CA1272795A - Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique - Google Patents
Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo techniqueInfo
- Publication number
- CA1272795A CA1272795A CA000511245A CA511245A CA1272795A CA 1272795 A CA1272795 A CA 1272795A CA 000511245 A CA000511245 A CA 000511245A CA 511245 A CA511245 A CA 511245A CA 1272795 A CA1272795 A CA 1272795A
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- Canada
- Prior art keywords
- ice
- pulse
- transducing means
- ultra
- transducer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
METHOD AND APPARATUS FOR MEASUREMENT OF ICE THICKNESS
EMPLOYING ULTRA-SONIC PULSE ECHO
TECHNIQUE
Abstract of the Disclosure Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique, wherein an ultra-sonic pulse is emitted from a transducer at the ice-accreting surface of a structure, the pulse is reflected at the periphery of the accreted ice and the reflection is detected. The time delay is calibrated and related to ice thickness and accretion rate.
EMPLOYING ULTRA-SONIC PULSE ECHO
TECHNIQUE
Abstract of the Disclosure Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique, wherein an ultra-sonic pulse is emitted from a transducer at the ice-accreting surface of a structure, the pulse is reflected at the periphery of the accreted ice and the reflection is detected. The time delay is calibrated and related to ice thickness and accretion rate.
Description
t78~3t,~
1 ~ of the Invention The present in~ention relates to ic~-prevention sy~tems for aircraft struc~ures, and more pa~ticularly, to an apparatus for measurement of ice thickness employing ultra sonic pulse echa techniques.
The problems relating to the formation of ice on aircrat s~ructures are well known. In certain cli~atic condi-tions water droplets ~ay exist at subfreezing temperatures in a liquid state. These supercooled droplet~ nucleate and ~orm ice upon contact with the aircra~t surface~. Ice the~efore tends to form on the leading edges of aircraft s~ructures. The ice can degrade aircraft performance through increasing the effec-ti~e weight o~ the aircraft and by increasing drag re~istance and reducing lift provided by~the airfolls.
lS Various ice detection devices are well known. In one known detection device, a probe is provided which extends beyond the surface to be monitored. ~owe~er, the manner of ice accretion on such prabe is different from the manner of ice accretion on the ~urface to be monitored. Hence, the accretion rate on the probe will be higher than the accretion rate on the ~ur~ace to be monitored.
In another known device, the ice thickness is mea~ured by the changing capacitance o~ a surface capacitor due to the dielectric properties of the ice which has accreted on the probe. One problem with ~hi3 latter class of devices is ~;Y~
P~
,~ tj~3 ;~
1 that in o~der to accu~htely interpret the data received from the probe, the type oE ice (rime, glaze, or mixed) must be known to the user~
It is there~ore an object of the present invention to provide an apparatus ~or measurement of ice thic~ness which can be mounted flush with the surface upon which ice accretion thic~ness is to be measured~
It is another object of the present invention provide an apparatu3 for measurement of ice thic~ness which i~
insensitive to types of ice accreted. .
It i~ yet another object of the present in~ention to .
provide an apparatus or meas~rement of ice thic~ne-~ which is .
flush with the surface upon which ice acc~etion thic~ne~ is to be measured and can also measure the rate of ice accretion.
lS It i~ a further object of the present invention to pro~ide an apparatus for measurement of-ice thic~ness employing : .
ultra-sonic pulse echo techniques to measure ice accretion .
thickne~s and al90 the rate at which :ice is accre~ed. .
-Summary of the Invention The present invention relates to an apparatus for .
: measurement o~ the thickness of accreted ice and rate of .
accretion employing an ultra-so~ic pulse e~ho ~echnique, comprising an ice-accreting surface and means mounted at said surface for transducing an ultra-sonic signal into said ice.
25 The invention also relates to a method for detection of the presence o~ ice on a surface, comprising the step~ of . - , : :' .
: . -7~, 7~7~.~
1 transmission of ~n ultra-sonic pulse into ~aid ice via trans-ducing means; propagation o~ said pulsq througil said ice to its periphery and reflecti~n of said pulse bac~ to said transducing means; and evaluating the time between transmission of said pulse and reception by said transducing means of said reflected pulse to obtain ic~ thic~ne~s, and/or ice accre~ion rate.
Description of the Drawings The preferred embodiment is illustrated in the accompanying drawings~ in which:
Fig. 1 is a partial schematic, partial blcck diagram o~ a preferred embodiment of the present invention;
Fig~ 2 is a schematic diagram illustrating the pulse echo technique of ice thickness measurement; and Fig. 3 is a graphic represen~ation of experimen~al - 15 data representing ice growth under heavy icing conditions for detection of ice thic~nes~ and gro~th rate.
~escri~tion of the Preferred Embodiment Fig 1 is a partial schematic, partial block diagram o~ the present invention~ showing ice 14 accreted on the leading edge 16 of an airfoil 18. Also provided on the leading edge 16 of airfoil 18 is an ultra-sonic transducer 20.
In a preferred embo~iment, the ultra-sonic sens~r comprise~ a broad-band, highly damped contac~ ~ransducer. This type of ~ransducer allows maximum signal penetration in attenu-ating and scattering mate~ial~ which have accreted thereon.
' ~ : ' .
'7~3~
/, _ s -- ( 1 Pre~erably, such transducer has a cent~r frequency o~ 5 MHz andan element diameter o 0.25 inches. 'rhe transducer 3hould at least ha~e a cen~er frequency o~ 1 to 20 MH~
Reerring again to FigO 1, the transducer is driven hy a pulse transmitter o~ a pulser/receiver and 3ignal proces-sor unlt 22. The pulse transmitter transmits a sig~al to the transducer 20 via conduc~or 24. This signal cau~es the tran~-ducer to emi~ a brie~ ultrasonic compression wave. The emitted ~ignal is reflec~ed at the air~ice interface o~ the ice accre-ted on the transducer and the signal thus reflected back iadetected by the transducer. Thi~ detectad reflected wave is transmitted from the transducer bacX to the pulser/receiver and ~ignal processor unit 22 by means of conductor 24~ The received signal is then processed by the signal processor with-15 in unit 22 and a signal i~ thereafter conducted to a display -~
device 26 by means of a cable 28.
As will be appreciated by those of ordinary skill in the art; the principle upon which the pulse echo feature of the invention operate~, is shown in the schematic diagram of Fig.
20 Z~ In Fig. 2, a transducer 20 i~ shown mounted flush with the su~ace o f air~oil 18. As will be seen in ~he ~igure, a pulse 31 is emi~ted by the transducer and is propagated ~hrough the ice 14 until it is reflected by the air-ice interface 30. The echo 32 is detected by the tran~ducer 20, whereupon an ele~tri-cal pulse, repre entative of the ~trength of the echo~ istransmitted to the receiver of unit 22. The ~ime delay between the emi~sion oE the pulse by the transducer and its receipt of . ' : .
1 the reflected pulse 32 is related to the thic~ness oE the ice.
This relationship is shown in Fig. 2 in the bloc~ enclosing the formula D (ice thickness) =l/2 of the quantity Cic~ (repr2sent-ing the speed of sound in ice) x Tp E (which represents the time b~tween the emission o~ the pulse and the receipt of the echo~. It will therefore be appreciated that ice thickness D
can ~e detected if the time of propagation can be detected and the speed of sound in the ice is known.
Furthermore, the inventors have determined that the speed of sound Cice in ice is insensltive to the type of ice under examination. This speed has been determined experimentally to be approximately 3.8 mm~microseconds.
Re~erring to Fig. 3, there is shown a graphic rep-resentation of e~perimen~al da~a representing ice growth under heavy icing conditions ~mploying a 4-inch diameter cylinder with the present apparatus flush mounted at the leading edge - there~f. The detectors were subjected to an icing cloud at 200 knot~ . The eloud had a med;an valume diameter of 20 microns and a li~uid water con~ent of l.2 grams per meter cubed . Three temperatures (-10F., flOF., +27~F., respectively) represent-ing three types of ice formation (rime, glaze and a second glaze, respectively) are shown. The graph of Fig. 3 compares ice thic~ness in millimeters along the ordinate axis to icing time in minutes al~ng the abscissa axis. The icing rate ~or each respective formation is represented by the slope of the respective point-plotted curve shown in the figure.
., :
' ' ' 3~
~ - 7 - ( 1 It will be appreciated that the present apparatu3 ~or measuremerl~ of ice thic!cness can be advantageou31y used in con-junctioQ with ice de-icing and anti-icing-devices to protect ~
vehicle from unwanted icing. This is particularly critical in operation of pneumatic boots, which are only effecti~e within an cer~ain limited ice thic~ness range. Therefore, knowledge of ice thickness and ice growth rate i8 critical for ef~icient operation of such de~ice.
While r~ther specific embodiments have been de~cribed herein, it will be appreciated that other and further embodi-ments within the spirit and scope of the present invention are contemplated. .~
- .
1 ~ of the Invention The present in~ention relates to ic~-prevention sy~tems for aircraft struc~ures, and more pa~ticularly, to an apparatus for measurement of ice thickness employing ultra sonic pulse echa techniques.
The problems relating to the formation of ice on aircrat s~ructures are well known. In certain cli~atic condi-tions water droplets ~ay exist at subfreezing temperatures in a liquid state. These supercooled droplet~ nucleate and ~orm ice upon contact with the aircra~t surface~. Ice the~efore tends to form on the leading edges of aircraft s~ructures. The ice can degrade aircraft performance through increasing the effec-ti~e weight o~ the aircraft and by increasing drag re~istance and reducing lift provided by~the airfolls.
lS Various ice detection devices are well known. In one known detection device, a probe is provided which extends beyond the surface to be monitored. ~owe~er, the manner of ice accretion on such prabe is different from the manner of ice accretion on the ~urface to be monitored. Hence, the accretion rate on the probe will be higher than the accretion rate on the ~ur~ace to be monitored.
In another known device, the ice thickness is mea~ured by the changing capacitance o~ a surface capacitor due to the dielectric properties of the ice which has accreted on the probe. One problem with ~hi3 latter class of devices is ~;Y~
P~
,~ tj~3 ;~
1 that in o~der to accu~htely interpret the data received from the probe, the type oE ice (rime, glaze, or mixed) must be known to the user~
It is there~ore an object of the present invention to provide an apparatus ~or measurement of ice thic~ness which can be mounted flush with the surface upon which ice accretion thic~ness is to be measured~
It is another object of the present invention provide an apparatu3 for measurement of ice thic~ness which i~
insensitive to types of ice accreted. .
It i~ yet another object of the present in~ention to .
provide an apparatus or meas~rement of ice thic~ne-~ which is .
flush with the surface upon which ice acc~etion thic~ne~ is to be measured and can also measure the rate of ice accretion.
lS It i~ a further object of the present invention to pro~ide an apparatus for measurement of-ice thic~ness employing : .
ultra-sonic pulse echo techniques to measure ice accretion .
thickne~s and al90 the rate at which :ice is accre~ed. .
-Summary of the Invention The present invention relates to an apparatus for .
: measurement o~ the thickness of accreted ice and rate of .
accretion employing an ultra-so~ic pulse e~ho ~echnique, comprising an ice-accreting surface and means mounted at said surface for transducing an ultra-sonic signal into said ice.
25 The invention also relates to a method for detection of the presence o~ ice on a surface, comprising the step~ of . - , : :' .
: . -7~, 7~7~.~
1 transmission of ~n ultra-sonic pulse into ~aid ice via trans-ducing means; propagation o~ said pulsq througil said ice to its periphery and reflecti~n of said pulse bac~ to said transducing means; and evaluating the time between transmission of said pulse and reception by said transducing means of said reflected pulse to obtain ic~ thic~ne~s, and/or ice accre~ion rate.
Description of the Drawings The preferred embodiment is illustrated in the accompanying drawings~ in which:
Fig. 1 is a partial schematic, partial blcck diagram o~ a preferred embodiment of the present invention;
Fig~ 2 is a schematic diagram illustrating the pulse echo technique of ice thickness measurement; and Fig. 3 is a graphic represen~ation of experimen~al - 15 data representing ice growth under heavy icing conditions for detection of ice thic~nes~ and gro~th rate.
~escri~tion of the Preferred Embodiment Fig 1 is a partial schematic, partial block diagram o~ the present invention~ showing ice 14 accreted on the leading edge 16 of an airfoil 18. Also provided on the leading edge 16 of airfoil 18 is an ultra-sonic transducer 20.
In a preferred embo~iment, the ultra-sonic sens~r comprise~ a broad-band, highly damped contac~ ~ransducer. This type of ~ransducer allows maximum signal penetration in attenu-ating and scattering mate~ial~ which have accreted thereon.
' ~ : ' .
'7~3~
/, _ s -- ( 1 Pre~erably, such transducer has a cent~r frequency o~ 5 MHz andan element diameter o 0.25 inches. 'rhe transducer 3hould at least ha~e a cen~er frequency o~ 1 to 20 MH~
Reerring again to FigO 1, the transducer is driven hy a pulse transmitter o~ a pulser/receiver and 3ignal proces-sor unlt 22. The pulse transmitter transmits a sig~al to the transducer 20 via conduc~or 24. This signal cau~es the tran~-ducer to emi~ a brie~ ultrasonic compression wave. The emitted ~ignal is reflec~ed at the air~ice interface o~ the ice accre-ted on the transducer and the signal thus reflected back iadetected by the transducer. Thi~ detectad reflected wave is transmitted from the transducer bacX to the pulser/receiver and ~ignal processor unit 22 by means of conductor 24~ The received signal is then processed by the signal processor with-15 in unit 22 and a signal i~ thereafter conducted to a display -~
device 26 by means of a cable 28.
As will be appreciated by those of ordinary skill in the art; the principle upon which the pulse echo feature of the invention operate~, is shown in the schematic diagram of Fig.
20 Z~ In Fig. 2, a transducer 20 i~ shown mounted flush with the su~ace o f air~oil 18. As will be seen in ~he ~igure, a pulse 31 is emi~ted by the transducer and is propagated ~hrough the ice 14 until it is reflected by the air-ice interface 30. The echo 32 is detected by the tran~ducer 20, whereupon an ele~tri-cal pulse, repre entative of the ~trength of the echo~ istransmitted to the receiver of unit 22. The ~ime delay between the emi~sion oE the pulse by the transducer and its receipt of . ' : .
1 the reflected pulse 32 is related to the thic~ness oE the ice.
This relationship is shown in Fig. 2 in the bloc~ enclosing the formula D (ice thickness) =l/2 of the quantity Cic~ (repr2sent-ing the speed of sound in ice) x Tp E (which represents the time b~tween the emission o~ the pulse and the receipt of the echo~. It will therefore be appreciated that ice thickness D
can ~e detected if the time of propagation can be detected and the speed of sound in the ice is known.
Furthermore, the inventors have determined that the speed of sound Cice in ice is insensltive to the type of ice under examination. This speed has been determined experimentally to be approximately 3.8 mm~microseconds.
Re~erring to Fig. 3, there is shown a graphic rep-resentation of e~perimen~al da~a representing ice growth under heavy icing conditions ~mploying a 4-inch diameter cylinder with the present apparatus flush mounted at the leading edge - there~f. The detectors were subjected to an icing cloud at 200 knot~ . The eloud had a med;an valume diameter of 20 microns and a li~uid water con~ent of l.2 grams per meter cubed . Three temperatures (-10F., flOF., +27~F., respectively) represent-ing three types of ice formation (rime, glaze and a second glaze, respectively) are shown. The graph of Fig. 3 compares ice thic~ness in millimeters along the ordinate axis to icing time in minutes al~ng the abscissa axis. The icing rate ~or each respective formation is represented by the slope of the respective point-plotted curve shown in the figure.
., :
' ' ' 3~
~ - 7 - ( 1 It will be appreciated that the present apparatu3 ~or measuremerl~ of ice thic!cness can be advantageou31y used in con-junctioQ with ice de-icing and anti-icing-devices to protect ~
vehicle from unwanted icing. This is particularly critical in operation of pneumatic boots, which are only effecti~e within an cer~ain limited ice thic~ness range. Therefore, knowledge of ice thickness and ice growth rate i8 critical for ef~icient operation of such de~ice.
While r~ther specific embodiments have been de~cribed herein, it will be appreciated that other and further embodi-ments within the spirit and scope of the present invention are contemplated. .~
- .
Claims (17)
1. An apparatus for measurement, of the thickness of ice on an ice-accreting surface employing an ultra-sonic pulse echo technique, comprising:
an ice-accreting surface;
transducer means mounted at said surface for transmitting an ultra-sonic signal into said ice and for receiving a reflec-ted signal; and means for evaluating the time delay between transmission and reception of the ultra-sonic signal, the time delay indica-tive of the thickness of the ice.
an ice-accreting surface;
transducer means mounted at said surface for transmitting an ultra-sonic signal into said ice and for receiving a reflec-ted signal; and means for evaluating the time delay between transmission and reception of the ultra-sonic signal, the time delay indica-tive of the thickness of the ice.
2. The apparatus of claim 1, wherein said transducer means comprises at least one transducer mounted flush at said surface.
3. The apparatus of claim 1, wherein said transducer is mounted behind said surface.
4. The apparatus of claim 1, wherein said transducer is mounted on said surface.
5. The apparatus of claim 1, further comprising a pulse transmitter and receiver operatively coupled to said transducing means.
6. The apparatus of claim 1, further comprising a signal processor operatively coupled to said transducing means.
7. The apparatus of claim 1, further comprising a display operatively coupled to said transducing means.
8. The apparatus of claim 7, wherein said display comprises means for indicating ice thickness and accretion rate.
9. The apparatus of claim 7, wherein said display comprises an ice warning indicator.
10. The apparatus of claim 13 wherein said transducing means comprises a broadband, highly damped contact transducer.
11. The apparatus of claim 10, wherein said transducing means has a center frequency range of 1-20 MHz.
12. The apparatus of claim 11, wherein said center frequency is approximately 5 MHz.
13. The apparatus of claim 1, wherein said transducing means comprises a piezo electric element.
14. The apparatus of claim 13, wherein said element has a diameter of approximately 0.25 inches.
15. A method for detection of the presence of ice on a surface, comprising the steps of:
(a) transmission of an ultra-sonic pulse into said ice via transducing means mounted at said surface;
(b) propagation of said pulse through said ice to its periphery and reflection of said pulse back to said transducing means; and (c) evaluating the time between transmission of said pulse and reception by said transducing means of said reflec-ted pulse to obtain ice thickness.
(a) transmission of an ultra-sonic pulse into said ice via transducing means mounted at said surface;
(b) propagation of said pulse through said ice to its periphery and reflection of said pulse back to said transducing means; and (c) evaluating the time between transmission of said pulse and reception by said transducing means of said reflec-ted pulse to obtain ice thickness.
16. A method for detection of the presence of ice on a surface, comprising the steps of:
(a) transmission of an ultra-sonic pulse into said ice via transducing means mounted at said surface;
(b) propagation of said pulse through said ice to its periphery and reflection of said pulse back to said transducing means; and (c) evaluating the time between transmission of said pulse and reception by said transducing means of said reflected pulse to obtain ice accretion rate.
(a) transmission of an ultra-sonic pulse into said ice via transducing means mounted at said surface;
(b) propagation of said pulse through said ice to its periphery and reflection of said pulse back to said transducing means; and (c) evaluating the time between transmission of said pulse and reception by said transducing means of said reflected pulse to obtain ice accretion rate.
17. A method for controlling ice protection devices comprising the steps of determining the presence and thickness of ice on a surface protected by said protection devices, according to claim 16, by means of ultra-sonic pulse echo de-tection, and directing said devices to protectively operate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000511245A CA1272795A (en) | 1986-06-10 | 1986-06-10 | Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000511245A CA1272795A (en) | 1986-06-10 | 1986-06-10 | Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1272795A true CA1272795A (en) | 1990-08-14 |
Family
ID=4133320
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000511245A Expired - Fee Related CA1272795A (en) | 1986-06-10 | 1986-06-10 | Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1272795A (en) |
-
1986
- 1986-06-10 CA CA000511245A patent/CA1272795A/en not_active Expired - Fee Related
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