Beam Drift Mitigation and Wide-Range Measurement in a Miniaturized Ultrasonic Gas Flowmeter

Area of Science:

• Engineering
• Acoustics
• Instrumentation

Background:

• Acoustic beam drift in ultrasonic gas flowmeters (USFMs) degrades signal-to-noise ratio (SNR) and limits measurement range.
• Miniaturization of USFMs is crucial for broader applications but faces challenges with maintaining accuracy.

Purpose of the Study:

• To develop a miniaturized transit-time USFM that mitigates acoustic beam drift.
• To enhance acoustic transmission gain and directivity for improved flow measurement.

Main Methods:

• Integration of a single piezoelectric micromachined ultrasonic transducer (PMUT) with a non-axisymmetric conical cavity.
• Optimization of the conical cavity angle combination to (50°, 70°).
• Experimental validation of acoustic performance and flow measurement accuracy.

Main Results:

• Achieved a 7.4 dB transmission gain and a half-power beamwidth (HPBW) of 29.1°.
• Demonstrated minimal sound pressure attenuation (0.72 dB at 18.74 m/s).
• Exhibited indication errors of ±2% (<1 m³/h) and ±1.5% (≥1 m³/h) with repeatability <0.5% within a 0.06-12 m³/h range.

Conclusions:

• The developed USFM meets Class 1.5 accuracy standards (CJ/T 477-2015).
• The non-axisymmetric conical cavity design effectively reduces beam steering and broadens acoustic coverage.
• Offers an innovative solution for wide-range, miniaturized gas flow measurement.