U.S. patent application number 10/387625 was filed with the patent office on 2004-09-16 for total air temperature probe providing a secondary sensor measurement chamber.
Invention is credited to Ice, Paul A..
Application Number | 20040177683 10/387625 |
Document ID | / |
Family ID | 32771612 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040177683 |
Kind Code |
A1 |
Ice, Paul A. |
September 16, 2004 |
Total air temperature probe providing a secondary sensor
measurement chamber
Abstract
A total air temperature sensor probe samples the air stream
surrounding an aircraft in flight, and includes a duct carrying a
fluid flow a portion of which is diverted to a primary chamber
mounting a total air temperature sensor. A secondary chamber has a
secondary sensor for sensing a different property of a sampled air
stream. The secondary chamber is open to receive air flow from
passageways in the total air temperature probe.
Inventors: |
Ice, Paul A.; (Apple Valley,
MN) |
Correspondence
Address: |
John Veldhuis-Kroeze
WESTMAN CHAMPLIN & KELLY
Suite 1600 - International Centre
900 South Second Avenue
Minneapolis
MN
55402-3319
US
|
Family ID: |
32771612 |
Appl. No.: |
10/387625 |
Filed: |
March 13, 2003 |
Current U.S.
Class: |
73/170.02 ;
374/E13.006 |
Current CPC
Class: |
G01K 13/028 20130101;
G01K 13/02 20130101 |
Class at
Publication: |
073/170.02 |
International
Class: |
G01W 001/00; G01P
013/00 |
Claims
What is claimed is:
1. An air data sensor probe for sensing parameters of air flowing
past the probe, comprising: an outer housing; a primary air flow
passage through the housing; a primary chamber in the housing
receiving air flow from the primary air flow passage; a temperature
sensor in the primary chamber; a secondary passage in the housing;
a secondary chamber in the housing receiving air from the secondary
passage; a secondary air data sensor in the secondary chamber, the
secondary data sensor sensing a parameter of air in the secondary
chamber.
2. The air data sensor probe of claim 1 wherein the secondary
passage comprises openings leading from the primary air flow
passage.
3. The air data sensor probe of claim 1 wherein the secondary
passage comprises a laterally extending air exit passage.
4. The air data sensor of claim 1, wherein the secondary chamber
includes openings to the primary chamber.
5. The air data sensor probe of claim 1 wherein the secondary air
data sensor is selected from the group consisting of a humidity
sensor, a pressure sensor, a water vapor sensor, a CO.sub.2 sensor,
a nitrogen sensor, an air constituent sensor, and an air
contaminant sensor.
6. The air data sensor probe of claim 1 wherein the secondary
chamber is positioned in the housing forward of the primary
chamber, and further comprising a port leading to the secondary
chamber from the secondary passage in the housing.
7. The air data sensor probe of claim 6 and further comprising an
aspirator tube in the secondary chamber to eject air to reduce
pressure in the secondary chamber.
8. The air data sensor probe of claim 1 wherein the secondary
chamber is positioned in the housing aft of the primary chamber,
and wherein ports from the primary chamber lead directly to the
secondary chamber.
9. The air data sensor probe of claim 8 and further comprising an
aspirator tube in the secondary chamber to eject air to reduce
pressure in the secondary chamber.
10. The air data sensor probe of claim 9 wherein the aspirator tube
in the secondary chamber comprises a combined sensor chamber and
aspirator tube, the aspirator tube being separated from the sensor
chamber, and rearwardly facing ports for discharging air from the
aspirator tube.
11. The air data sensor probe of claim 9 wherein a low pressure
source of air is connected to the aspirator tube.
12. The air data sensor probe of claim 8 wherein the secondary
chamber has openings on an aft side thereof for discharging air
from the primary and secondary chambers.
13. An air data sensor probe for sensing parameters of air flowing
past the probe, comprising: a housing having a base configured to
be supported on an aircraft skin; an inlet scoop in the housing at
a leading end to receive air flow; an exit channel in the housing
at a trailing end from which air flow exits; an interior air flow
duct in the housing between the inlet scoop and the exit channel; a
primary chamber in the housing connected to and receiving air flow
from the interior air flow duct; a primary sensor positioned in the
primary chamber for measuring a total air temperature; a secondary
chamber in the housing; and a secondary air data sensor positioned
in the secondary chamber for measuring a secondary air data
parameter.
14. The air data sensor probe of claim 13 wherein the secondary
chamber is positioned in the housing forward of the primary
chamber.
15. The air data sensor probe of claim 14 and further comprising a
secondary passage in the housing, the secondary passage providing
air to the secondary chamber.
16. The air data sensor probe of claim 15 wherein the secondary
passage includes openings leading from the interior air flow duct
to receive air flow from the interior air flow duct.
17. The air data sensor probe of claim 15 wherein the secondary
passage comprises a laterally extending air exit passage.
18. The air data sensor probe of claim 13 wherein the secondary
chamber includes openings to the primary chamber.
19. The air data sensor probe of claim 13 wherein the secondary air
data sensor is selected from the group consisting of a humidity
sensor, a pressure sensor, a water vapor sensor, a CO.sub.2 sensor,
a nitrogen sensor, an air constituent sensor, and an air
contaminant sensor.
20. The air data sensor probe of claim 13 wherein the secondary
chamber is positioned in the housing aft of the primary
chamber.
21. The air data sensor probe of claim 20 wherein ports from the
primary chamber lead directly to the secondary chamber.
22. The air data sensor probe of claim 21 and further comprising an
aspirator tube in the secondary chamber to eject air to reduce
pressure in the secondary chamber.
23. The air data sensor probe of claim 22 wherein the aspirator
tube in the secondary chamber comprises a combined sensor chamber
and aspirator tube, the aspirator tube being separated from the
sensor chamber, and rearwardly facing ports for discharging air
from the aspirator tube.
24. The air data sensor probe of claim 22 wherein a low pressure
source of air is connected to the aspirator tube.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a total air temperature
sensor probe carrying a total air temperature sensor in a primary
chamber, and having a second chamber in which an additional or
secondary sensor is mounted. The secondary sensor is used for
measuring additional properties or constituents of air.
[0002] Having a second sensor in a probe presents challenges in
accommodating the operational needs of such sensor or probe.
Impingement of liquid water droplets in the air flow can
electrically short out some types of sensors, and if the sensor
projects directly into the airstream, airborne debris can
mechanically damage or contaminate the sensor. The sensors may
require certain geometric features such as alignment of parts or
specific transmission distances, particularly when using
optical-based sensors.
[0003] A total air temperature probe housing must be constructed in
a manner to maintain the integrity of the primary measurement,
namely total air temperature. Inclusion of a secondary sensor can
potentially interfere with the air flow past the total air
temperature sensor, and thus reduce the integrity of the total air
temperature measurement.
SUMMARY OF THE INVENTION
[0004] The present invention relates to a total air temperature
sensor probe that has a total air temperature sensor mounted in a
primary chamber or passageway and which has a separate interior or
secondary chamber. Both chambers are protected from debris and
impingement of water droplets. The separate interior chamber has a
separate, second or secondary sensor therein. The secondary sensor
is designed to obtain a measurement of a selected air data
parameter (other then total air temperature), in order to determine
properties of the sampled air stream, or of the air mass in which
the probe is immersed.
[0005] The secondary chamber is formed within the probe housing,
and is open to passageways that provide an air flow into the
secondary chamber, and across the secondary sensor, without
disrupting the primary air flow across the total temperature sensor
in the primary chamber. Also, the secondary chamber has an air flow
inlet positioned so as to limit or avoid introduction of water
droplets, ice crystals and airborne particles and debris into the
secondary chamber.
[0006] In one embodiment of the invention, the secondary chamber is
positioned in the probe housing forwardly (on the upstream side) of
the total air temperature sensor primary flow passage. The inlet
port to the secondary chamber is connected to a laterally extending
channel containing air drawn from the bulk air mass surrounding the
probe. The laterally extending channel can also be connected to
bleed holes used to bleed off boundary layer air from the primary
flow scoop. Thus, the air within the laterally extending channel
can also include bleed air in some embodiments. Due to the
construction of the secondary chamber, and particularly its
connection to the relatively protected laterally extending channel,
air admitted into the secondary chamber does not contain directly
impinging water droplets, particles, and the like. If desired, both
a forward secondary chamber and an aft secondary chamber can be
involved, each housing a corresponding secondary sensor.
[0007] Alternatively, a chamber aft (or on the downstream side) of
the main total air temperature sensor primary flow passage can be
provided in configurations illustrated herein, for mounting a
secondary sensor. Suitable ports duct air across the secondary
sensor, and keep it shielded from particles and debris.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a sectional view of a total air temperature sensor
probe having a secondary chamber for mounting a sensor and made
according to an embodiment of the present invention;
[0009] FIG. 2 is a sectional view of an alternate form of a total
air temperature sensor probe having the secondary chamber aft of
the main sensing element;
[0010] FIG. 3 is a cut-away view of a perforated tube for mounting
a secondary sensor in an aft chamber of the total air temperature
probe housing of FIG. 2;
[0011] FIG. 4 is a sectional view showing an aft secondary sensor
chamber with an aspirated-type total air temperature sensor;
[0012] FIG. 5 is a perspective view of a modified dual air passage
aspirator tube and sensor housing for use in an aft probe chamber;
and
[0013] FIG. 6 is a sectional view taken on line 6-6 in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] A total air temperature (sometimes called a TAT) sensor
probe 10 includes an outer probe housing 12 that is suitably formed
to have a streamlined, generally airfoil cross sectional shape. The
housing 12 has a base 11 supported on an aircraft skin 13. The
housing 12 further includes an interior air flow duct 14 (the
primary air flow passage) that has an inlet scoop 16 at a leading
(or upstream) end to receive air flowing in the direction indicated
by arrows 15. An exit channel 18 is provided at the downstream (or
trailing) end of the housing. In some embodiments, a constriction
or venturi portion 20 is also formed in mid portions of duct 14.
However, other embodiments of the air data sensor probes of the
invention do not include constriction or venturi portion 20.
[0015] The duct 14 has a flow separation bend 22 that diverts a
portion of the air flow between the inlet scoop 16 and the exit
channel 18 and causes the diverted air to flow through a port or
aperture 24 into a TAT sensor flow passage or primary chamber 26. A
temperature sensor assembly 28 is positioned in the flow passage
26. The temperature sensor assembly includes a sensing element 30,
and has a radiation shield 32 around the sensing element. Sensing
element 30 senses the temperature of the air that is flowing around
the sensor in the passage 26, and then the air in passage 26 exits
through ports 34, into an aft chamber 36, and out exit ports 38 and
38A in the wall defining the aft chamber 36.
[0016] The flow separation bend 22 is formed in part by an inner
elbow or bend curved wall 40, that has a number of boundary layer
control bleed holes 42 extending therethrough. The bleed holes 42
lead to a laterally extending air exit passageway 44 (secondary
passage). The arrows in the bleed holes 42 in FIG. 1 show that the
air that forms a boundary layer around the elbow or bend curve wall
40 bleeds or flows into the passageway 44 and then flows laterally
to exit from the passageway 44 at side exit ports (not shown in the
sectional view of FIG. 1) at the ends of passageway 44.
[0017] TAT sensor flow passage 26 is formed by a surrounding wall
46, to separate passage 26 from a forward secondary chamber 48
formed in the probe housing 12. The chamber 48 is used for mounting
a secondary air data sensor 50. For example, secondary air data
sensor 50 can be a humidity sensor, such as an optical or other
type of humidity sensor, and can be used in a conventional manner.
In other embodiments, secondary air data sensor 50 can be other
types of sensors, such as a water vapor sensor, a CO.sub.2 sensor,
a nitrogen sensor, a pressure sensor, an air constituent sensor, or
an air contaminant sensor, to name a few.
[0018] Air flow from the laterally extending passageway 44 is
admitted into the forward secondary chamber 48 through a flow port
52 placed in the bottom wall forming the laterally extending air
passageway 44. Air flowing from passageway 44, through the port 52,
and into the secondary chamber 48 is essentially at static
pressure. Such air can include air drawn from the bulk air mass
surrounding probe 10 which enters passageway 44 at its ends, as
well as boundary layer bleed air withdrawn from the primary flow
duct via bleed holes 42. Air flowing through the flow port 52 and
into the secondary chamber 48 flows across the secondary sensor 50.
Air from secondary chamber 48 then exits the secondary chamber
through ports 54 connected to passage 26, and through the ports 34
into the aft chamber 36. This air then exits probe 10 through the
exit ports 38 and 38A.
[0019] Depending on the parameter being measured, the secondary
sensor 50 does not require a dynamic flow of air (i.e. air flow
from the free stream entering probe 10 at inlet scoop 16) in the
same nature as the TAT measurement requires. In other words, the
parameter sensed in the secondary chamber may be sensed from air at
essentially static pressure provided by laterally extending
passageway 44 from the bulk air mass surrounding probe 10.
Therefore, the air supplied to the secondary sensor 50 may not need
to be taken directly from the primary duct (interior air flow duct
14). For sensing parameters such as humidity, static pressure, and
air constituents/contaminants, it is necessary only to admit air
into the secondary chamber from the surrounding air mass in which
the probe is immersed, in a protected manner. Air entering
laterally extending passageway 44 from either bleed holes 42 or
from side exit ports of passageway 44 satisfy this need. While the
chamber within which the secondary sensor 50 is located must have
some volumetric turnover, the properties being measured are more
like bulk properties of the air mass.
[0020] The channel 48 and port 52 provide a relatively protected
area for the secondary sensor 50 from impinging particles, water,
etc. This protection is afforded mostly by the overall geometry of
the probe since this chamber resides forward of the wall 46 of
sensor flow passage 26 and under inner elbow 40 of air flow duct
14. Air that flows through port 52 from passageway 44 is relatively
free of particles that would be of a size sufficient to cause
damage to the secondary sensor 50. This is due to the fact that
larger particles entering air flow duct 14 will have sufficient
kinetic energy to pass through probe 10 at exit channel 18. It is
also due to the fact that larger particles will have too much
kinetic energy to enter laterally extending passageway 44 from the
side exit ports, travel laterally through passageway 44 and down
through port 52. Thus, the air flow through the secondary chamber
48 is essentially free of damaging particles, such as ice and the
like.
[0021] Because the air in chamber 48 is substantially free of
damaging particles, fewer design restrictions can be placed on the
types of sensors used as secondary air data sensor 50. For example,
impingement of liquid water droplets can electrically short certain
types of sensors. Also, airborne debris can mechanically damage or
contaminate certain types of sensors, such as optical sensors. With
embodiments of the invention, these designed restrictions are
minimized, allowing particular sensor types of sensor 50 to be
selected based on other criteria such as cost or performance.
[0022] The air flow through secondary chamber 48 can be controlled
by controlling the size of the inlet port 52 so that it will be
adequate to flow over the sensor 50. The air then flows out the
passageways or ports 54, 34, 38, and 38A. Adequate control of the
air flow in the secondary chamber 48, and avoiding particles in
such air flow, enables sensors to operate correctly and thus
accurate sensing is achieved.
[0023] While secondary air data sensor 50 is shown in forward
secondary chamber 48, in other embodiments the secondary sensor can
instead be located in aft chamber 36. Also, two separate secondary
sensors can be included, one in each of chambers 48 and 36. This is
described in greater detail with reference to FIGS. 2-6.
[0024] FIG. 2 illustrates an alternate form of a TAT probe 69. In
this form of the invention, probe 69 has a probe housing 70 that
protrudes from base 102 supported on an aircraft skin 73 and has an
elongated upper air flow tube 72 defining an air flow passageway or
duct 74, with an inlet end air scoop 76. The air flow direction is
indicated by arrow 71. The boundary layer control in this form of
the invention is provided by bleed openings 78 through the wall of
tube 72 along the duct 74. The duct 74 has a reduced-size control
orifice 80 at the trailing end of the duct 74.
[0025] A TAT sensor inlet flow port 82 is provided, and leads to a
TAT flow passage or primary chamber 84 in which a TAT sensor 86 is
mounted. The sensor passage 84 has lower air outlet ports 89, as
shown in the surrounding wall 112 of the passage 84. An elbow wall
portion 90 is positioned in the flow duct 74. The elbow wall
portion is raised from the bottom of the duct 74 and has small
bleed air openings 87 extending there through so bleed air enters
secondary chamber 106.
[0026] In this form of the invention, an aft or secondary chamber
96 is provided at the aft portion of the probe housing 70. An air
outlet opening or port 98 leads from the chamber 96 to the exterior
of the probe 69. Within the aft chamber 96 is mounted a secondary
air data sensor 100, in a suitable manner, to the base 102 of the
probe housing 70. This secondary sensor receives air flow from the
ports 89, as air passes from primary chamber 84 through ports 89 to
secondary chamber 90, and flows out through the outlet port 98 on
the aft side of the probe housing 70.
[0027] The probe housing 70 also has a forward secondary chamber
106, which can also (or alternatively) be used for mounting a
secondary sensor 108 (represented in dotted lines) if desired, by
providing a port 109 between the laterally extending flow channel
88 and secondary chamber 106. Ports 111 are placed in surrounding
wall 112 of TAT flow passage 84. Air flows from secondary chamber
106 through ports 111 and 89, and through port 98. The probe can
thus have a single secondary chamber (such as chamber 48 in FIG. 1,
or chambers 96 or 106 in FIG. 2) and corresponding secondary
sensor, or the probe can have a pair of secondary chambers (i.e.,
chambers 96 and 106) and corresponding secondary sensors in
addition to the primary chamber 84 for the TAT sensor.
[0028] FIG. 3 illustrates a cut away section of the probe housing
70 in accordance with one possible modification of TAT probe 69
shown in FIG. 2. In embodiments of the present invention utilizing
an aft secondary sensor chamber, such as chamber 96 in FIG. 2,
attention should be given to the size, mounting, and location of
the secondary sensor 100, such that the air flow affecting
characteristics of the primary TAT sensor 86 are preserved. For
example, in one possible modification of TAT probe 69 shown in FIG.
2, a perforated tube 110 (FIG. 3) surrounds, and is closely spaced
from, a secondary air data sensor 100 in order to support the
secondary sensor while allowing air to flow to the secondary
sensor. Tube 110 is shown with portions cut away in order to
illustrate the positioning of secondary sensor 100 within tube
110.
[0029] While a single circular perforation 111 is shown in tube
110, additional perforations can be included, other perforation
shapes can be utilized, or other techniques can be used to allow
air to flow to sensor 100. In these embodiments, perforated tube
110 is mounted onto the base 102 of the probe housing 70,
projecting upwardly into aft secondary chamber 96. Since use of
perforated tube 110 shown in FIG. 3 is only one possible technique
for mounting the secondary sensor 100 within the aft secondary
chamber while maintaining the air flow properties of the primary
TAT sensor, tube 110 is not shown in FIG. 2. Other techniques can
be used with the TAT probe configuration shown in FIG. 2 as
well.
[0030] FIG. 4 shows a modified TAT sensor probe, constructed
essentially the same as the probe of FIG. 1. The same basic
numerals will be used in FIG. 4. The probe 10 has an aspirator tube
122 in the aft chamber 36 for aspirating or ejecting air from the
interior passageways and chambers of the probe housing 12 to aid in
cooling the probe and maintaining an air flow across the TAT
sensing element 30 and across a secondary sensor 124 so the air
flow is representative of the outside air conditions. The
construction of the TAT sensor housing 12 is the same as that shown
in FIG. 1, except that an aft secondary air data chamber 120 is
provided for, and contains the aspirator tube 122 as well as the
secondary sensor 124.
[0031] Sensor 124 can be an optical sensor for sensing an air data
parameter, such as humidity, or can be other types of sensors. For
example, sensor 124 can be any of the sensor types mentioned in
reference to FIG. 1, but is not limited to these sensor types. In
the embodiment illustrated in FIG. 4, secondary sensor 124 is
positioned adjacent aspirator tube 122. However, as is described
below in greater detail with reference to FIGS. 5 and 6, aspirator
tube 122 and secondary sensor 124 can be combined if desired.
[0032] The aspirator tube 122 is connected to a tube 126 that
extends into the interior of the aircraft. Tube 122 has a fitting
128 that leads to a low pressure, flow controlled pressure source
129 in the aircraft. The pressure source 129 can be a fan or pump,
and is designed to provide an adequate air flow for the aspiration
of chamber 120. The aspirator tube 122 has a number of rearwardly
facing or aft facing ports 130, to provide aspiration in a known
manner used with TAT sensors in the prior art. The flow out of the
ports 130 and exit port 38 reduces the pressure in chamber 120,
thereby increasing the air flow through TAT sensor flow passage 26
and across sensing element 30, and if used, the forward and/or
rearward secondary chambers 48 and 120. Each exit port 38 can be
aligned with one of the ports 130, to permit the aspiration air
flow to be ejected. The flow through or across the secondary sensor
124 is air which flows through the chamber 120 as previously
described in connection with FIG. 2.
[0033] A modified aspirator tube and secondary sensor housing or
shield is shown in FIGS. 5 and 6. These modifications can be used,
for example, in alternate embodiments of the TAT sensor probe 10
shown in FIGS. 1 and 4. In these embodiments, a combination
aspirator tube and sensor housing tube 131 is attached to the base
11 of the TAT probe housing 12 and connected to tube 126 and
pressure source 129 in a manner shown in FIG. 4. Tube 131 provides
an interior chamber 134 for mounting a secondary sensor 136 in
place. A second interior chamber 135 is also provided by tube 131.
The tube 131 has laterally facing ports 138 to provide for air flow
past secondary sensor 136. Air flow past sensor 136 also enters
tube 131 from its open top 132. The sensor 136 is subjected to the
air that is flowing through the TAT probe and can be used for
sensing humidity or some other parameter of the air.
[0034] Additional ports 144 in tube 131 are included to enable
aspiration air flow in chamber 135 of tube 131. While the position
of secondary sensor 136 within chamber 120 protects it from
impaction by particles, its position within tube 131 provides
additional protection, while reducing the design considerations
required to include both a secondary sensor and an aspirator
tube.
[0035] The aspirator tube section of FIG. 6 is formed with a pair
of tapered walls 140A and 140B that join the side walls of the tube
131, and are formed in a V-shape that forms an aspirator air
passageway 135. A series of rear facing discharge ports 144 are
provided at the rearwardly extending peak 146 of the aspirator tube
formed by walls 140A and 140B, to provide for ejection of air from
the passageway 135, and from the interior of the probe housing, as
shown in FIG. 4. The passageway 135 is connected to carry flow from
the low pressure source 129.
[0036] Thus, the arrangement shown in FIGS. 5 and 6 provides a dual
compartment tube in the aft chamber for an aspirated TAT sensor
probe, to combine the functions of the aspirator tube and a shield
for secondary sensor 136 in one upright structure. The shape of
combined sensor and aspirator tube 131 is streamlined to preclude
undue obstruction of air exiting primary TAT flow passage 26,
enabling proper TAT sensing function and aspirator operation. The
secondary sensor can be used for sensing humidity, or any other
aspect or component of air.
[0037] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention. For example,
while the present invention is described with reference to certain
secondary sensor types (e.g. humidity sensors, etc.), any type of
secondary sensor which measures an aspect, property or component of
air can be used.
* * * * *