Ultrasonic Air Data System Acoustic Source Signal Shaping
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Solution Overview
Problem
Existing acoustic sources for air data systems have limited amplitude and directivity, leading to quick attenuation of high frequencies in air and high background noise issues, particularly at high aircraft speeds, making them inadequate for precise measurements.
Innovation Solution
The implementation of a SASAR acoustic source with a generator and gate, combined with an acoustic signal shaping feature like a waveguide or horn, to produce high-amplitude directional acoustic signals that are reshaped for optimal propagation and reception by acoustic receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing acoustic sources are used, then the system structure is simple, but the amplitude and directivity are limited causing quick attenuation of high frequencies
Solution Approach 1:
The patent employs a composite acoustic source structure combining a resonating stack with metamaterial gates. The metamaterial component introduces unique acoustic properties that enhance directivity and amplitude while the resonating stack provides the acoustic generation mechanism. This composite approach resolves the contradiction by achieving superior signal quality through material composition rather than simple geometric design.
Solution Approach 2:
The patent introduces an acoustic horn as an intermediary component between the acoustic source and the external environment. The horn acts as a mediator that transforms the acoustic output, improving directivity and reducing attenuation of high frequencies. This intermediary element enables the system to achieve better signal quality without fundamentally redesigning the core acoustic source.
2Measurement precision
If high frequency acoustic signals are used, then measurement precision is improved, but the signals attenuate quickly in air
Solution Approach 1:
The patent utilizes mechanical vibration principles through the resonating stack structure, which is designed to vibrate at specific resonant frequencies. This mechanical vibration approach generates high-frequency acoustic signals with sufficient amplitude to overcome atmospheric attenuation. The resonant vibration mechanism efficiently converts input energy into acoustic energy at the desired high frequencies, maintaining measurement precision while compensating for energy loss.
Solution Approach 2:
The patent employs periodic acoustic signaling through the resonating stack, which naturally produces periodic vibrations at its resonant frequency. This periodic action creates sustained high-frequency signals that maintain their energy longer in the atmosphere compared to transient signals. The periodic nature of the resonant vibration ensures consistent signal quality for precise velocity measurements while mitigating attenuation effects.
3Measurement precision
If high frequency acoustic signals are used, then measurement precision is improved, but background noise increases at high aircraft speeds
Solution Approach 1:
The patent applies local quality enhancement through the metamaterial gates, which are strategically positioned to control acoustic wave propagation in specific directions. The metamaterial structure creates localized acoustic properties that enhance the main signal while suppressing noise from other directions. This spatially selective acoustic manipulation improves signal-to-noise ratio by enhancing the desired high-frequency signal characteristics while attenuating background noise, particularly important at high aircraft speeds where noise levels increase.
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
This solution enhances the signal-to-noise ratio and provides more reliable air data measurements by emitting directional, high-amplitude ultrasonic signals that are effectively received and analyzed for determining flow characteristics, overcoming the limitations of existing sources.
Implementation Method 1
Certain SASAR (Sound Amplification through the Synchronous Accumulation of Radiation) acoustic sources create high amplitude acoustic vibrations using a combination of a resonating stack and a metamaterial gate
Implementation Method 2
Ultrasonic air data systems can utilize an acoustic signal to measure freestream velocity, flow angle, and speed of sound, for example, using the transmission time between an acoustic source(s) and acoustic receivers
Implementation Method 3
create high amplitude acoustic vibrations using a combination of a resonating stack and a metamaterial gate
Data Source
Figure 1
AI summary
An ultrasonic air data system (UADS) can include a body (101) configured to mount to an aircraft, an acoustic signal shaping feature (103) associated with the body (101), and an acoustic source (105) operatively connected to the acoustic signal shaping feature (103), the acoustic source (105) configured to emit a directional acoustic signal. The acoustic signal shaping feature (103) can be configured to reshape the directional acoustic signal from the acoustic source (105) into an at least partially reshaped signal. The system can include one or more acoustic receivers (107) disposed on or at least partially within the body (101) for receiving the reshaped signal.