Ultrasonic Air Data Pole Layout for Boundary Layer Signal Accuracy
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Solution Overview
Problem
Existing air data systems face challenges with signal attenuation and complex calibration due to directional transmitters and velocity gradients, requiring complex horn structures and high signal strength, which affect measurement accuracy and resolution.
Innovation Solution
An ultrasonic air data system with a transmitter facing backward and extending outside the boundary layer, using a pole with a heater to prevent icing, and a controller to optimize directivity and signal strength, allowing for improved signal propagation and reduced susceptibility to icing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional directional transmitters with horn structures are used, then signal propagation is improved, but device complexity increases
Solution Approach 1:
The invention extracts the transmitter from the boundary layer environment by mounting it on a pole extending above the aircraft surface. This removes the transmitter from the harmful velocity gradients and turbulence within the boundary layer, improving signal propagation without requiring complex horn structures to compensate for environmental degradation.
Solution Approach 2:
The transmitter is positioned in a different spatial dimension (above the boundary layer) rather than within it. By extending the pole vertically above the aircraft surface, the system accesses a region with more favorable flow conditions, eliminating the need for complex directional control structures.
2Ease of manufacture
If transmitters are mounted within the boundary layer, then installation is simplified, but measurement precision deteriorates due to velocity gradients and signal attenuation
Solution Approach 1:
The pole acts as an intermediary structure that connects the aircraft surface to the transmitter. It extends the transmitter into a region above the boundary layer where velocity gradients are minimal, providing a stable acoustic environment for precise measurements while maintaining a simple mounting structure.
3Reliability
If high signal strength is used to overcome attenuation, then measurement reliability is improved, but power consumption increases
Solution Approach 1:
The invention converts the harmful boundary layer environment into a benefit by positioning the transmitter above it. The pole-mounted configuration uses the free stream airflow above the boundary layer as a natural acoustic waveguide, reducing signal attenuation and enabling reliable detection with lower power consumption.
4Measurement precision
If complex calibration procedures are used to account for boundary layer effects, then measurement accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
By extracting the receivers from the boundary layer environment and positioning them above it on the pole structure, the system eliminates the need for complex calibration procedures to compensate for boundary layer velocity gradients. The measurement environment is naturally optimized, simplifying operation while maintaining high accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances measurement accuracy and resolution by providing a direct path to receivers, reducing signal attenuation and complexity, while allowing for a lower power transmitter and easier calibration.
Implementation Method 1
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
Implementation Method 2
The pole can include a heater configured to prevent icing (e.g., on the pole and/or transmitter)
Implementation Method 3
velocity and temperature gradients can attenuate the signal
Data Source
Figure 1
AI summary
An ultrasonic air data system (100) can include a pole (103) having a length (103) longer than a boundary layer thickness (105) of a boundary layer flow (107) 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. The system can include 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. The system can include one or more receivers (115) disposed downstream of the pole as defined by the boundary layer flow and configured to receive the transmitter signal.