Non-Intrusive Sonic Anemometry for High Subsonic Jet Velocity
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Solution Overview
Problem
Existing acoustic velocity measurement techniques, such as Acoustic Doppler Velocimetry and Sonic Anemometry, face challenges in high subsonic Mach number jets due to the need for entrained particles, low signal-to-noise ratio, and limitations in measuring velocities above 100 m/s, especially in noisy environments.
Innovation Solution
A non-intrusive sonic anemometry method using a single sound source and two microphones positioned on one side of a flow field, emitting an acoustic wave and measuring time delays to determine flow velocity without upstream propagation, thereby improving signal-to-noise ratio and extending measurement capabilities to high subsonic Mach numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Acoustic Doppler Velocimetry is used to measure flow velocity, then velocity measurement can be performed, but the technique requires entrained particles which must be introduced into the flow stream, making it impractical for in situ applications
Solution Approach 1:
The invention extracts and eliminates the requirement for entrained particles from the measurement system. By using acoustic scattering from turbulent eddies and flow structures inherently present in high-speed jets rather than requiring externally introduced particles, the method makes velocity measurement practical for in situ applications while maintaining measurement capability
Solution Approach 2:
The measurement system utilizes self-generated acoustic scattering sources within the flow field itself. Turbulent eddies, shear layers, and flow structures naturally present in high-speed jets serve as the scattering mechanisms, eliminating the need for external particle introduction and enabling autonomous in situ measurement
2Measurement precision
If Acoustic Doppler Velocimetry is used in high noise environments, then velocity measurement can be attempted, but the signal-to-noise ratio becomes too low for reliable measurement
Solution Approach 1:
The invention changes the operating parameters of the acoustic measurement system by using higher frequencies (40-200 kHz) and optimizing the acoustic path geometry. These parameter changes increase the strength of acoustic scattering from flow structures and improve signal detection capability, enabling reliable velocity measurement in high noise environments where traditional ADV fails
3Measurement precision
If traditional Sonic Anemometry is used for velocity measurement, then time of flight measurements can be made, but the technique has only been proven for low Mach numbers (less than 0.3) with velocity ranges limited to ±30 m/s or up to 60 m/s
Solution Approach 1:
The invention adapts the sonic anemometry technique by making the measurement system dynamic and adjustable for high-speed flows. By using multiple acoustic paths at different angles and frequencies, and by implementing real-time signal processing algorithms that account for Mach number effects, the system extends measurement capability from low Mach numbers (0.3) to high subsonic regimes while maintaining accuracy
Solution Approach 2:
The measurement system is designed with multi-functionality to handle both low and high Mach number regimes. By incorporating multiple acoustic transducers, adjustable frequency ranges (40-200 kHz), and versatile signal processing capabilities, the system can adapt to different flow conditions and extend the universal applicability of sonic anemometry beyond its traditional low-speed limitations
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 method enables accurate, non-invasive measurement of flow velocity in high subsonic Mach number jets with improved signal-to-noise ratio, eliminating the need for entrained particles and extending measurement ranges, providing reliable velocity data in noisy environments.
Implementation Method 1
measuring a time delay between transmission of the acoustic signal and receipt of the acoustic signal by the acoustic receivers
Implementation Method 2
A non-intrusive sonic anemometry method using a single sound source and two microphones positioned on one side of a flow field
Data Source
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AI summary
A system and method of non-intrusive thrust measurement of a gas turbine engine. A transmitter is disposed at a boundary of fluid flow and at least one receiver is adapted to receive transmissions from the transmitter. A processor is coupled to the receivers to determine a parameter from a characteristic of the transmission at the receiver suite and adapted to determine a thrust parameter from the parameter. Flow velocity can be measured using an acoustic emitter and two acoustic receivers arranged downstream of the emitter.