten composite.
The heater varies in thickness.
A temperature sensor embedded within the ceramic body.
A passageway formed by an interior surface of the probe head and extending an entire length of the probe head; a post having a first end connected to the interior surface of the probe head and a second end connected to the interior surface of the probe head such that the post extends through a center of the passageway; and a drain hole extending from the interior surface of the probe head to an exterior surface of the probe head.
The interior surface of the ceramic body forms a lip such that the passageway has a smaller cross-sectional area at the lip.
The heater comprises a first heater layer.
The ceramic body comprises a first ceramic layer and a second ceramic layer, the first heater layer being between the first ceramic layer and the second ceramic layer.
The heater further comprises a second heater layer between the second ceramic layer and a third ceramic layer of the ceramic body.
A via contacting the first heater layer and the second heater layer.
A temperature sensor having a sensor layer between the second ceramic layer and a third ceramic layer of the ceramic body.
An air data probe comprising: the probe head of the preceding paragraph; and a transition piece having a first end connected to the probe head and a second end configured to be connected to a strut such that the transition piece connects the probe head to the strut.
The probe head includes a shoulder, and the first end of the transition piece is connected to the probe head at the shoulder.
The shoulder has a metalized surface, and the transition piece is made of nickel.
The transition piece is a high stress area of the air data probe.
A passageway formed by an interior surface of the probe head and extending an entire length of the probe head; a first water dam having a first end connected to the interior surface of the probe head and a second end within the passageway; a second annular water dam having a periphery connected to the interior surface of the probe head along an entire circumference of the second water dam, the second water dam including a bore extending from an upstream end to a downstream end of the second water dam; and a drain hole extending from the interior surface of the probe head to an exterior surface of the probe head between the first water dam and the second water dam.
A passageway formed by an interior surface of the probe head and extending an entire length of the probe head; a first water dam having a first end connected to the interior surface of the probe head and a second end within the passageway; a second water dam having a first end connected to the interior surface of the probe head opposite the first end of the first water dam and a second end within the passageway; and a drain hole extending from the interior surface of the probe head to an exterior surface of the probe head downstream of first water dam.
An air data probe includes a strut; a probe head connected to the strut, the probe head comprising: a ceramic body; and a heater embedded within the ceramic body; and a transition piece having a first end connected to the probe head and a second end connected to the strut such that the transition piece connects the probe head to the strut.
While the invention has been described with reference to an exemplary embodiment(s), 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 invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims
1. A method of forming a probe head for an air data probe, the method comprising:
- applying a heater to a ceramic body; and
- co-firing the heater and the ceramic body to form the probe head of the air data probe such that the heater is embedded within the ceramic body.
2. The method of claim 1, wherein the probe head is formed by a high temperature co-fired ceramic process.
3. The method of claim 1, wherein the probe head is co-fired such that the probe head has about zero porosity.
4. The method of claim 1, wherein the heater and the ceramic body form a fully dense material.
5. The method of claim 1, wherein the ceramic body makes up an exterior surface of the probe head and an interior surface of the probe head.
6. The method of claim 1, wherein the ceramic body is aluminum nitride.
7. The method of claim 1, wherein the heater is tungsten composite.
8. The method of claim 1, wherein the heater varies in thickness.
9. The method of claim 1, wherein the heater is applied to the ceramic body to form layers of the heater within the ceramic body of the probe head.
10. The method of claim 1, further comprising applying a temperature sensor to the ceramic body, wherein co-firing the heater and the ceramic body includes co-firing the temperature sensor such that the temperature sensor is embedded within the ceramic body.
11. The method of claim 1, further comprising:
- forming a passageway via an interior surface of the probe head that extends an entire length of the probe head; and
- connecting a first end of a post to the interior surface of the probe head and a second end of the post to the interior surface of the probe head such that the post extends through a center of the passageway, wherein a drain hole extends from the interior surface of the probe head to an exterior surface of the probe head.
12. The method of claim 11, wherein the post is connected to the interior surface of the probe head via brazing or gluing.
13. The method of claim 11, wherein the interior surface of the ceramic body forms a lip such that the passageway has a smaller cross-sectional area at the lip.
14. The method of claim 1, wherein the heater is applied to the ceramic body such that the heater is tailored within the probe head to provide heat to an area of the probe head prone to accreting ice.
15. The method of claim 1, further comprising:
- connecting a first end of a transition piece to the probe head, wherein a second end of the transition piece is configured to be connected to a strut such that the transition piece connects the probe head to the strut.
16. The method of claim 15, wherein the probe head includes a shoulder, and the first end of the transition piece is connected to the probe head at the shoulder.
17. The method of claim 15, further comprising applying a metalized surface to the shoulder, and wherein the transition piece is made of nickel.
18. The probe head of claim 1, further comprising:
- forming a passageway via an interior surface of the probe head that extends an entire length of the probe head;
- connecting a first end of a first water dam to the interior surface of the probe head, wherein a second end of the first water dam is within the passageway; and
- connecting a periphery of a second annular water dam to the interior surface of the probe head along an entire circumference of the second water dam, the second water dam including a bore extending from an upstream end to a downstream end of the second water dam;
- wherein a drain hole extends from the interior surface of the probe head to an exterior surface of the probe head between the first water dam and the second water dam.
19. The method of claim 1, further comprising:
- forming a passageway via an interior surface of the probe head that extends an entire length of the probe head;
- connecting a first end of a first water dam to the interior surface of the probe head, wherein a second end of the first water dam is within the passageway; and
- connecting a first end of a second water dam to the interior surface of the probe head opposite the first end of the first water dam, wherein a second end of the second water dam is within the passageway;
- wherein a drain hole extends from the interior surface of the probe head to an exterior surface of the probe head downstream of first water dam.
20. The method of claim 1, wherein the heater is applied to the ceramic body as traces of the heater being applied to the ceramic body as an unrolled tape, and the heater and the ceramic body are wound around a mandrel prior to being co-fired.
Type: Application
Filed: Jan 31, 2022
Publication Date: May 19, 2022
Inventors: Christopher Sanden (Bloomington, MN), Scott D. Isebrand (Minneapolis, MN), Greg Allen Seidel (Lakeville, MN)
Application Number: 17/589,332