ACOUSTIC AIR DATA SYSTEMS

Description

BACKGROUND 1. Field

[0001] This disclosure relates to air data system, more specifically to acoustic air data systems (e.g., ultrasonic airspeed, temperature, and / or direction systems).2. Description of Related Art

[0002] Aircraft air data systems can utilize ultrasonic sensing for generating airspeed, temperature (e.g., through the speed of sound), and flow direction (e.g., AOA or AOS depending on installation). Performance of an ultrasonic air data system that utilizes an ultrasonic transmitter and an array of receivers and a time-of-flight measurement is directly dependent on a number of factors. The frequency of the sound wave, the distance the sound wave has to travel, the speed of sound of the medium in which it's traveling through, the attenuation of the sound due to a number of factors, and the relative wind speed and direction. Measurement principles such as the sampling rate and the accuracy of any estimation algorithms and calibration are also part of a total performance of this system.

[0003] Existing transmitters are directional and can require a horn structure in order for the transmitter signal to propagate to the receivers. Also, velocity and temperature gradients can attenuate the signal, so existing flush mounting may require complex calibration and a high signal strength.

[0004] Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved acoustic air data systems. The present disclosure provides a solution for this need.

[0005] FR 2 948 458 A1 discloses an air data system for measuring the relative airspeed of an aircraft. An ultrasonic emitter is located on a mast upstream and an ultrasonic receiver is located downstream on the aircraft tail.

[0006] FR2 974 908 A1 and FR 3 027 398 A1 disclose air data systems comprising an ultrasonic airspeed sensing system with upstream transmitters and downstream receivers located on the aircraft tail. The configuration allows the acoustic wave path to lie outside the boundary layer.

[0007] JP S54 86199 A discloses an air data system comprising an airspeed sensor located outside the boundary layer, comprising an ultrasonic transmitter and an ultrasonic receiver.

[0008] EP 1 494 032 A1 discloses a static pressure sensing probe with deicing systems such as a vibration or impact deicing system. Ultrasonic generators that send vibrations through the probe can also be used.SUMMARY

[0009] An ultrasonic air data system as defined in claim 1 is provided. The system can include a controller configured to receive one or more signals from the one or more receivers and / or to operate the transmitter (e.g., as a function of one or more received signals). The controller can include any suitable hardware and / or software module(s) as appreciated by those having ordinary skill in the art in view of this disclosure.

[0010] The transmitter can be configured to face backward along the aircraft for providing at least one of reduced susceptibility to icing, optimized directivity towards the one or more receivers, or extension of the signal just outside of the boundary layer.

[0011] In certain embodiments, the transmitter can be configured to vibrate radially with compression of the pole. The transmitter can be configured to vibrate axially or both axially and radially. Any suitable vibration is contemplated herein.

[0012] In certain embodiments, the system can include one or more receivers upstream of the pole. Any other suitable location is contemplated herein.

[0013] The one or more receivers can include a plurality of receivers. The plurality of receivers can be installed on a single plate (e.g., flush mounted to the aircraft), or any suitable number can be mounted individually to the aircraft. Any suitable pattern for a plurality of receivers as appreciated by those having ordinary skill in the art is contemplated herein.

[0014] In certain embodiments, the pole can include a heater configured to prevent icing (e.g., on the pole and / or transmitter). Any suitable heater (e.g., resistive) is contemplated herein.

[0015] In certain embodiments, the pole can extend outwardly perpendicular to the aircraft surface. Any other suitable angle of the pole relative to the aircraft surface is contemplated herein.

[0016] In accordance with at least one aspect of this disclosure, a method for determining air data as defined in claim 8 is provided.

[0017] These and other features of the embodiments of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, embodiments thereof will be described in detail herein below with reference to figure 1, wherein: Fig. 1 is a schematic diagram of an embodiment of a system in accordance with this disclosure.DETAILED DESCRIPTION

[0019] 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, an illustrative view of an embodiment of a system in accordance with the disclosure is shown in Fig. 1 and is designated generally by reference character 100. Certain embodiments described herein can be used to improve acoustic air data measurements, for example.

[0020] An ultrasonic air data system 100 includes a pole 101 having a length 103 longer than a boundary layer thickness 105 of a boundary layer flow 107 such that at least a distal end 101a of the pole 101 is configured to extend outwardly from an aircraft surface 109 to be at least partially outside of the boundary layer flow 107.

[0021] The system 100 includes a transmitter 111 disposed on or in the pole 101 at or near the distal end 101a of the pole 101 such that the transmitter 111 is located at least partially (e.g., entirely) outside of the boundary layer flow 107 when in use (e.g., at all flight conditions of an aircraft). The transmitter 111 is configured to output an acoustic transmitter signal 113 (e.g., an ultrasonic signal). The transmitter signal 113 can be generated by any suitable acoustic signal generator (not shown) as appreciated by those having ordinary skill in the art (e.g., an ultrasonic signal generator). Any suitable signal frequency is contemplated herein.

[0022] The system 100 includes one or more receivers 115 disposed downstream of the pole 101 as defined by the boundary layer flow and configured to receive the transmitter signal 113. Any suitable number of receivers 115 is contemplated herein.

[0023] The system 100 can include a controller 117 configured to receive one or more signals from the one or more receivers 115 and / or to operate the transmitter 111 (e.g., as a function of one or more received signals). The controller 117 can be configured to control a frequency and / or amplitude of the transmitter signal 113 output by the transmitter 111 The controller 117 can include any suitable hardware and / or software module(s) as appreciated by those having ordinary skill in the art in view of this disclosure.

[0024] According to the invention, the length 103 of the pole 101 is between about 2,5 cm (1 inch) and about 12,7 cm (5 inches).

[0025] The transmitter 111 can be configured to face backward (e.g., in the downstream direction) along the aircraft for providing at least one of reduced susceptibility to icing, optimized directivity towards the one or more receivers 115, or extending the signal 113 just outside of the boundary layer 107. An axial distance 119 between the pole 101 and the one or more receivers 115 can be defined based on at least one of a frequency of the transmitter signal 113, a transmitter efficiency, and a maximum sound pressure level output, for example. Any other suitable factors for setting axial distance 119 are contemplated herein.

[0026] In certain embodiments, the transmitter 111 can be configured to vibrate only radially (inward and outward) with compression of the pole. The transmitter 111 can be configured to vibrate axially, or both axially and radially, for example. Any suitable vibration is contemplated herein.

[0027] In certain embodiments, the system 100 can include one or more receivers 115 upstream of the pole 101. Any other suitable location is contemplated herein. As shown, the one or more receivers 115 can include a plurality of receivers 115. The plurality of receivers 115 can be installed on a single plate 121 (e.g., flush mounted to the aircraft), or any suitable number can be mounted individually to the aircraft. Any suitable pattern for a plurality of receivers 115 as appreciated by those having ordinary skill in the art is contemplated herein.

[0028] In certain embodiments, the pole 101 can include a heater 123 configured to prevent icing (e.g., on the pole 101 and / or transmitter 111). Any suitable heater (e.g., resistive) is contemplated herein. In certain embodiments, the heater 123 can be controlled by the controller 117 as a function of any suitable variable, such as temperature or ice formation detection.

[0029] In certain embodiments, as shown the pole 101 can extend outwardly perpendicular to the aircraft surface 109. Any other suitable angle (e.g., 45 degrees) of the pole 101 relative to the aircraft surface 109 is contemplated herein. The angle may be a function of axial distance of the one or more receivers 115 (e.g., and / or plate 121) to the pole 101 and / or pole length 103. In certain embodiments, the pole 101 could be include a swept-back shape, (e.g., straight or curved).

[0030] A transmitter assembly for an acoustic air data system includes a pole (e.g., 101) having a length (e.g., 103) longer than a maximum boundary layer thickness of a boundary layer flow on an aircraft of a predetermined cruise speed such that at least a distal end of the pole is configured to extend outwardly from an aircraft surface to be at least partially outside of the boundary layer flow, and a transmitter (e.g., 111) disposed on or in the pole at or near a distal end of the pole such that the transmitter is located at least partially outside of the boundary layer flow when in use, wherein the transmitter is configured to output a transmitter signal. The pole and transmitter can include any suitable embodiment as disclosed herein (e.g., as described above).

[0031] In accordance with at least one aspect of this disclosure, a method for determining air data is defined in claim 8, and includes transmitting a transmitter signal outside of a boundary layer flow in a flow field into the boundary layer flow to be received by one or more receivers within the boundary layer flow. The method can include receiving a received signal at the one or more receivers. The method can include determining at least one of airspeed, temperature, and / or direction of the flow field based on at least one quality of the received signal compared to the transmitted signal. The at least one quality of the received signal includes time-of-flight between the transmitter and the one or more receivers.

[0032] The transmitter is above a boundary layer so that more accurate measurements can be made of free stream conditions. Embodiments can include a source that has a more direct path to the receivers, and signal shaping (e.g., with hom) can be reduced or eliminated as a result. Embodiments can utilize a lower power transmitter than that required in existing systems.

[0033] Certain embodiments can account for icing by having the transmitter rear facing so icing would only build up on a non-functional side of the pole, for example. The invention has a high enough amplitude sound vibration to shake off icing. Certain embodiments can have a heater to heat the transmitter.

[0034] Embodiments allow the distance between the transmitter and receivers to be increased, which can improve resolution of measurements. Existing flush mounted systems cannot as spread apart due to size restrictions as well as signal attenuation issues.

[0035] Certain embodiments of a controller (e.g., 117 disclosed above) can include any suitable processing hardware and / or software modules for resolving the airspeed, direction, and speed of sound components through signals received by the one or more receivers (e.g., an array of downstream receivers). In certain embodiments, the transmitter and receivers can be electrically connected to a single processing and controller unit (e.g., controller 117).

[0036] Certain embodiments allow the majority of the atmospheric measurement to be taken in a region of airflow that is easily calibrated as appreciated by those having ordinary skill in the art in view of this disclosure. The optimal distance to the receiver array could be defined based on the frequency of the generated source, transmitter efficiency, and max sound pressure level output, in addition to the required performance of the airspeed measurement.

[0037] Certain embodiments provide an advantage to a flush installation in that omni-directivity of a transmitter is not required, which at higher frequencies is more difficult and requires a horn or similar features. Embodiments can also reduce the effect of the velocity gradient in the boundary layer which aids in improving measurement accuracy and resolution.

[0038] The embodiments of the present disclosure, as described above and shown in the drawings, provide for improvement in the art to which they pertain. While the subject disclosure includes reference to certain embodiments, those skilled in the art will readily appreciate that changes and / or modifications may be made thereto without departing from the scope of the invention, which is defined by the appended claims.

Claims

1. An ultrasonic air data system (100), comprising: a transmitter assembly for an acoustic air data system, comprising: an aircraft; a pole (101) having a length longer than a maximum boundary layer thickness (105) of a boundary layer flow (107) on the aircraft of a predetermined cruise speed such that at least a distal end (101a) of the pole is configured to extend outwardly from the aircraft surface (109) to be outside of the boundary layer flow; and a transmitter (111) disposed on or in the pole at or near the distal end of the pole such that the transmitter is located at least partially outside of the boundary layer flow when in use, wherein the transmitter is configured to output a transmitter signal (113); the ultrasonic air data system further comprising one or more receivers (115) disposed downstream of the pole as defined by the boundary layer flow and configured to receive the transmitter signal; characterized in that the length of the pole is between 2,5cm (1 inch) and about 12,7 cm (5 inches); and in that the transmitter is configured to vibrate with compression of the pole with a high enough amplitude to shake off icing.

2. The system of claim 1, further comprising a controller configured to receive one or more signals from the one or more receivers and / or to operate the transmitter.

3. The system of claim 1 or 2, wherein the transmitter is configured to face backward along the aircraft for providing at least one of reduced susceptibility to icing, optimized directivity towards the one or more receivers, or extension of the signal just outside of the boundary layer.

4. The system of any of claims 1 to 3, further comprising one or more receivers upstream of the pole.

5. The system of any of claims 1 to 4, wherein the one or more receivers include a plurality of receivers, and preferably wherein the plurality of receivers are installed on a single plate.

6. The system of any of claims 1 to 5, wherein the pole includes a heater configured to prevent icing.

7. The system of any of claims 1 to 6, wherein the pole extends outwardly perpendicular to the aircraft surface.

8. A method for determining air data, comprising: transmitting a transmitter signal using the ultrasonic air data system of claim 1 outside of the boundary layer flow in a flow field into the boundary layer flow to be received by the one or more receivers within the boundary layer flow.

9. The method of claim 8, further comprising receiving a received signal at the one or more receivers, and preferably further comprising determining at least one of airspeed, temperature, and / or direction of the flow field based on at least one quality of the received signal compared to the transmitted signal, and more preferably wherein the at least one quality of the received signal includes time-of-flight between the transmitter and the one or more receivers.

10. The method of claim 8 or 9, further comprising: defining a distance (119) along the axis of the aircraft between the pole and the one or more receivers based on at least one of a frequency of the transmitter signal, a transmitter efficiency, and a maximum sound pressure level output.